FACing THE FuTuRE niDCR REsEARCHERs oFFER THEiR vision oF THE by yaofenjin

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									                   CHAPTER 1                          be in a much better position in the years ahead       “One hundred years ago, claiming that an
    FACing THE FuTuRE: niDCR                          to dispense molecular medicine and repair more        ectodermal derivative such as the neural crest
                                                      naturally a congenital problem or heal a diseased     was in any way involved with the formation of
                                                      tissue. They also will be more attuned to the         skeletal structures was the embryological and
        THE 21sT CEnTuRy                              early molecular warning signs of developing           evolutionary equivalent of nailing an additional
                  (3 CE HouRs)                        disease. This will allow earlier and more accurate    thesis to the cathedral door,” wrote Langille
Learning objectives                                   diagnoses to correct problems before they             and Hall in the early 1990s, referring to Martin
!   Review scientific research on craniofacial        become advanced, chronic and destructive.             Luther’s famous Protestant rebellion. “That
    development.                                                                                            skeletal structures were mesodermal in origin
    Identify National Institute of Dental and         As part of this glimpse forward, the NIDCR
!                                                                                                           was dogma, known and accepted by all; an
    Craniofacial Research (NIDCR) ideas               highlights related areas of dental and oral
                                                                                                            ectodermal origin was heresy.”
    on the systematic model of craniofacial           research that hold tremendous promise. These
    development.                                      include studies of head and neck cancer, the          Today, the controversy has ebbed. Scientists
!   Explain how neural crest cells assist in          development of saliva as a diagnostic fluid, more     have solidly established that these short-lived
    the development of the formation of the           effective control of orofacial pain, and ongoing      precursor cells come in four distinct types, all
    craniofacial plate.                               hands-on efforts in communities across the nation     of which are programmed to migrate throughout
!   Identify the development of replacement           to help translate the fruits of our science into      the body and seed new tissue. Among them are
    tissues for damaged teeth.                        improved health care.                                 the cranial neural crest cells that, as mentioned
    Discover the future possibilities to regenerate                                                         above, help to generate most of the distinctive
!                                                     To tell these stories involves a new language of
    damaged gingival, ligament and bone.                                                                    skeletal structures of the head and face. Although
                                                      discovery. These include more familiar terms
                                                                                                            the mystery of neural crest cells historically
introduction                                          such as genomics, or the study of genes across
                                                                                                            has attracted anatomists and evolutionary
This course presents researchers and their views      species, and proteomics, the companion term for
                                                                                                            biologists, the last few decades have brought
on related studies of dental and oral research        proteins. It also includes more recently minted
                                                                                                            more molecular and cell biologists to the field.
that promise giant steps in the future. The           biological pursuits such as the interactome, the
                                                                                                            The prospect of increased collaboration among
material consists of questions and answers from       complete set of possible protein interactions
                                                                                                            the scientific disciplines coupled with the rapid
grantees of the National Institute of Dental and      within a cell, and the microbiome, the complete
                                                                                                            progress in research technology promises to
Craniofacial Research. These scientists use the       set of microorganisms that inhabit distinct parts
                                                                                                            herald a new era of discovery in craniofacial
latest molecular and genetic tools to conduct         of the body, such as the mouth, and greatly
research on the full spectrum of topics related to    influence our health and susceptibility to disease
craniofacial, oral and dental health and disease.     over time.                                            To take a closer look at neural crest cells,
In this course, you will meet each of these                                                                 craniofacial development and the research job
                                                      These and other terms represent the need
researchers and review some of the challenges                                                               ahead, two NIDCR grantees offer their thoughts.
                                                      for conceptual distinctions in science. While
they are facing.                                                                                            We start with Dr. Marianne Bronner-Fraser, a
                                                      organizationally helpful, they are in many ways
                                                                                                            biologist at the California Institute of Technology
The six researchers and grantees are:                 artificial. All human biology is one, from head
                                                                                                            in Pasadena, and Dr. Paul Trainor, a scientist at
 Dr. Marianne Bronner-Fraser, a biologist            to toe. As NIDCR-supported research unfolds
                                                                                                            the Stowers Institute for Medical Research in
   at the California Institute of Technology in       in the years ahead, its lessons will have broad
                                                                                                            Kansas City, Missouri.
   Pasadena, California.                              applications throughout science and, more
 Dr. Paul Trainor, a scientist at the Stowers        importantly, in hospitals, clinics and dental         Marianne Bronner-Fraser
   Institute for Medical Research in Kansas           offices across the land.
   City, Missouri.                                    One final note: Although the scientists
 Dr. Richard Maas, a scientist at Brigham            highlighted here are all outstanding, they
   and Women’s Hospital and Harvard Medical           represent just a cross section of a much larger
   School in Boston, Massachusetts.                   community of NIDCR researchers and grantees
 Dr. Malcolm Snead, a scientist at the               who are making important contributions to their
   University of Southern California, Los             fields and the nation’s public health.
   Angeles, California.
 Dr. William Giannobile, a researcher at             Part I: Neural crest cells: The first
   the University of Michigan in Ann Arbor,           mystery of craniofacial development
   Michigan.                                          In 1868, the Swiss embryologist Wilhelm His
 Dr. Pamela Robey, a National Institute of           spotted a thin band of previously undetected
   Dental and Craniofacial Research scientist in      cells bunched between fetal ectoderm and the
   Bethesda, Maryland.                                inchoate neural tube of a developing chick. Dr.
                                                      His called his find the Zwischenstrang, or “the
On its 60th anniversary, the NIDCR looks              intermediate cord.” By the end of the century, the
to the future and the likelihood of a more                                                                           Dr. Marianne Bronne-Fraser
                                                      German word Zwischenstrang had been scrapped                 California Institute of Technology
systematic model of craniofacial development.         for the more descriptive English term “neural
The pages that follow offer the perspectives                                                                             Pasadena, California
                                                      crest cells,” denoting the geographic crest of
of several NIDCR researchers and grantees on          the neural tube as their site of origin. The cells    In studying craniofacial development, why go
the scientific road ahead to meet this challenge.     also had become a topic of controversy. Reports       all the way back to neural crest cells? In other
They also portray some of the likely benefits         had begun to trickle into the scientific literature   words, why study the Book of Genesis? Why
of this research to the nation’s public health.       that neural crest cells in some fish gave rise to     not just cut to the Book of Revelations and fully
These include a detailed picture of where the         neurons and nerve fibers of the cranium, while        formed human tissues?
molecular glitches might arise in the system,         those in certain salamanders were proposed to
for example, to cleft a lip, omit a tooth bud or                                                            Think of it like this. You wouldn’t understand
                                                      produce cartilage of the head and dentin forming      the meaning of Tolstoy’s “War and Peace” by
malform a bone. By knowing the most frequent          cells of the teeth. Many biologists claimed this
problem spots and, more generally, how healthy                                                              flipping to the last few chapters. The same is true
                                                      was preposterous.                                     here. You’ve got to start as close to the beginning
craniofacial structures are made, scientists will
                                                                                                            as possible to follow the biological narrative and,
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hopefully, tease out its underlying molecular           fertilized egg. Without giving any obvious hints,        Paul Trainor
logic and morphological patterns.                       that lone cell gives rise to structures and faces as
                                                        diverse as those of a human being, a finch and a
What are some of the early features of                  giraffe.
the narrative?
Well, the initial generation of neural crest cells.     And yet, as complex as craniofacial
It’s really quite fascinating. The early embryo         development is, it usually is completed
forms as three distinct layers of tissue – the          without a hitch.
exterior ectoderm, the middle mesoderm, and             That’s right, craniofacial development goes
the internal endoderm. By day 19, the interaction       right in the vast majority of cases. What’s
of ectoderm and mesoderm produces the neural            interesting is the same genes that are used early
plate, a precursor of the central nervous system.       in development also are used later in the process
                                                        and at multiple times. It seems to be a reiterative
And neural crest cells form along the
                                                        process during which you have important genes
neural plate?                                           that are first used to specify a cell type and then
Exactly. The interaction between ectoderm and
                                                        later that same gene might be used to tell it to
mesoderm is a classic mode of embryonic tissue
                                                        differentiate into a tooth, bone or jaw cell. It’s
formation. That’s why the lessons learned here
                                                        fascinating to realize that the toolkit is not as vast
will have relevance to understanding tissue
                                                        as we once thought it must be. It’s the way that
formation elsewhere in the body. That’s also why
                                                        toolkit is deployed that proves to be especially
it’s essential to define the molecular machinery
                                                        important.                                                              Dr. Paul Trainor
within the neural crest cells that prompt them
                                                                                                                     Stowers Institute for Medical Research
to migrate. In other words, which molecular             Has the genetic activity of neural crest                             Kansas City, Missouri
gears and sprockets turn on and off to enable           cells during the developmental process
neural crest cells to transition from ectoderm to       been catalogued?                                         Has the push for multidisciplinary
mesoderm? How does this transition enable them          We’re getting there. With the full genetic               research been a positive change in the
to loosen from the neural tube and migrate, for         complement, or genomes, of various species now           field?
example, to the heart or the cranium? And, of           determined, the rate of identifying genes involved       Oh, definitely. I would say that combining
course, in the context of cranial neural crest cells,   in making a head or a heart has increased                disciplines has helped in the last few years to
it’s essential to understand how these cells at first   exponentially. It’s left us wading through a huge        increase the scale and pace of the research in
produce what appears to be the same generic,            amount of data. That’s exciting in that so many          general. You can see that with the NIH Roadmap
undifferentiated facial primordial in vertebrate        more pieces to the puzzle are spread out on the          Initiative. The Roadmap, because of its larger
species. And yet, neural crest and the surrounding      table. The problem is this heavy volume makes            scope, interdisciplinary emphasis and often the
ectodermal cells generate these dynamic                 assembling the puzzle more complex. If I’m               uniqueness of its projects, can open up very
development programs that produce vertebrate            dealing with 500 or 1,000 genes to figure out how        rapidly numerous unexpected avenues of study
structures as distinct as the beak of a toucan, the     they work together to create a cell type or render       and thus a number of spinoff projects. In neural
tusk of a boar or the venom-producing salivary          a neural crest cell migratory, I might be really         crest research, we’re already benefiting from this
gland of a rattle snake.                                puzzled. If I have a colleague who is looking            progress.
your group is looking comparatively                     at it from an opposite approach but happens to
                                                        identify a subset of those genes, we can take
                                                                                                                 How so?
up and down the evolutionary ladder                                                                              People no longer look at neural crest cells
                                                        those 1,000 candidate genes and cut them to 10
not only at vertebrates but also                        and begin thinking about communication nodes
                                                                                                                 and facial development from a single-gene
invertebrates, or more primitive                                                                                 perspective. That had long been the norm, largely
                                                        and signaling networks. What I’m hoping is that
creatures that lack a spinal column and                                                                          because of technological limitations. People now
                                                        by putting these groups together, we can narrow
thus a head. Why?                                                                                                have a better set of investigative tools at their
                                                        down the key players more quickly. There’s
That’s where many of the answers to vertebrate                                                                   disposal and are broadly defining the different
                                                        going to be common themes running through
evolution will be found. People tend to be so                                                                    gene regulatory changes in neural crest cells.
                                                        this. Unless you do something comparatively, you
human-centric, and because of that, vertebrate-                                                                  They also are taking the next biological step
                                                        can’t see those threads.
centric. But if you can piece together and                                                                       and defining the protein signaling networks that
understand some of the evolutionary changes that        And these multidisciplinary groups have                  must be activated for initial crest cell formation,
occurred through the millennia from invertebrate        been formed and continue to be?                          and those that subsequently trigger their three-
to vertebrate, they can be extremely informative        That’s right. For example, the NIDCR soon will           dimensional patterning. That will also impact our
in telling us how something as complex as a             launch its FaceBase Project. It will bring together      understanding of neural crest cell evolution.
human head is assembled. In short, we need              scientists of various research backgrounds and
                                                                                                                 But neural crest cells are only a part of
to listen to the biology, not impose our own            establish collaborative consortia that focus on
                                                        specific sequences of craniofacial development.
                                                                                                                 the developmental story. There are also
mechanistic thoughts and metaphors upon it.
                                                        That will be very constructive. Our best science         the pharyngeal arches that they colonize
And by listening to the biology, it also                is ahead of us, and as more of the metaphorical          and which serve as an inductive template
will help to explain where things go                    pieces to the neural-crest puzzle are discovered,        – the facial primordial – for craniofacial
wrong to cause a malformation, say a                    I think fitting them into a coherent biological          development.
cleft lip?                                              picture of craniofacial development will have            That’s right, it’s a two-way street. The neural
Sure. I think a lot of the answers to birth defects     profound implications for human health and               crest cells certainly don’t exist in a vacuum.
will lie in the early stages of craniofacial            disease.                                                 Historically, we used to think that neural crest
development. One of the things that I’m very                                                                     cells did a lot, basically by themselves. I’d say
interested in is the gene regulatory networks in                                                                 that if one thing has changed dramatically in
neural crest cells that help to initiate this self-                                                              the field over the last five to 10 years, it’s been
assembly machine that forms a head. You start                                                                    this recognition that, yes, neural crest cells have
development in all species with a single-cell                                                                    species-specific programming information. But a

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lot of what they do is dependent on which tissues       When can neural crest cells first be                       some people have found that folic acid somehow
they contact during their migration and which           detected during embryonic development?                     confers better viability to neuroepithelial cells
signals are received when they reach their final        In the mouse and chick, we’ve gone all the                 and can reduce the incidence of neural tube
resting place.                                          way back to the induction process, which is the            defects. That’s the approach that we’re taking.
                                                        earliest relevant time point [embryonic Day 8              We start with a specific syndrome, try to identify
A view of the neural plate and migrating                                                                           its cause, test whether the mechanism may be
                                                        in the mouse, 1.5 in the chick]. If we went back
cranial crest cells.                                                                                               common to similar syndromes, and see if we can
                                                        any further, we’d see things that might influence
What i’m wondering, though, does the                    neural crest formation secondarily, such as the            find a way either to chemically or genetically
facial primordial serve as the rough                    development of the neural plate. But they may              rescue the problem.
blueprint of a vertebrate head?                         not be particularly relevant to the actual induction
That may well be. If you look at the different
                                                                                                                   But, as you said, nobody will get
vertebrate species, there are tremendous                                                                           anywhere without doing the biology?
similarities in the initial formation and migration     so, in these species, you can track neural That’s right. Every day presents a new challenge,
of neural crest cells into the pharyngeal arches,       crest cells from just about point A to Z of but we enjoy our work and its potential to benefit
also called the branchial arches in fish. There’s       the developmental process?                       substantial numbers of people worldwide.
no doubt about that. But if you fast-forward the        Yes, exactly. What we can’t do is tackle that in Part ii: Tooth development
developmental process and look at the diversity         humans for technical and ethical reasons. What             Is it possible to build a tooth? That’s a question
of facial structures that arise across the vertebrate   we do know, if you think about the different               that many giants of 20th century dental research
spectrum, they are dramatically different from          phases of neural crest development – whether it            no doubt considered, and it’s a conceptual puzzle
the trunk of an elephant to the tusks of a boar. So     be the formation, migration, differentiation phase         that continues to capture the imaginations of the
what is highly conserved in nature is this early        – if an anomaly arises in any one of those phases,         nation’s oral health scientists. But there is a key
basic blueprint of facial development, and then         you can end up with a very different craniofacial          difference between the musings of then and now.
the diversification themes that take place beyond       malformation.                                              Today’s scientists possess for the first time the
that time point.                                                                                                   needed laboratory tools to plumb the molecular
                                                        For example?
When you say “diversification themes,”                  Well, there a number of recognized neural crest-           depths and developmental biology of tooth
                                                        derived malformation syndromes. I’m talking                formation, and some already have begun to do so
that’s where neural crest cells play such
                                                        about potentially devastating conditions such              in earnest.
a major role?
Correct. Neural crest cells are endowed with            as Treacher-Collins syndrome or DiGeorge                   The research follows two broad but
an innate plasticity, or an ability to make             syndrome. What’s clear is these often-severe               complementary tracks. One seeks to define in
developmental modifications. That means the             syndromes arise within the first eight weeks of            sequential detail the genetic programs underlying
genetic program wired into the neural crest             pregnancy. At the moment, there is no way that             tooth development and, moving to the next
cells don’t need to be modified at the neural           we can detect or visualize them in people during           biological level of activity, to map the protein
tube, that is, the very front end of their life         these early, in utero stages based on morphology           biocircuitry in tooth-forming cells that carry
cycle. The modifications can occur throughout           alone. I think an exceptionally skilled                    out the genetic program. This research delves
the developmental process. By that, I mean              sonographer, even if he or she was specially               into the genetics of the initial tooth placode, a
cranial neural crest cells can be influenced by         trained to detect craniofacial anomalies, wouldn’t         thickened patch of ectoderm near the fetal head
molecular factors during their migration to the         necessarily be able to do it with 100 percent              that arises as migratory neural crest cells arrive
pharyngeal arches. Or they might arrive there           accuracy, even at 22 to 25 weeks of pregnancy.             early in development. It then tracks the sequential
at a new position, where they have multiple             I should note that even if one could recognize a           development of the tooth cap, the tooth bud
tissue interactions that modify their location,         potential problem, many craniofacial syndromes             and ultimately, the maturation of the individual
orientation, and ultimately their fates.                are quite similar and overlap in their phenotypes,         dental tissues therein, from enamel down to the
                                                        or visible manifestations. They also vary in               cementum of the tooth root.
                                                        severity from child to child. So the precise               The other path aims to take this fundamental
                                                        identification of a specific condition still requires      information and, like a minimalist artist,
                                                        genetic confirmation. It can’t be done visually.           deconstruct the complexity of tooth development
                                                        What needs to change to turn back the                      and define its essential molecular requirements.
                                                                                                                   By stripping away the redundancies and
                                                        detection clock?
                                                                                                                   other non-essential molecular chaff of the
                                                        Well, it’s incredibly complex. I guess one is
                                                                                                                   process, scientists hope to match or possibly
                                                        the development of improved technologies to
                                                                                                                   improve upon nature’s instructions to engineer
                                                        visualize the very early embryo.
                                                                                                                   replacement tissues for damaged teeth.
                                                        But that’s only part of it. I think it is very difficult
                                                                                                                   Offering their perspectives on the road ahead
                                                        at that early stage to say whether something
                                                                                                                   are two NIDCR grantees. They are: Dr. Richard
                                                        looked unusual and needed to be monitored and
                                                                                                                   Maas, a scientist at Brigham and Women’s
                                                        then to try to figure out what it was that was
                                                                                                                   Hospital and Harvard Medical School in Boston,
                                                        abnormal. It’s not always so clear.
                                                                                                                   and Dr. Malcolm Snead, a scientist at the
  Neural crest cells are endowed with innate
                   plasticity.                          How will clarity be reached?                               University of Southern California in Los Angeles.
                                                        I would say the key is building on the recent
And it’s this plasticity that leads to                  progress in biology. If we have good mouse
diversity?                                              models of individual diseases, we can take all
That’s right. The plasticity allows such                of the genetic network information for neural
tremendous variation. If everything was rigidly         crest patterning, migration and differentiation
preprogrammed when neural crest cells form              and pinpoint the origin of the problem. If it turns
in the neural tube, you certainly wouldn’t have         out to be something as simple as a wave of cell
the same flexibility. Vertebrate faces might look       death – the neural crest cells are being killed
relatively the same from one species to the next.       off – then the simplistic idea is to find something
                                                        that will keep them alive, in the same way that
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Richard Maas                                          at these concentrations and in this particular       a major investment has been made over the last
                                                      combination. I need to couple them with a            decade or so to perform comparative analyses
                                                      scaffold of extracellular matrix materials X, Y      among species and tease out these evolutionary
                                                      and Z. And because this information is based on      motifs.
                                                      how the tooth normally forms, if we reconstruct
                                                      those types of parameters as best we’re able in
                                                                                                           But on another level, how detailed will
                                                      vitro, we should have a molecular blueprint that     the instruction manual need to be? in
                                                      will yield a structure that approximates a tooth.”   other words, do we need to recapitulate
                                                                                                           all of the moving parts and redundancies
                                                                                                           that are built into the system? or
                                                                                                           can the process be streamlined in the
                                                                                                           laboratory and remain functional?
                                                                                                           The answer is we probably don’t need to know
                                                                                                           all of the moving parts. There are some basic
                                                                                                           organizing principles at work in the tooth bud
                                                                                                           that can be mastered and hopefully exploited to
                                                                                                           form enamel, dentin, cementum and the other
                                                                                                           constituent parts of the tooth. That means we
                                                                                                           don’t need to account for every last gene in the
                                                                                                           human genome to build a tooth, and that’s why
             Dr. Richard Maas                                                                              this is a doable task.
     Brigham and Women’s Hospital and
          Harvard Medical School                                                                           How many genes would make the cut?
                                                      Extra (supernumerary) teeth can be induced           Well, although there are roughly 23,500 genes in
           Boston, Massachusetts
                                                      to grow in the jaws of mice by selective             the human genome, probably only one-tenth of
As a part of the niH Roadmap initiative,              inactivation of a single gene, Apc. A normal         those are expressed during tooth development.
you have begun a project that, in part,               mouse first molar is shown (above) for               That is to say, they satisfy the condition of being
explores tooth development. Could you                 comparison.                                          necessary or sufficient.
tell us about it?                                     Below, the two left teeth are normal upper and
                                                                                                           And of those genes, some likely will be
Sure. The project focuses on three structures: the    lower first molars, while the two right teeth
tooth, pancreatic islet cells and the heart valve.    (arrows) are supernumeraries.
                                                                                                           more critical than others?
                                                                                                           That’s right. Not all genes and proteins that
The central premise here is we now know enough
                                                                                                           plug into a developmental pathway are of equal
about organ development to use this knowledge
                                                                                                           importance. This relates to the structure of
base as a template to assemble a far more
comprehensive biological picture of the process.
you want to put more meat on the bone?                                                                     How so?
                                                                                                           There are two general types of biological
Exactly. The program’s acronym is SysCODE,
                                                                                                           networks hard-wired into our cells. One is
which stands for Systems-Based Consortium for
                                                                                                           called a universal random network, where every
Organ Design and Engineering.
                                                                                                           component, or node, is equal in importance
so, it’s a systems biology approach, or                                                                    and weight. The second and more prevalent
studying the cell as an integrated system                                                                  form is called a scale-free network. In scale-
of biological circuits and data processing?                                                                free networks, not all nodes are created the
Well, the systems-based aspect arises because                                                              same. There are very important centralized
we want to integrate the various data sets that                                                            nodes, or hubs, that act as convergence points
the new generation of research tools now can                                                               and processing centers for incoming biological
                                                      The magnification in the first image is twice        information. Think of the spoke-and-hub system
generate. These include comprehensive gene
                                                      that in the second image. From: Kuaraguchi,          in aviation. If you identify the hubs – the Chicago
expression profiles; extensive catalogues of
                                                      Wang et al., PLoS Genetics 2, e146, 2006.            O’Hares – it’s possible to predict the behavior of
protein expression, chip-on-chip analyses to
figure out where transcription factors bind in the    How does a tissue engineer do it today?              the system to a large extent and without needing
genome; assembling data on common inherited           Well, the current paradigm for tissue engineering    to piece together every single element of the
genetic alterations; and logging the results of       consists of taking Factor X, adding it to some       network.
RNAi experiments to inhibit an individual gene’s      cells and seeing what happens. I’m in no way         What might these predictions reveal?
expression and thus study its function and thereby    denigrating that approach. I think it’s been         Let me give you an example. We study a gene
dissect relevant signaling pathways within the        incredibly successful. But it is empiric, and a      that, if inactivated, results in the formation of
system.                                               molecular blueprint would be extremely helpful.      supernumary, or extra, teeth in the mouse. That
What will this data integration produce?              in generating the data sets, on one level,           suggests that this gene and its protein product
Our hope is a coherent molecular blueprint to         wouldn’t you want to tease out the                   are very high up in the regulatory cascade that
build a tooth. The idea is, once the computer and                                                          controls tooth development. By manipulating that
                                                      evolutionary biology of the tooth? By
genome scientists have assembled this large body                                                           protein, you wouldn’t necessarily have to control
                                                      analogy, a mechanic needs to know the                all of the others that are activated subsequently,
of information in an intelligent format, it will be
                                                      make and model of an automobile before               or downstream, of it. Because that master gene
amenable for tissue engineers to use.
                                                      lifting up the hood.                                 would take care of them for you. You see?
How would they use it?                                You certainly want to know how a tooth or any        So, this shows the great simplification that is
The set of instructions would be in a user-friendly   part of the body came to be. So, yes, I agree. And   possible as some genes turn on entire programs of
format for a scientist to say, “Okay, I need to add   that information is being assembled. From DNA        downstream events.
Factors A, B and C in this particular sequence,       sequencing projects to improved mouse models,

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Are there other basic organizing                       interested in day six or seven of gestation,          structurally than its individual parts, in this case,
principles?                                            although I think early development is very            elongated hydroxyapatite crystals. Enamel is
There’s a corollary principle. I would call it the     interesting. My research focus is on the problems     a fascinating tissue. I’m actually sitting here
principle of autonomy. By that I mean, if an early     of tissue specification during late gestation and     holding a chunk of hydroxyapatite in my hand.
tooth germ reaches a certain developmental stage,      early postnatal development.                          If you made a tooth out of what’s in my hand,
it will continue to develop all the way to the                                                               it would fracture and fall apart in a matter of
                                                       How do these problems flow into building              days. Its toughness, hardness and elasticity
latter stages of mineralization. There’s actually a
                                                       a tooth?                                              really are quite different than the hydroxyapatite
precedent for that. Dr. Paul Sharp and colleagues
                                                       In our case, the focus is on learning to engineer     in the enamel of my teeth. Some of that has
at Guy’s Hospital in the UK showed some time
                                                       new tissue to replace damaged or diseased tooth       to do with the nanoscale that nature works to
ago that if they took what’s called a cap-stage
                                                       structures.                                           weave hydroxyapatite crystals into the patterned
tooth germ and grafted it into the jaw of an adult
mouse, it will in fact develop much, much further.     Why engineer?                                         structure that we know as tooth enamel. Another
                                                       Let me back up a bit. Biology is now in a golden      small part of that is some residual amount of
That would mean we don’t necessarily                                                                         protein. It’s maybe 5/10 of a percent of protein
                                                       age of discovery. We can knock out a specific
have to worry about mastering all                      gene, modify another gene and ask a variety of        dry weight. It’s likely retained for a very specific
stages of tooth development. once a                    profound questions about the circuitry of the cell    function.
developmental tipping point is reached,                that just weren’t on the table a decade or so ago.
biology could take care of the rest?
That’s right.                                          For example?
                                                       Well, you could ask what happens systemically if
What impact might this and related                     you remove 100 percent of transforming growth
work have on practitioners in the coming               factor X? Does the cell – the biological system
years?                                                 – have the ability to compensate for the loss via
Well, let me just say that current prosthetics work    a redundant signal? If there’s no compensation
relatively well. But millions of Americans still       and thus the effect is uniform within the system,
lose a significant number of teeth during their        what then happens downstream when the circuit
lives, and dental disease remains a significant        is shut down? It’s kind of like a caveman holding
health problem. So, if we could generate a             a pocket watch. You smash the pocket watch and        After injecting artificial bioactive
biomimetic substitute, it would be welcomed.           say, “Great, look at all of these parts in it.” But   nanostructures, the mouse incisor expresses
To do that at a reasonable cost and with good          can you reassemble the watch? The next step is        the protein integrin alpha-6.
efficiency, I think you’re looking at least a decade   to go back and say, “Okay, I know that I need this
                                                                                                             The protein helps to form the enamel matrix.
into the future. On the other hand, if you could       piece, but how far can I turn it down,” so that it
generate enamel matrix in a test tube from cells       functions at 10 percent of its normal level and
that you’ve programmed, that would be very             still get an outcome?
exciting. How that would figure into clinical
                                                       Addition by subtraction?
practice, dentists no doubt would decide. But,
                                                       Right. If you’ve identified all of the pieces, can
clearly it would be a wonderful natural product.
                                                       you also define the ones that you don’t need? It’s
Malcolm snead                                          a matter of relevance, and that is now framed
                                                       within the context of our expanded scale of
                                                       discovery. What I mean is we used to try to
                                                       understand how the cell worked at some level
                                                       when we could perform a Western blot assay and
                                                       detect a protein. We advanced to a Northern blot
                                                       assay to process RNA, and that gave us greater
                                                       sensitivity to quantify gene expression. In the       Green fluorescent proteins illuminate cells
                                                       1990s, we entered a PCR state of affairs that         in a three-dimensional matrix of artificial
                                                       enabled us to look at five or six molecules in a      bioactive nanostructures.
                                                       cell. Now you must start pulling out the noise,
                                                       the chaff in the system. What is relevant? And
                                                       what is spurious noise? It’s oftentimes a matter
                                                       of understanding what you know relative to how
                                                       you think you need to know it.
                                                       What about something as complex as a
                                                       tooth root?
                                                        It’s a four-in-one proposition with dentin, pulp,
                                                       cementum and the periodontal ligament. It
             Dr. Malcolm Snead                         represents a challenge, but certainly a worthy
       University of Southern California               one. If you can understand root formation, you
           Los Angeles, California                     have a much better handle on regenerating a           A close-up of dental enamel.
                                                       major cause of tooth loss in adults, which is the
The term “building a tooth” suggests                   loss of supporting bone and ligament. But what’s      And it’s retained as a remnant of the
creating a bicuspid or incisor from                    important here is this is a challenge that we now     original protein matrix?
scratch. But that’s not the focus in your              can productively wrap our minds around.               Right. Even though the tooth erupts into the
laboratory?                                                                                                  oral cavity as a white, mineralized fossil, it
Most of my interest and expertise
                                                       What about regenerating enamel, one of                was not a fossil during its formation. Before
developmentally lie downstream of those                your major research interests?                        the hydroxyapatite crystals elongated, properly
initiating events. In other words, I’m not             Enamel is a tissue in which the whole is greater

Elite CME                                                                                                                                                   Page 5
oriented themselves and formed mature enamel,           monitoring 40 channels of data coming out of          William giannobile
they were seeded in an extensive protein matrix         the cell simultaneously, from their cell receptors
that served as a developmental lattice. All of the      to their oxidative state. You could see lots
rules that apply to changes in gene expression,         of different parameters of cell biology being
control of protein expression, response of              reported in a single cell instead of looking at
different signaling molecules through membrane-         a thousand cells and averaging their behavior
mediated receptor events and secondary signals.         for one parameter. You can just imagine what
All of those are happening. Enamel is very, very        that means. Suddenly you must ask, “Have we
much alive as it’s being made.                          been measuring the tops of mountains? There’s
                                                        a much wider range to how cells respond. We
But can you go all the way back                         have to see a 20-fold change in its activity before
and track the assembly of, say, the                     we even start to say we can measure and work
amelogenins in forming the protein                      with it. When, in fact, the system is much more
matrix?                                                 sensitive, it may be changes of 20 percent that
Absolutely. In fact, there are 16 different             make differences. But we ignore them because
isoforms, or types, of amelogenin. We work              we don’t see them.
on them in in vitro analyses, and that tells you
certain things. But then you must go back               Part iii: Periodontal disease: Engineering
to the organism and say, “In the context of             the future of care
the organism, does it work this way?” That’s            In the 1950s, soon after NIDCR’s founding,
where the approach to genetic engineering –             millions of Americans often flipped on their
the simplicity of a biological outcome as your          black-and-white tube televisions and watched                       Dr. William Giannobile
measure – is very appealing. If you can achieve         commercials that warned of a tongue-twisting                       University of Michigan
the same outcome with a lot less moving parts,          condition called gingivitis. As the ads warned,                     Ann Arbor, Michigan
it suggests that you understand how the system          gingivitis was step one on the road to chronic
                                                                                                              you oversee your own laboratory and
works and know its critical parts.                      gum, or periodontal, disease and tooth loss.
                                                                                                              head a clinical research center at the
How’s the engineering going?                            Today, researchers now know that gingivitis does      University of Michigan. You also find the
Quite well. Right now, I’m working on a                 not necessarily lead to advanced periodontal          time to see patients in private practice?
manuscript that produces almost a two-order             disease. However, a confluence of factors can         I’m also a practicing periodontist, and I continue
reduction in simplicity in proteins of the              induce chronic inflammation of the gingiva in         to treat patients in a private practice here in Ann
amelogenin class. We used a genetic knock-in            some people. These factors include lifestyle          Arbor.
strategy that ends up producing an enamel that          choices, such as an addiction to tobacco; diabetes
has essentially characteristics that are within 20      or another underlying health condition that           so you’ve both seeded and directly
percent of the natural enamel. So I’ve made this        compromises one’s ability to heal; a susceptibility   benefited from the research?
enamel with 16 times less alternative proteins          to gingival infections; and an over-reactive          I think so. As a practitioner, I’ve benefited from
participating. And yet, the system seems to work        immune system. If left unchecked, periodontal         the advancements in biomaterials research,
adequately. Or within 95 percent of the expected        disease gradually will degrade the four tooth-        various bone grafting techniques, guiding tissue
values. So this question of how far can we go is        supporting tissues of the periodontium – gingiva,     membranes that separate the bone from the
one that I share with the rest of the team here at      periodontal ligament, cementum and bone.              connective tissues, and anti-infective therapies
University Southern California and numerous             As the television ads from the 1950s correctly        to arrest or slow the progression of periodontal
labs around the world.                                  concluded, advanced periodontal disease will          disease.
                                                        lead to tooth loss.
And across scientific disciplines.                                                                            But there’s still a ways to go?
                                                        Today, a trip to the periodontist typically entails   That’s right. Periodontal treatment today remains
Yeah, I think a lot of people in materials sciences,
                                                        anti-infective therapy coupled with scaling and       fairly unpredictable in terms of getting stable,
engineering and nanotechnology get quite excited
                                                        planing of the inflamed tissue. Periodontists         long-term results. That’s especially true for
about it. Making a mineral that behaves in the
                                                        also have been eager to employ the latest             regenerating the various parts of the periodontium
way that enamel does, or the way that the enamel
                                                        biological discoveries to regenerate damaged          – bone, ligament, cementum and mucosa. But
actually bonds to the underlying dentin and
                                                        gingiva, ligament and bone. Although today’s          there have been some nice advancements,
dentinoenamel junction, or DEJ, is a phenomenal
                                                        tissue regeneration techniques remain works           and I just mentioned a few of them. I think
piece of engineering. When I speak to my
                                                        in progress, research on this front continues to      the combination of research progress and the
engineering colleagues, they would like to know
                                                        progress nicely. Most scientists are optimistic       continued unpredictability of treatment has to
about the DEJ. How does the enamel stay on the
                                                        that tissue engineering, with its sophisticated       some extent shifted the periodontist’s role.
                                                        mix of biology and chemistry, will be more
That’s of real significance to dentists.                predictable in the years ahead. To present the        How so?
Right, if you could replicate a dentino enamel          research themes are two scientists with long and      About 20 years ago, most restorative dentists
junction (DEJ), it would be a first step toward         productive records of accomplishment in this          would contact periodontists with referrals and
ensuring that fillings lasted longer. Restorations      area: Dr. William Giannobile, a researcher at the     say, “Do your best. See how many more years
usually fail at the interface. It’s not the filling     University of Michigan in Ann Arbor; and Dr.          you can help this patient eke out of these teeth.”
itself. It’s the bond of the materials. … If a glass-   Pamela Robey, an NIDCR scientist in Bethesda,         Now, the mindset is much different. Because
like ceramic material is more compatible with           Maryland.                                             of the unpredictability of regeneration and the
the dentin, you can increase the longevity of the                                                             challenge of controlling a chronic immune
restoration.                                                                                                  response, many practitioners don’t want to run
                                                                                                              the risk of trying to save the teeth. Many advise
And the data are pouring in.                                                                                  their patient to have the questionable teeth
Yes, that’s right. It’s pouring in all areas of                                                               removed and replaced with dental implants. But
biology. I was at a nanotechnology meeting                                                                    as a researcher and periodontist, I continue to
recently where people were talking about                                                                      support the profession’s founding principles to

Page 6                                                                                                                                                  Elite CME
save teeth whenever possible. For that reason,       so how do you make tissue regeneration                Pamela Robey
I see a lot of areas that we need to explore to      more predictable?
develop more predictable therapies, especially       I think interdisciplinary collaborations hold the
when regenerating the damaged tissues of the         key. We need scientists with training in infectious
periodontium.                                        disease, biomedical engineering, molecular and
And the biology is there for the taking?             cell biology, genetics, and clinical research.
I think so. You can see it in the scientific         What about technology development?
literature each and every month. You also can      Discovery and technology development typically
see it in the ideas that have entered the clinical go hand in hand. A good example is the progress
research pipeline.                                 in high-resolution imaging techniques. They
For example?                                       produce images of bone damage that are so
Growth factors. Platelet-derived growth factor     accurate, we literally can construct in the
and the bone morphogenetic proteins are both       laboratory three dimensional scaffolds that fit
now FDA approved and have entered into the         perfectly into the periodontal pockets and deliver
clinical arena over the last two years. Although   regenerative factors. This hasn’t yet reached the
these growth factors have sometimes incorrectly    clinic, but it suggests the following scenario: The
been held up as a panacea for tissue regeneration, surgeon images the tooth/bone lesion and says
they are indeed very important advancements.       to the patient, “Okay, I can quickly make this
Keep in mind, though, periodontal disease is an    scaffold, and it will be loaded with growth factors
                                                                                                                          Dr. Pamela Robey
extremely complex condition. Tissue regeneration or stem cells. We’ll just drop it into the defect.”
                                                                                                                     National Institutes of Health
alone is not the answer. We need to push the anti- Right now, the surgeons carve out the decalcified
                                                   bone as best they can. It’s just not efficient.                       Bethesda, Maryland
infective/host modulation side, too, and ensure
that the patient’s immune response doesn’t turn    We talked a moment ago about the                        it’s kind of like reading the old
chronic and self-destructive.                      biology being there for the taking. if the              Testament Book of numbers. The
And that self destruction is of an                   scaffolds and their growth-promoting                  patriarchal stem cell begets sublineages
inherently complex environment?                      cargo now can be more precisely                       of cells.
Absolutely. We essentially have a tooth – an         delivered, that raises the issue of timing.           Right, and this theme is played out throughout
avascular mineralized tissue – that protrudes        you need to drop in the growth factors                the body. We see it in bone and cartilage, and we
through soft tissue, where it is under constant                                                            see it in dentin.
                                                     at the right time and in the right
microbial attack. The tooth is rooted in bone,       sequence.                                             What’s the second defining feature?
anchored by ligament and dependent on                That’s an important point. Researchers have           Self renewal. A stem cell must have the ability
supportive tissues in dentin and cementum.           begun to look at the process in a more systematic     to produce a new generation of stem cells. So, as
These tissues have specific geographic junctions,    way. But defining the biology is even more            they churn out more mature daughter cells, they
abilities to bond and load-bearing qualities.        important from a diagnostic standpoint. Patients      also must produce daughter cells that remain
What’s more, all of this complexity is rolled        respond differently to treatment.                     stem cells. Without self-renewal, the stem cells
into a tight biologic space. We often talk about                                                           that populate a given tissue would die their
millimeters of eroded bone. Millimeters are very                                                           natural deaths and take with them the ability to
significant in the support of teeth. There’s just                                                          regenerate and maintain a tissue structure.
nothing like the periodontium in the rest of the
body.                                                                                                      Why has the definition of stem cell gone
                                                                                                           off in all directions?
                                                                                                           It’s the vagaries of cell culture. Because scientists
                                                                                                           typically study stem cells in a culture dish, they
                                                                                                           describe certain characteristics that may or may
                                                                                                           not relate back to what they do in the body.
                                                                                                           For example?
                                                                                                           Well, two things come to mind. A lot of people
                                                                                                           say that a stem cell is undifferentiated. But
                                                                                                           that may be a misnomer. It may be that a fully
                                                                                                           differentiated cell, under the proper conditions,
                                                                                                           can revert back and become a precursor cell or
                                                                                                           maybe even a more primitive cell like a stem cell.
                                                                                                           As long as a cell has an intact nucleus, nothing is
                                                                                                           really impossible.
                                                                                                           Secondly, some say a stem cell has the ability
                                                                                                           to replicate almost endlessly. But that isn’t
                                                                                                           necessarily the case either. Even the best
                                                                                                           characterized stem cell – the hematopoietic stem
                                                                                                           cell – is not immortal. Each hematopoietic stem
                                                                                                           cell can only repopulate blood cells a certain
                                                                                                           number of times before it becomes exhausted.

   The four research areas that hold the key to a future of periodontal tissue engineering and             How does this “stemness” translate to
                                    regenerative medicine.                                                 the periodontium?
                                                                                                           Let’s start with the periodontal ligament. We

Elite CME                                                                                                                                                Page 7
know it’s possible to take a periodontal ligament        is a major hurdle in trying to construct a root that
and treat it with enzymes to release single cells.       will provide a solid anchor within the jawbone.                                 FACing THE FuTuRE: niDCR
Within that mixed population of cells, there are         And we need to bring a broader array of expertise                            REsEARCHERs oFFER THEiR vision
some that have the ability to recreate fibers that       to the table. We need more people with expertise                                  oF THE 21sT CEnTuRy
look a lot like those in a periodontal ligament.         in bioinformatics, biomaterials, biochemistry and                                   Final Examination Exercises
Whether the fibers can function as a periodontal         clinicians to help us design appropriate animal                                   Choose True or False for questions
ligament I think is still on the table for discussion.   models that mimic a given human disease. There                                1 through 5 and mark your answers on the
These cells were discovered here at NIDCR about          can be a perception that it’s only a tooth. It’s not                              Final Examination Sheet found on
four years ago, and this lead is actively being          going to kill you if you don’t have one. But try                                  page 109 or take your test online at
pursued. It’s also not clear where the cell comes        to tell that to somebody with a bad toothache.                                       www.onlinedentalCE.com.
from and whether it’s truly a stem cell or a useful      Dental problems cut across all aspects of society,
progenitor cell. I think that is something that we       and their solutions potentially benefit everyone.
need to take into consideration.                         Secondly, the mouth is readily accessible, unlike                           1. The interaction between ectoderm and
                                                         the body’s internal organs such as the pancreas                                mesoderm is a classic mode of embryonic
What do you mean?                                        or liver. The lessons learned in the oral cavity                               tissue formation.
Having a stem cell is a wonderful thing.
                                                         might not be a perfect fit in learning to better treat
Knowing about it is a wonderful thing. But the                                                                                                 True                False
                                                         osteoporosis or kidney cancer, but they will have
slightly more committed progenitors also can
do wonderful things. We shouldn’t dismiss them                                                                                       2. Neural crest and the surrounding
just because they don’t self-renew or produce            Conclusion                                                                     ectodermal cells generate the development
more than one cell type. If they’re useful in a          There are many challenges in the study of the                                  programs that produce vertebrate structures
regenerative way, that’s fine. They don’t have to        human molecular genetics, and researchers                                      as distinct as the beak of a toucan, the tusk
be a stem cell to be useful.                             are involved from many different areas and in                                  of a boar or the gland of a rattlesnake.
                                                         many different ways. We have learned from the
What about alveolar bone of the tooth                    interviews above that researchers are confident                                       True                False
socket?                                                  that eventually they will be able to engineer or
Stem cells that make bone have been under study          build a tooth, and will see tissue regeneration                             3. The pharyngeal arches are also called the
since the mid-1990s. Obviously, they have great          or self renewal from stem cells that have the                                  branchial arches in fish.
potential in regenerating the periodontium. If you       ability to produce a new generation of stem
don’t have bone to anchor the tooth, you have                                                                                                  True                False
                                                         cells. Additional scientific progress in the
no foundation. But we really need to know how            neurosciences will have broad implications
this type of bone is different from the axial and        for the diagnosis and treatment of diseases                                 4. Neural crest cells are endowed with
appendicular bone found elsewhere in the body.           and disorders of the craniofacial system. The                                  an innate plasticity but cannot make
They have a different embryonic origin, and              approach to design and fabricate bioceramics                                   developmental modifications.
their properties appear to be slightly different.        to be used in the replacement of human enamel                                         True                False
We don’t know how that is. Nor do we know the            or dentin of the surfaces of teeth is another
impact of these differences. For example, can            scientific breakthrough. The continued study
we take bone marrow from the iliac crest of the                                                                                      5. Tooth enamel is an organism that is dead
                                                         of the fabrication of biomaterials to be used in
pelvis and use it to regenerate craniofacial bone,                                                                                      when it is being made.
                                                         the advances toward repair and regeneration of
including alveolar bone? That’s a huge question,         cartilage, bone, muscle, teeth, (cementum, dentin,                                    True                False
and we really don’t know much about it.                  enamel and periodontal ligament) offers another
What about cementum?                                     focus. Dental professionals are indeed ready to
Well, I just mentioned the periodontal ligament          face the future.
cells. They also make something that appears             Reference
                                                         swww..nidcr.nih.gov/facingthe future.htm National Institute of Dental and
to be cementum. In addition, a number of                 Craniofacial Research
years ago, we took shavings of cementum and
could get cells to grow out of those shavings
in a clonal fashion. When we took the cells,
put them in a scaffold and transplanted them
into our animal model, they formed tissue that
resembled cementum. The problem is we don’t
really know whether cementum is different from
bone. We don’t have any cementum specific
markers to answer that question. It may just
be that osteogenic cells form a cementum-like
structure when they are in close proximity to
dentin-forming cells. So, the boundaries between
cementum and bone are very subtle. It’s difficult
to say that they are truly two distinct entities.
Maybe under the right conditions, cells that
normally would be osteogenic could be made to
be cementogenic.
Are you confident that the regeneration
of the periodontium will be doable down
the road?
I am confident. We have cells that we can begin
to use to try and create a viable tooth. But there                                                                                                                     DOH03FFE11

Page 8                                                                                                                                                                      Elite CME
                    CHAPTER 2                               Š   Selection and use of devices with features    might be occupationally exposed to infectious
guiDELinEs FoR inFECTion ConTRoL                                designed to prevent sharps injury.            materials, including body substances and
                                                            Š   Hand-hygiene products and surgical hand       contaminated supplies, equipment, environmental
                                                                antisepsis.                                   surfaces, water, or air. Dental health care
                   (6 CE HouRs)
                                                            Š   Contact dermatitis and latex                  personnel includes dentists, dental hygienists,
                                                                hypersensitivity.                             dental assistants, dental laboratory technicians
!   Establish the process of educating and
                                                            Š   Sterilization of unwrapped instruments.       (in-office and commercial), students and trainees,
    protecting dental health care personnel.
                                                            Š   Dental water-quality concerns (e.g.,          contractual personnel and other persons not
!   Explain the prevention of transmission of
                                                                dental unit waterline biofilms; delivery      directly involved in patient care but potentially
    blood-borne pathogens.
                                                                of water of acceptable biological quality     exposed to infectious agents (e.g., administrative,
!   Discuss the concerns of hand hygiene.
                                                                for patient care; usefulness of flushing      clerical, housekeeping, maintenance or volunteer
!   Identify protection against spatter by use of
                                                                waterlines; use of sterile irrigating         personnel).
    personal protective equipment.
                                                                solutions).                                   Recommendations in this report are designed
!   Learn how to avoid the risk of contact
                                                            Š   Oral surgical procedures; handling of         to prevent or reduce potential for disease
    dermatitis and latex hypersensitivity.
                                                                community boil water advisories.              transmission from patient to dental health care
!   Emphasize the importance of sterilization and
                                                            Š   Dental radiology.                             personnel, from dental workers to patient, and
    disinfection of patient-care items.
                                                            Š   Aseptic technique for parenteral              from patient to patient. Although these guidelines
!   List the special considerations that should
                                                                medications.                                  focus mainly on outpatient, ambulatory
    be taken with dental handpieces, waterlines,
                                                            Š   Preprocedural mouth rinsing for patients.     dental health care settings, the recommended
    water quality, biofilm, radiology, oral surgical
                                                            Š   Oral surgical procedures.                     infection control practices are applicable to all
    procedures and dental laboratories.
                                                            Š   Laser/electrosurgery plumes.                  settings in which dental treatment is provided.
introduction                                                Š   Tuberculosis (TB).                            Dental patients and workers can be exposed
Infection control and health care epidemiology              Š   Creutzfeldt-Jakob disease (CJD) and           to pathogenic microorganisms including
is the discipline concerned with preventing                     other prion-related diseases.                 cytomegalovirus (CMV), HBV, HCV, herpes
the spread of infections within the health care             Š   Infection control program evaluation.         simplex virus types 1 and 2, HIV, Mycobacterium
setting. As such, it is a practical (rather than            Š   Research considerations.                      tuberculosis, staphylococci, streptococci and
an academic) subdiscipline of epidemiology. It          These guidelines were developed by CDC                other viruses and bacteria that colonize or infect
is an essential (though often underrecognized           staff members in collaboration with other             the oral cavity and respiratory tract. These
and undersupported) part of the infrastructure          authorities on infection control. Draft documents     organisms can be transmitted in dental settings
of health care. Infection control and hospital          were reviewed by other federal agencies and           through:
epidemiology are akin to public health practice,        professional organizations from the fields of          Direct contact with blood, oral fluids or other
practiced within the confines of a particular           dental health care, public health and hospital             patient materials.
health care delivery system rather than directed at     epidemiology and infection control. A Federal          Indirect contact with contaminated
society as a whole.                                     Register notice elicited public comments that              objects (e.g., instruments, equipment or
Infection control concerns itself both with             were considered in the decision-making process.            environmental surfaces).
prevention (hand hygiene/hand-washing,                  Existing guidelines and published research             Contact of conjunctival, nasal or oral mucosa
cleaning/disinfection/ sterilization, vaccination,      pertinent to dental infection control principles           with droplets (e.g., spatter) containing
surveillance) and with investigation and                and practices were reviewed. Wherever possible,            microorganisms generated from an infected
management of a demonstrated or suspected               recommendations are based on data from well-               person and propelled a short distance (e.g., by
spread of infection within a particular health care     designed scientific studies. However, only a               coughing, sneezing or talking).
setting (e.g., outbreak investigation). It is on this   limited number of studies have characterized           Inhalation of airborne microorganisms that
basis that the common title being adopted within        risk factors and the effectiveness of prevention           can remain suspended in the air for long
health care is “infection prevention and control.”      measures for infections associated with dental             periods.
                                                        health care practices.                                Infection through any of these routes requires that
This course consolidates recommendations for
preventing and controlling infectious diseases and      Some infection control practices routinely used       all of the following conditions be present:
managing personnel health and safety concerns           by health care practitioners cannot be rigorously      A pathogenic organism of sufficient virulence
related to infection control in dental settings. It:    examined for ethical or logistical reasons. In the         and in adequate numbers to cause disease.
 Updates and revises previous CDC                      absence of scientific evidence for such practices,     A reservoir or source that allows the pathogen
    recommendations regarding infection control         certain recommendations are based on strong                to survive and multiply (e.g., blood).
    in dental settings.                                 theoretical rationale, suggestive evidence or          A mode of transmission from the source to
 Incorporates relevant infection control               opinions of respected authorities based on clinical        the host.
    measures from other CDC guidelines.                 experience, descriptive studies or committee           A portal of entry through which the pathogen
 Discusses concerns not addressed in previous          reports. In addition, some recommendations                 can enter the host.
    recommendations for dentistry. These updates        are derived from federal regulations. No               A susceptible host (i.e., one who is not
    and additional topics include:                      recommendations are offered for practices for              immune).
    Š Application of standard precautions               which insufficient scientific evidence or lack of     Occurrence of these events provides the chain of
         rather than universal precautions.             consensus supporting their effectiveness exists.      infection. Effective infection control strategies
    Š Work restrictions for health care                                                                       prevent disease transmission by interrupting one
         personnel (HCP) infected with or                                                                     or more links in the chain.
                                                        In the United States, an estimated 9 million
         occupationally exposed to infectious
                                                        persons work in health care professions,              Previous CDC recommendations regarding
                                                        including approximately 168,000 dentists,             infection control for dentistry focused primarily
    Š Management of occupational exposures
                                                        112,000 registered dental hygienists, 218,000         on the risk of transmission of blood-borne
         to blood-borne pathogens, including post-
                                                        dental assistants and 53,000 dental laboratory        pathogens among dental care personnel and
         exposure prophylaxis (PEP) for work
                                                        technicians. In this report, dental health care       patients and use of universal precautions to
         exposures to hepatitis B virus (HBV),
                                                        personnel (DHCP) refers to all paid and unpaid        reduce that risk. Universal precautions were
         hepatitis C virus (HCV); and human
                                                        personnel in the dental health care setting who       based on the concept that all blood and body
         immunodeficiency virus (HIV).
Elite CME                                                                                                                                                  Page 9
fluids that might be contaminated with blood         retraction devices) are the primary strategies       Review of science related to dental
should be treated as infectious because patients     for protecting dental workers and patients.          infection control
with blood-borne infections can be asymptomatic      Where engineering controls are not available or      Personnel health elements of an infection
or unaware they are infected. Preventive practices   appropriate, work-practice controls that result in   control program
used to reduce blood exposures, particularly         safer behaviors (e.g., one-hand needle recapping     A protective health component for dental health
percutaneous exposures, include:                     or not using fingers for cheek retraction while      care personnel is an integral part of a dental
 Careful handling of sharp instruments.             using sharp instruments or suturing), and use        practice infection control program. The objectives
 Use of rubber dams to minimize blood               of personal protective equipment (PPE) (e.g.,        are to educate workers about the principles of
     spattering.                                     protective eyewear, gloves and mask) can prevent     infection control, identify work-related infection
 Hand washing.                                      exposure. In addition, administrative controls       risks, institute preventive measures and ensure
 Use of protective barriers (e.g., gloves,          (e.g., policies, procedures and enforcement          prompt exposure management and medical
     masks, protective eyewear and gowns).           measures targeted at reducing the risk of            follow-up. Coordination between the dental
                                                     exposure to infectious persons) are a priority       practice’s infection control coordinator and other
The relevance of universal precautions to other
                                                     for certain pathogens (e.g., M. tuberculosis),       qualified health care professionals is necessary to
aspects of disease transmission was recognized,
                                                     particularly those spread by airborne or droplet     provide dental workers with appropriate services.
and in 1996, CDC expanded the concept and
                                                     routes.                                              Dental programs in institutional settings,
changed the term to standard precautions.
Standard precautions integrate and expand the        Dental practices should develop a written            (e.g., hospitals, health centers and educational
elements of universal precautions into a standard    infection control program to prevent or              institutions) can coordinate with departments that
of care designed to protect health care personnel    reduce the risk of disease transmission. Such        provide personnel health services.
and patients from pathogens that can be spread       a program should include establishment and           However, the majority of dental practices are
by blood or any other body fluid, excretion or       implementation of policies, procedures and           in ambulatory, private settings that do not have
secretion.                                           practices (in conjunction with selection and         licensed medical staff and facilities to provide
                                                     use of technologies and products) to prevent         complete on-site health service programs. In such
Standard precautions apply to contact with:
                                                     work-related injuries and illnesses among dental     settings, the infection control coordinator should
                                                     care workers as well as health care-associated       establish programs that arrange for site-specific
 All body fluids, secretions and excretions
                                                     infections among patients. The program should        infection control services from external health
    (except sweat), regardless of whether they
                                                     embody principles of infection control and           care facilities and providers before workers are
    contain blood.
                                                     occupational health, reflect current science         placed at risk for exposure. Referral arrangements
 Nonintact skin.
                                                     and adhere to relevant federal, state and local      can be made with qualified health care
 Mucous membranes.
                                                     regulations and statutes. An infection control       professionals in an occupational health program
Saliva has always been considered a potentially      coordinator (e.g., dentist or other dental health    of a hospital, with educational institutions or with
infectious material in dental infection control;     worker) knowledgeable or willing to be trained       health care facilities that offer personnel health
thus, no operational difference exists in clinical   should be assigned responsibility for coordinating   services.
dental practice between universal precautions and    the program. The effectiveness of the infection
standard precautions.                                control program should be evaluated on a day-        Education and training
                                                     to-day basis and over time to help ensure that       Personnel are more likely to comply with an
In addition to standard precautions, other
                                                     policies, procedures and practices are useful,       infection control program and exposure control
measures (e.g., expanded or transmission-based
                                                     efficient, and successful.                           plan if they understand its rationale. Clearly
precautions) might be necessary to prevent
                                                                                                          written policies, procedures and guidelines can
potential spread of certain diseases (e.g., TB,      Although the infection control coordinator           help ensure consistency, efficiency and effective
influenza and varicella) that are transmitted        remains responsible for overall management           coordination of activities. Personnel subject to
through airborne, droplet or contact transmission    of the program, creating and maintaining a           occupational exposure should receive infection
(e.g., sneezing, coughing and contact with skin).    safe work environment ultimately requires the        control training on initial assignment, when new
When acutely ill with these diseases, patients       commitment and accountability of all dental          tasks or procedures affect their occupational
do not usually seek routine dental outpatient        workers. This course is designed to provide          exposure, and at a minimum, annually.
care. Nonetheless, a general understanding of        guidance to workers for preventing disease           Education and training should be appropriate
precautions for diseases transmitted by all routes   transmission in dental health care settings, for     to the assigned duties of specific workers (e.g.,
is critical because:                                 promoting a safe working environment and for         techniques to prevent cross-contamination or
 Some dental health workers are hospital-           assisting dental practices in developing and         instrument sterilization). For dental workers
     based or work part-time in hospital settings.   implementing infection control programs. These       who perform tasks or procedures likely to result
 Patients infected with these diseases might        programs should be followed in addition to           in occupational exposure to infectious agents,
     seek urgent treatment at outpatient dental      practices and procedures for worker protection       training should include:
     offices.                                        required by the Occupational Safety and               A description of their exposure risks.
 Dental workers might become infected with          Health Administration’s (OSHA) standards              Review of prevention strategies and infection
     these diseases.                                 for occupational exposure to blood-borne                  control policies and procedures.
Necessary transmission-based precautions             pathogens, including instituting controls to          Discussion regarding how to manage work-
might include patient placement (e.g., isolation),   protect employees from exposure to blood or               related illness and injuries, including post-
adequate room ventilation, respiratory protection    other potentially infectious materials (OPIM),            exposure prophylaxis.
(e.g., N-95 masks) for workers, or postponement      and requiring implementation of a written             Review of work restrictions for an exposure
of nonemergency dental procedures.                   exposure-control plan, annual employee training,          or infection.
                                                     HBV vaccinations and post-exposure follow-
Dental health care personnel should be               up. Interpretations and enforcement procedures       Inclusion of dental workers with minimal
familiar also with the hierarchy of controls that    are available to help dental workers apply this      exposure risks (e.g., administrative employees) in
categorizes and prioritizes prevention strategies.   OSHA standard in practice. Also, manufacturers’      education and training programs might enhance
For blood-borne pathogens, engineering controls      Material Safety Data Sheets (MSDS) should            facilitywide understanding of infection control
that eliminate or isolate the hazard (e.g.,          be consulted regarding correct procedures for        principles and the importance of the program.
puncture-resistant sharps containers or needle       handling or working with hazardous chemicals.        Educational materials should be appropriate

Page 10                                                                                                                                            Elite CME
in content and vocabulary for each person’s           Exposure prevention and post-exposure                  Dental health workers should be familiar with
educational level, literacy and language, as well     management                                             the signs and symptoms of latex sensitivity. A
as be consistent with existing federal, state and     Avoiding exposure to blood and OPIM, as                physician should evaluate workers exhibiting
local regulations.                                    well as protection by immunization remain              symptoms of latex allergy, because further
                                                      primary strategies for reducing occupationally         exposure could result in a serious allergic
immunization programs
                                                      acquired infections, but occupational exposures        reaction. A diagnosis is made through medical
Dental workers are at risk for exposure to, and
possible infection with, infectious organisms.        can still occur. A combination of standard             history, physical examination and diagnostic
Immunizations substantially reduce both the           precautions, engineering, work practice and            tests. Procedures should be in place for
number of workers susceptible to these diseases       administrative controls is the best means to           minimizing latex-related health problems among
and the potential for disease transmission to other   minimize occupational exposures. Written               DHCP and patients while protecting them from
workers and patients. Thus, immunizations are an      policies and procedures to facilitate prompt           infectious materials. These procedures should
essential part of prevention and infection control    reporting, evaluation, counseling, treatment and       include:
programs for dental health care personnel, and a      medical follow-up of all occupational exposures         Reducing exposures to latex-containing
comprehensive immunization policy should be           should be available to all dental health care               materials by using appropriate work
implemented for all dental health care facilities.    personnel. Written policies and procedures                  practices.
The Advisory Committee on Immunization                should be consistent with federal, state and local      Training and educating dental workers on
Practices (ACIP) provides national guidelines         requirements addressing education and training,             monitoring symptoms.
for immunization of health care personnel, which      post-exposure management and exposure                   Substituting nonlatex products where
includes dental workers.                              reporting.                                                  appropriate.
Dental practice immunization policies should          Dental health personnel who have contact               Maintenance of records, data
incorporate current state and federal regulations     with patients can also be exposed to persons
                                                                                                             management and confidentiality
as well as recommendations from the U.S. Public       with infectious TB, and should have a baseline
                                                                                                             The health status of dental workers can be
Health Service and professional organizations.        tuberculin skin test (TST), preferably by using
                                                                                                             monitored by maintaining records of work-
                                                      a two-step test at the beginning of employment.
On the basis of documented health care-                                                                      related medical evaluations, screening tests,
                                                      Thus, if an unprotected occupational exposure
associated transmission, health care workers                                                                 immunizations, exposures and post-exposure
                                                      occurs, TST conversions can be distinguished
are considered to be at substantial risk for                                                                 management. Such records must be kept
                                                      from positive TST results caused by previous
acquiring or transmitting hepatitis B, influenza,                                                            in accordance with all applicable state and
                                                      exposures. The facility’s level of TB risk will
measles, mumps, rubella and varicella. All of                                                                federal laws. Examples of laws that might
                                                      determine the need for routine follow-up TSTs.
these diseases are vaccine-preventable. ACIP                                                                 apply include the Privacy Rule of the Health
recommends that all health care personnel             Medical conditions, work-related illness               Insurance Portability and Accountability Act
be vaccinated or have documented immunity             and work restrictions                                  (HIPAA) of 1996, 45 CFR 160 and 164, and the
to these diseases. ACIP does not recommend            Dental workers are responsible for monitoring          OSHA Occupational Exposure to Blood-borne
routine immunization of workers against               their own health status. Those who have acute          Pathogens; Final Rule 29 CFR 1910. 1030(h)
TB (i.e., inoculation with bacille Calmette-          or chronic medical conditions that render them         (1)(i–iv). The HIPAA Privacy Rule applies to
Guérin vaccine) or hepatitis A. No vaccine            susceptible to opportunistic infection should          covered entities, including certain defined health
exists for HCV. ACIP guidelines also provide          discuss with their personal physicians or other        providers, health care clearinghouses and health
recommendations regarding immunization of             qualified authority whether the condition might        plans. OSHA requires employers to ensure
workers with special conditions (e.g., pregnancy,     affect their ability to safely perform their duties.   that certain information contained in employee
HIV infection or diabetes).                           However, under certain circumstances, health           medical records is:
                                                      care facility managers might need to exclude            Kept confidential.
Immunization of workers before they are placed                                                                Not disclosed or reported without the
                                                      dental health personnel from work or patient
at risk for exposure remains the most efficient                                                                  employee’s express written consent to any
                                                      contact to prevent further transmission of
and effective use of vaccines in health care                                                                     person within or outside the workplace
settings. Some educational institutions and           infection. Decisions concerning work restrictions
                                                                                                                 except as required by the OSHA standard.
infection control programs provide immunization       are based on the mode of transmission and the
                                                                                                              Maintained by the employer for at least the
schedules for students and workers. OSHA              period of infectivity of the disease (Table 1).
                                                                                                                 duration of employment plus 30 years.
requires that employers make hepatitis B              Exclusion policies should:
vaccination available to all employees who             Be written.                                          Dental practices that coordinate their infection
have potential contact with blood or OPIM.             Include a statement of authority that defines        control program with off-site providers might
Employers are also required to follow CDC                 who can exclude dental workers (e.g.,              consult OSHA’s blood-borne pathogen standard
recommendations for vaccinations, evaluation              personal physicians).                              and employee access to medical and exposure
and follow-up procedures. Nonpatient care staff        Be clearly communicated through education            records standard, as well as other applicable
(e.g., administrative or housekeeping) might be           and training.                                      local, state and federal laws, to determine a
included, depending on their potential risk of                                                               location for storing health records.
                                                   Policies should also encourage workers to report
coming into contact with blood or OPIM.            illnesses or exposures without jeopardizing               Preventing transmission of blood-borne
Employers are also required to ensure that         wages, benefits or job status. With increasing            pathogens
employees who decline to accept hepatitis B        concerns regarding blood-borne pathogens and              Although transmission of blood-borne pathogens
vaccination sign an appropriate declination        introduction of universal precautions, use of             (e.g., HBV, HCV and HIV) in dental health
statement. Dental workers unable or unwilling to latex gloves among health care workers has                  care settings can have serious consequences,
be vaccinated as required or recommended should increased markedly. Increased use of these gloves            such transmission is rare. Exposure to infected
be educated regarding their exposure risks,        has been accompanied by increased reports of              blood can result in transmission from patient to
infection control policies and procedures for the  allergic reactions to natural rubber latex among          dental workers, from workers to patients, and
facility, and the management of work-related       workers and patients, as well as increased reports        from one patient to another. The opportunity for
illness and work restrictions (if appropriate) for of irritant and allergic contact dermatitis from          transmission is greatest from patients to dental
exposed or infected workers.                       frequent and repeated use of hand-hygiene                 workers, who frequently encounter patient blood
                                                   products, exposure to chemicals and glove use.            and blood-contaminated saliva during dental

Elite CME                                                                                                                                                Page 11
procedures. Since 1992, no HIV transmission            not efficient vehicles for transmission because      Only one case of patient-to-patient transmission
from dental care personnel to patients has been        they contain low quantities of infectious            of HBV in the dental setting has been
reported, and the last HBV transmission from           HBV, despite the presence of HBsAg. The              documented (CDC, unpublished data, 2003).
dental workers to patients was reported in 1987.       concentration of HBsAg in body fluids can be         In this case, appropriate office infection control
HCV transmission from workers to patients              100-1,000 times greater than the concentration of    procedures were being followed, and the exact
has not been reported. The majority of dental          infectious HBV particles.                            mechanism of transmission was undetermined.
care workers infected with a blood-borne virus         Although percutaneous injuries are among the         Because of the high risk of HBV infection to
do not pose a risk to patients because they do         most efficient modes of HBV transmission,            health care and dental workers who perform tasks
not perform activities meeting the necessary           these exposures probably account for only a          that might involve contact with blood, blood-
conditions for transmission. For workers to pose       minority of HBV infections among health care         contaminated body substances, other body fluids
a risk for blood-borne virus transmission to           workers. In multiple investigations of nosocomial    or sharps, such workers should be vaccinated.
patients, the worker must:                             hepatitis B outbreaks, the majority of infected      Vaccination can protect both dental care workers
 Be viremic, i.e., have infectious virus              health care workers could not recall an overt        and patients from HBV infection and, whenever
     circulating in the bloodstream.                   percutaneous injury, although in certain studies,    possible, should be completed when dentists or
 Be injured or have a condition (e.g., weeping        approximately one-third of infected workers          other dental staff are in training and before they
     dermatitis) that allows direct exposure to        recalled caring for a patient who was HBsAg-         have contact with blood.
     their blood or other infectious body fluids.      positive. In addition, HBV has been demonstrated
 Enable their blood or infectious body fluid                                                               Prevaccination serological testing for previous
                                                       to survive in dried blood at room temperature on
     to gain direct access to a patient’s wound,                                                            infection is not indicated, although it can be
                                                       environmental surfaces for one week. Thus, HBV
     traumatized tissue, mucous membranes                                                                   cost-effective where prevalence of infection
                                                       infections that occur in workers with no history
     or similar portal of entry. Although an                                                                is expected to be high in a group of potential
                                                       of nonoccupational exposure or occupational
     infected worker might be viremic, unless                                                               vacinees (e.g., persons who have emigrated
                                                       percutaneous injury might have resulted from
     the second and third conditions are also met,                                                          from areas with high rates of HBV infection).
                                                       direct or indirect blood or body fluid exposures
     transmission cannot occur.                                                                             Dental workers should be tested for anti-HBs
                                                       that inoculated HBV into cutaneous scratches,
                                                                                                            1-2 months after completion of the three-dose
The risk of occupational exposure to blood-borne       abrasions, burns, other lesions or on mucosal
                                                                                                            vaccination series. Those who do not develop an
viruses is largely determined by their prevalence      surfaces. The potential for HBV transmission
                                                                                                            adequate antibody response (i.e., anti-HBs less
in the patient population and the nature and           through contact with environmental surfaces
                                                                                                            than 10 mIU/mL) to the primary vaccine series
frequency of contact with blood and body fluids        has been demonstrated in investigations of
                                                                                                            should complete a second three-dose vaccine
through percutaneous or permucosal routes of           HBV outbreaks among patients and health care
                                                                                                            series or be evaluated to determine if they are
exposure. The risk of infection after exposure to      personnel in hemodialysis units.
                                                                                                            HBsAg-positive. Revaccinated persons should
a blood-borne virus is influenced by inoculum      Since the early 1980s, occupational infections           be retested for anti-HBs at the completion of the
size, route of exposure and susceptibility of the  among health workers have declined because               second vaccine series. Approximately half of
exposed health care personnel. The majority of     of vaccine use and adherence to universal                nonresponders to the primary series will respond
attention has been placed on the blood-borne       precautions. Among U. S. dentists, more than             to a second three-dose series. If no antibody
pathogens HBV, HCV and HIV, and these              90 percent have been vaccinated, and serologic           response occurs after the second series, testing
pathogens present different levels of risk to dental
                                                   evidence of past HBV infection decreased from            for HBsAg should be performed.
care workers.                                      prevaccine levels of 14 percent in 1972, to
                                                   approximately 9 percent in 1992. During 1993–            Persons who prove to be HBsAg-positive should
Hepatitis B virus                                                                                           be counseled regarding how to prevent HBV
HBV is a well-recognized occupational risk         2001, levels remained relatively unchanged.
                                                   Infection rates can be expected to decline               transmission to others and regarding the need for
for health care workers. HBV is transmitted                                                                 medical evaluation. Nonresponders to vaccination
by percutaneous or mucosal exposure to blood       further as vaccination rates remain high among
                                                   young dentists and as older dentists with lower          who are HBsAg-negative should be considered
or body fluids of a person with either acute or                                                             susceptible to HBV infection and should be
chronic HBV infection. Persons infected with       vaccination rates and higher rates of infection
                                                                                                            counseled regarding precautions to prevent
HBV can transmit the virus for as long as they are retire.                                                  HBV infection and the need to obtain HBIG
HBsAg-positive. The risk of HBV transmission       Although the potential for transmission of               prophylaxis for any known or probable parenteral
is highly related to the HBeAg status of           blood-borne infections from dental care workers          exposure to HBsAg-positive blood.
the source person. In studies of health care       to patients is considered limited, precise risks
personnel who sustained injuries from needles      have not been quantified by carefully designed           Vaccine-induced antibodies decline gradually
contaminated with blood containing HBV, the        epidemiologic studies. Reports published during          over time, and 60 percent of persons who initially
risk of developing clinical hepatitis if the blood 1970-1987 describe nine clusters in which                respond to vaccination will lose detectable
was positive for both HBsAg and HBeAg was          patients were thought to be infected with HBV            antibodies over 12 years. Even so, immunity
22 percent to 31 percent; the risk of developing   through treatment by an infected dental worker.          continues to prevent clinical disease or detectable
serologic evidence of HBV infection was 37–62      However, transmission of HBV from dentist to             viral infection. Booster doses of vaccine and
percent. By comparison, the risk of developing     patient has not been reported since 1987, possibly       periodic serologic testing to monitor antibody
clinical hepatitis from a needle contaminated with reflecting such factors as:                              concentrations after completion of the vaccine
HBsAg-positive, HBeAg-negative blood was            Adoption of universal precautions.                     series are not necessary for vaccine responders.
1-6 percent, and the risk of developing serologic   Routine glove use.                                     Hepatitis D virus
evidence of HBV infection, 23-37 percent.           Increased levels of immunity as a result               An estimated 4 percent of persons with acute
Blood contains the greatest proportion of HBV           of hepatitis B vaccination of dental care           HBV infection are also infected with hepatitis
infectious particle titers of all body fluids and       workers.                                            delta virus (HDV). Discovered in 1977, HDV
is the most critical vehicle of transmission in     Implementation of the 1991 OSHA blood-                 is a defective blood-borne virus requiring the
the health care setting. HBsAg is also found in         borne pathogen standard.                            presence of HBV to replicate. Patients co-
multiple other body fluids, including breast milk,  Incomplete ascertainment and reporting.                infected with HBV and HDV have substantially
bile, cerebrospinal fluid, feces, nasopharyngeal       Standard precautions are strategies used to reduce   higher mortality rates than those infected with
washings, saliva, semen, sweat and synovial            the risk of infection from exposure to blood,        HBV alone. Because HDV infection is dependent
fluid. However, the majority of body fluids are        all body fluids and secretions (except sweat),       on HBV for replication, immunization to prevent
                                                       nonintact skin and mucous membranes.
Page 12                                                                                                                                              Elite CME
HBV infection, through either pre- or post-           after an occupational exposure. Laboratory             finger guards while suturing) might also reduce
exposure prophylaxis, can also prevent HDV            studies have determined that if needles that pass      injuries during dental procedures.
infection.                                            through latex gloves are solid rather than hollow-
                                                                                                             Engineering controls are the primary method
                                                      bore, or are of small gauge (e.g., anesthetic
Hepatitis C virus                                                                                            to reduce exposures to blood and OPIM from
                                                      needles commonly used in dentistry), they
Hepatitis C virus appears not to be transmitted                                                              sharp instruments and needles. These controls
                                                      transfer less blood. In a retrospective case-control
efficiently through occupational exposures                                                                   are frequently technology-based and often
                                                      study of health care personnel, an increased risk
to blood. Follow-up studies of HCP exposed                                                                   incorporate safer designs of instruments and
                                                      for HIV infection was associated with exposure
to HCV-infected blood through percutaneous                                                                   devices (e.g., self-sheathing anesthetic needles
                                                      to a relatively large volume of blood, as indicated
or other sharps injuries have determined a                                                                   and dental units designed to shield burs in
                                                      by a deep injury with a device that was visibly
low incidence of seroconversion (mean: 1.8                                                                   handpieces) to reduce percutaneous injuries.
                                                      contaminated with the patient’s blood, or a
percent; range, 0 percent-7 percent). One study                                                              Work-practice controls establish practices to
                                                      procedure that involved a needle placed in a
determined transmission occurred from hollow-                                                                protect dental workers whose responsibilities
                                                      vein or artery. The risk was also increased if
bore needles but not other sharps. Although these                                                            include handling, using, assembling or processing
                                                      the exposure was to blood from patients with
studies have not documented seroconversion                                                                   sharp devices (e.g., needles, scalers, laboratory
                                                      terminal illnesses, possibly reflecting the higher
associated with mucous membrane or                                                                           utility knives, burs, explorers and endodontic
                                                      titer of HIV in late-stage AIDS.
nonintact skin exposure, at least two cases                                                                  files) or sharps disposal containers. Work-practice
of HCV transmission from a blood splash to            Exposure prevention methods                            controls can include removing burs before
the conjunctiva and one case of simultaneous          Avoiding occupational exposures to blood is the        disassembling the handpiece from the dental
transmission of HCV and HIV after nonintact           primary way to prevent transmission of HBV,            unit, restricting use of fingers in tissue retraction
skin exposure have been reported.                     HCV and HIV, to workers in health care settings.       or palpation during suturing and administration
                                                      Exposures occur through percutaneous injury            of anesthesia and minimizing potentially
Data are insufficient to estimate the occupational
                                                      (e.g., a needlestick or cut with a sharp object),      uncontrolled movements of such instruments as
risk of HCV infection among health care
                                                      as well as through contact between potentially         scalers or laboratory knives.
workers, but the majority of studies indicate the
                                                      infectious blood, tissues or other body fluids and
prevalence of HCV infection among dentists,                                                                  As indicated, needles are a substantial source
                                                      mucous membranes of the eye, nose, mouth or
surgeons and hospital-based workers is similar to                                                            of percutaneous injury in dental practice, and
                                                      nonintact skin (e.g., exposed skin that is chapped,
that among the general population, approximately                                                             engineering and work-practice controls for needle
                                                      abraded or shows signs of dermatitis).
1-2 percent. In a study that evaluated risk                                                                  handling are of particular importance. In 2001,
factors for infection, a history of unintentional     Observational studies and surveys indicate that        revisions to OSHA’s blood-borne pathogens
needlesticks was the only occupational risk factor    percutaneous injuries among general dentists           standard as mandated by the Needlestick Safety
independently associated with HCV infection. No       and oral surgeons occur less frequently than           and Prevention Act of 2000 became effective.
studies of transmission from HCV-infected dental      among general and orthopedic surgeons and              These revisions clarify the need for employers
workers to patients have been reported, and           have decreased in frequency since the mid-             to consider safer needle devices as they become
the risk for such transmission appears limited.       1980s. This decline has been attributed to safer       available and to involve employees directly
Multiple reports have been published describing       work practices, safer instrumentation or design,       responsible for patient care (e.g., dentists,
transmission from HCV-infected surgeons, which        and continued dental care workers education.           hygienists and dental assistants) in identifying
apparently occurred during performance of             Percutaneous injuries among DHCP usually:              and choosing such devices. Safer versions of
invasive procedures; the overall risk for infection    Occur outside the patient’s mouth, thereby           sharp devices used in hospital settings have
averaged 0.17 percent.                                    posing less risk for recontact with patient        become available (e.g., blunt suture needles,
                                                          tissues.                                           phlebotomy devices and butterfly needles),
Human immunodeficiency virus                           Involve limited amounts of blood.
In the United States, the risk of HIV transmission                                                           and their impact on reducing injuries has been
                                                       Are caused by burs, syringe needles,                 documented. Aspirating anesthetic syringes that
in dental settings is extremely low. As of                laboratory knives and other sharp
December 2001, a total of 57 cases of HIV                                                                    incorporate safety features have been developed
                                                          instruments.                                       for dental procedures, but the low injury rates
seroconversion had been documented among
health care workers, but none among dental care       Injuries among oral surgeons might occur more          in dentistry limit assessment of their effect on
workers, after occupational exposure to a known       frequently during fracture reductions using wires.     reducing injuries among dental care workers.
HIV-infected source. Transmission of HIV to six       Experience, as measured by years in practice,          Work-practice controls for needles and other
patients of a single dentist with AIDS has been       does not appear to affect the risk of injury among     sharps include placing used disposable syringes
reported, but the mode of transmission could not      general dentists or oral surgeons.                     and needles, scalpel blades and other sharp items
be determined. As of Sept. 30, 1993, CDC had          The majority of exposures in dentistry are             in appropriate puncture-resistant containers
information regarding test results of more than       preventable, and methods to reduce the                 located as close as feasible to where the items
22,000 patients of 63 HIV-infected health care        risk of blood contacts have included use of            were used. In addition, used needles should never
workers, including 33 dentists or dental students.    standard precautions, use of devices with              be recapped or otherwise manipulated by using
No additional cases of transmission were              features engineered to prevent sharp injuries          both hands or any other technique that involves
documented.                                           and modifications of work practices. These             directing the point of a needle toward any part
Prospective studies worldwide indicate the            approaches might have contributed to the               of the body. A one-handed scoop technique,
average risk of HIV infection after a single          decrease in percutaneous injuries among dentists       a mechanical device designed for holding the
percutaneous exposure to HIV-infected blood           during recent years. However, needlesticks and         needle cap to facilitate one-handed recapping,
is 0.3 percent (range: 0.2-0.5 percent). After an     other blood contacts continue to occur, which is       or an engineered sharps injury protection device
exposure of mucous membranes in the eye, nose         a concern because percutaneous injuries pose the       (e.g., needles with resheathing mechanisms)
or mouth, the risk is approximately 0.1 percent.      greatest risk of transmission.                         should be employed for recapping needles
The precise risk of transmission after skin         Standard precautions include use of personal             between uses and before disposal. Dental care
exposure remains unknown, but is believed to        protective equipment (e.g., gloves, masks,               workers should never bend or break needles
be even smaller than that for mucous membrane       protective eyewear or face shield, and gowns)            before disposal because this practice requires
exposure.                                           intended to prevent skin and mucous membrane             unnecessary manipulation. Before attempting to
                                                                                                             remove needles from nondisposable aspirating
Certain factors affect the risk of HIV transmission exposures. Other protective equipment (e.g.,             syringes, they should recap them to prevent

Elite CME                                                                                                                                                 Page 13
injuries. For procedures involving multiple           washed with soap and water; mucous membranes           other management of health care worker
injections with a single needle, the practitioner     should be flushed with water. No evidence              exposures to HBV, HCV or HIV. In 2001,
should recap the needle between injections by         exists that using antiseptics for wound care           these recommendations were updated and
using a one-handed technique or use a device          or expressing fluid by squeezing the wound             consolidated into one set of Public Health
with a needle-resheathing mechanism. Passing          further reduces the risk of blood-borne pathogen       Service guidelines. The new guidelines reflect
a syringe with an unsheathed needle should be         transmission; however, use of antiseptics is not       the availability of new anti-retroviral agents,
avoided because of the potential for injury.          contraindicated. The application of caustic agents     new information regarding the use and safety
                                                      (e.g., bleach) or the injection of antiseptics or      of HIV PEP, and considerations regarding
Additional information for developing a safety
                                                      disinfectants into the wound is not recommended.       employing HIV prophylaxis when resistance of
program and for identifying and evaluating safer
                                                      Exposed workers should immediately report the          the source patient’s virus to anti-retroviral agents
dental devices is available at:
                                                      exposure to the infection control coordinator          is known or suspected. In addition, the 2001
                                                      or other designated person, who should initiate        guidelines provide guidance to clinicians and
    infectioncontrol/ forms.htm (forms for
                                                      referral to the qualified health care professional     exposed workers regarding when to consider HIV
    screening and evaluating safer dental
                                                      and complete necessary reports.                        prophylaxis and recommendations for treatment
 http://www.cdc.gov/niosh/topics/bbp (state          Because multiple factors contribute to the risk of
    legislation on needlestick safety).               infection after an occupational exposure to blood,     Hand hygiene
                                                      the following information should be included           Hand hygiene (e.g., hand-washing, hand
Post-exposure management and                          in the exposure report, recorded in the exposed        antisepsis or surgical-hand antisepsis)
prophylaxis                                           person’s confidential medical record and provided      substantially reduces potential pathogens on the
Post-exposure management is an integral               to the qualified health care professional:             hands and is considered the single most critical
component of a complete program to prevent             Date and time of exposure.                           measure for reducing the risk of transmitting
infection after an occupational exposure to            Details of the procedure being performed,            organisms to patients and health care personnel.
blood. During dental procedures, saliva is                 including where and how the exposure              Hospital-based studies have demonstrated that
predictably contaminated with blood. Even                  occurred and whether the exposure involved        noncompliance with hand hygiene practices is
when blood is not visible, it can still be present         a sharp device, the type and brand of device,     associated with health care-associated infections
in limited quantities and therefore is considered          and how and when during its handling the          and the spread of multiresistant organisms.
a potentially infectious material by OSHA. A               exposure occurred.                                Noncompliance also has been a major contributor
qualified health care professional should evaluate     Details of the exposure, including its severity      to outbreaks. The prevalence of health care-
any occupational exposure incident to blood or             and the type and amount of fluid or material.     associated infections decreases as adherence
OPIM, including saliva, regardless of whether              Š For a percutaneous injury, severity might       of health care workers to recommended hand
blood is visible, in dental settings.                          be measured by the depth of the wound,        hygiene measures improves.
Dental practices and laboratories should establish             gauge of the needle and whether fluid
                                                                                                             The microbial flora of the skin, first described
written, comprehensive programs that include                   was injected.
                                                                                                             in 1938, consist of transient and resident
hepatitis B vaccination and post-exposure                  Š For a skin or mucous membrane
                                                                                                             microorganisms. Transient flora, which colonize
management protocols that:                                     exposure, the estimated volume of
                                                                                                             the superficial layers of the skin, are easier to
 Describe the types of contact with blood or                  material, duration of contact and the
                                                                                                             remove by routine hand-washing. They are often
    OPIM that can place dental care workers at                 condition of the skin (e.g., chapped,
                                                                                                             acquired by workers during direct contact with
    risk for infection.                                        abraded or intact) should be noted.
                                                                                                             patients or contaminated environmental surfaces;
 Describe procedures for promptly reporting               Š Details regarding whether the source
                                                                                                             these organisms are most frequently associated
    and evaluating such exposures.                             material was known to contain HIV or
                                                                                                             with health care-associated infections. Resident
 Identify a health care professional who is                   other blood-borne pathogens.
                                                                                                             flora attached to deeper layers of the skin are
    qualified to provide counseling and perform            Š If the source was infected with HIV, the
                                                                                                             more resistant to removal and less likely to be
    all medical evaluations and procedures in                  stage of disease, history of antiretroviral
                                                                                                             associated with such infections.
    accordance with current recommendations                    therapy and viral load, if known.
    of the U. S. Public Health Service (PHS),          Details regarding the exposed person (e.g.,          The preferred method for hand hygiene
    including prophylaxis with chemotherapeutic            hepatitis B vaccination and vaccine-response      depends on the type of procedure, the degree
    drugs when indicated.                                  status).                                          of contamination and the desired persistence
                                                       Details regarding counseling, post-exposure          of antimicrobial action on the skin. For routine
Dental workers, including students, who might              management and follow-up.                         dental examinations and nonsurgical procedures,
reasonably be considered at risk for occupational                                                            hand-washing and hand antisepsis is achieved
exposure to blood or OPIM should be taught            Each occupational exposure should be evaluated
                                                                                                             by using either a plain or antimicrobial soap
strategies to prevent contact with blood or OPIM      individually for its potential to transmit HBV,
                                                                                                             and water. If the hands are not visibly soiled, an
and the principles of post-exposure management,       HCV and HIV, based on the following:
                                                                                                             alcohol-based hand rub is adequate.
including prophylaxis options, as part of their job    The type and amount of body substance
orientation and training. Educational programs            involved.                                          The purpose of surgical hand antisepsis is to
for dental workers and students should emphasize       The type of exposure (e.g., percutaneous             eliminate transient flora and reduce resident
reporting all exposures to blood or OPIM as soon          injury, mucous membrane or nonintact skin          flora for the duration of a procedure to prevent
as possible, because certain interventions have to        exposure, or bites resulting in blood exposure     introduction of organisms in the operative
be initiated promptly to be effective.                    to either person involved).                        wound, if gloves become punctured or torn.
                                                       The infection status of the source.                  Skin bacteria can rapidly multiply under surgical
Policies should be consistent with the practices       The susceptibility of the exposed person.            gloves if hands are washed with soap that is not
and procedures for worker protection required                                                                antimicrobial. Thus, an antimicrobial soap or
by OSHA and with current Public Health Service        All of these factors should be considered in           alcohol hand rub with persistent activity should
recommendations for managing occupational             assessing the risk for infection and the need for      be used before surgical procedures.
exposures to blood.                                   further follow-up (e.g. post-exposure prophylaxis,
                                                      or PEP).                                           Agents used for surgical hand antisepsis should
After an occupational blood exposure, first aid                                                          substantially reduce microorganisms on intact
should be administered as necessary. Puncture         During 1990-1998, the Public Health                skin, contain a nonirritating antimicrobial
wounds and other injuries to the skin should be       Service published guidelines for PEP and
Page 14                                                                                                                                                Elite CME
preparation, have a broad spectrum of activity,       to cause skin irritation varies considerably, but      instruments (e.g., handpieces or ultrasonic
be fast-acting and have a persistent effect.          can be reduced by adding emollients. Lotions           scalers) and air-water syringes creates a visible
Persistence (i.e., extended antimicrobial             are often recommended to ease the dryness              spray that contains primarily large particle
activity that prevents or inhibits survival of        resulting from frequent hand-washing and to            droplets of water, saliva, blood, microorganisms
microorganisms after the product is applied) is       prevent dermatitis from glove use. However,            and other debris. This spatter travels only a
critical because microorganisms can colonize          petroleum-based lotion formulations can weaken         short distance and settles out quickly, landing
on hands in the moist environment underneath          latex gloves and increase permeability. For that       on the floor, nearby operatory surfaces, dental
gloves.                                               reason, lotions that contain petroleum or other        care workers or the patient. The spray also
                                                      oil emollients should only be used at the end of       might contain certain aerosols (i.e., particles of
Alcohol hand rubs are rapidly germicidal
                                                      the work day. Dental practitioners should obtain       respirable size, less than 10 μm). Aerosols can
when applied to the skin, but should include
                                                      information from lotion manufacturers regarding        remain airborne for extended periods and can be
such antiseptics as chlorhexidine, quaternary
                                                      interaction between lotions, gloves, dental            inhaled. However, they should not be confused
ammonium compounds, octenidine or triclosan
                                                      materials and antimicrobial products.                  with the large-particle spatter that makes up the
to achieve persistent activity. Factors that can
                                                                                                             bulk of the spray from handpieces and ultrasonic
influence the effectiveness of the surgical hand      Fingernails and artificial nails                       scalers. Appropriate work practices, including use
antisepsis in addition to the choice of antiseptic    Although the relationship between fingernail
                                                                                                             of dental dams and high-velocity air evacuation,
agent include duration and technique of               length and wound infection is unknown, keeping
                                                                                                             should minimize dissemination of droplets,
scrubbing, as well as condition of the hands, and     nails short is considered key because the majority
                                                                                                             spatter and aerosols.
techniques used for drying and gloving. CDC’s         of flora on the hands are found under and around
2002 guideline on hand hygiene in health care         the fingernails. Fingernails should be short           Protective clothing
settings provides more complete information.          enough to allow dental workers to thoroughly           Protective clothing and equipment (e.g., gowns,
                                                      clean underneath them and prevent glove tears.         lab coats, gloves, masks and protective eyewear
selection of antiseptic agents                                                                               or face shield) should be worn to prevent
                                                      Sharp nail edges or broken nails are also likely to
Selecting the most appropriate antiseptic
                                                      increase glove failure. Long artificial or natural     contamination of street clothing and to protect
agent for hand hygiene requires consideration
                                                      nails can make donning gloves more difficult and       the skin of dental workers from exposures to
of multiple factors. Essential performance
                                                      can cause gloves to tear more readily.                 blood and body substances. Uniforms/scrubs are
characteristics of a product (e.g., the spectrum
                                                                                                             not considered personal protective equipment
and persistence of activity and whether or not        Hand carriage of gram-negative organisms has
                                                                                                             when anticipating spatter of blood or body fluids.
the agent is fast acting) should be determined        been determined to be greater among wearers
                                                                                                             OSHA blood-borne pathogens standard requires
before selecting a product. Delivery system, cost     of artificial nails than among nonwearers, both
                                                                                                             sleeves to be long enough to protect the forearms
per use, reliable vendor support and supply are       before and after hand-washing. In addition,
                                                                                                             when the gown is worn as personal protective
also considerations. Because worker acceptance        artificial fingernails or extenders have been
                                                                                                             equipment (i.e., when spatter and spray of blood,
is a major factor regarding compliance with           epidemiologically implicated in multiple
                                                                                                             saliva or OPIM to the forearms is anticipated).
recommended hand hygiene protocols,                   outbreaks involving fungal and bacterial
                                                                                                             Dental personnel should change protective
considering their needs is critical and should        infections in hospital intensive-care units and
                                                                                                             clothing when it becomes visibly soiled and
include possible chemical allergies, skin integrity   operating rooms. Freshly applied nail polish on
                                                                                                             as soon as feasible if penetrated by blood or
after repeated use, compatibility with lotions        natural nails does not increase the microbial load
                                                                                                             other potentially infectious fluids. All protective
used and offensive agent ingredients (e.g., scent).   from periungual skin if fingernails are short;
                                                                                                             clothing should be removed before leaving the
Discussing specific preparations or ingredients       however, chipped nail polish can harbor added
                                                                                                             work area.
used for hand antisepsis is beyond the scope of       bacteria.
this report. Health care workers should choose                                                               gloves and gloving
from commercially available health care worker
                                                      Jewelry                                                DHCP wear gloves to prevent contamination of
                                                      Studies have demonstrated that skin underneath
hand washes when selecting agents for hand                                                                   their hands when touching mucous membranes,
                                                      rings is more heavily colonized than comparable
antisepsis or surgical hand antisepsis.                                                                      blood, saliva or OPIM, and also to reduce the
                                                      areas of skin on fingers without rings. In a study
                                                                                                             likelihood that microorganisms present on the
storage and dispensing of hand-care                   of intensive-care nurses, multivariable analysis
                                                                                                             workers’ hands will be transmitted to patients
products                                              determined rings were the only substantial risk
                                                                                                             during surgical or other patient-care procedures.
Hand-washing products, including plain (i.e.,         factor for carriage of gram-negative bacilli and
                                                                                                             Medical gloves, both patient examination and
non-antimicrobial) soap and antiseptic products,      Staphylococcus aureus, and the concentration of
                                                                                                             surgeon’s gloves, are manufactured as single-
can become contaminated or support the growth         organisms correlated with the number of rings
                                                                                                             use disposable items that should be used for
of microorganisms. Liquid products should be          worn. However, two other studies demonstrated
                                                                                                             only one patient, then discarded. Gloves should
stored in closed containers and dispensed from        that mean bacterial colony counts on hands
                                                                                                             be changed between patients and when torn or
either disposable containers or containers that       after hand-washing were similar among persons
are washed and dried thoroughly before refilling.     wearing rings and those not wearing rings.
Soap should not be added to a partially empty         Whether wearing rings increases the likelihood         Wearing gloves does not eliminate the need
dispenser, because this practice of topping off       of transmitting a pathogen is unknown; further         for hand-washing. Hand hygiene should be
might lead to bacterial contamination. Store and      studies are needed to establish whether rings          performed immediately before donning gloves.
dispense products according to manufacturers’         result in higher transmission of pathogens             Gloves can have small, unapparent defects or
directions.                                           in health care settings. However, rings and            can be torn during use, and hands can become
                                                      decorative nail jewelry can make donning gloves        contaminated during glove removal. These
Lotions                                               more difficult and cause gloves to tear more           circumstances increase the risk of operative
The primary defense against infection and             readily. Thus, jewelry should not interfere with       wound contamination and exposure of the
transmission of pathogens is healthy, unbroken        glove use (e.g., impair ability to wear the correct-   worker’s hands to microorganisms from patients.
skin. Frequent hand-washing with soaps and            sized glove or alter glove integrity).                 FDA regulates the medical glove industry, which
antiseptic agents can cause chronic irritant                                                                 includes gloves marketed as sterile surgeon’s
contact dermatitis among workers. Damage to           Personal protective equipment                          and sterile or nonsterile patient examination
the skin changes skin flora, resulting in more        PPE is designed to protect the skin and the            gloves. General-purpose utility gloves are also
frequent colonization by staphylococci and gram-      mucous membranes of the eyes, nose and mouth           used in dental health care settings but are not
negative bacteria. The potential of detergents        of dental care workers from exposure to blood          regulated by FDA because they are not promoted
                                                      or OPIM. Use of rotary dental and surgical
Elite CME                                                                                                                                                Page 15
for medical use. More rigorous standards are           in the dental practice setting (e.g., methacrylates   vials). Any latex-containing devices that cannot
applied to surgeon’s gloves than to examination        and glutaraldehyde). Allergic contact dermatitis      be removed from the treatment environment
gloves. FDA has identified acceptable quality          often manifests as a rash beginning hours after       should be adequately covered or isolated. Persons
levels (e.g., maximum defects allowed) for glove       contact and, similar to irritant dermatitis, is       might also be allergic to chemicals used in the
manufacturers, but even intact gloves eventually       usually confined to the area of contact.              manufacture of natural rubber latex and synthetic
fail with exposure to mechanical (e.g., sharps,                                                              rubber gloves, as well as metals, plastics or other
                                                       Latex allergy (type I hypersensitivity to latex
fingernails or jewelry) and chemical (e.g.,                                                                  materials used in dental care.
                                                       proteins) can be a more serious systemic allergic
dimethy-acrylates) hazards and over time. These
                                                       reaction, usually beginning within minutes            Taking thorough health histories for both patients
variables can be controlled, ultimately optimizing
                                                       of exposure, but sometimes occurring hours            and dental workers, followed by avoidance of
glove performance, by:
                                                       later and producing varied symptoms. More             contact with potential allergens, can minimize
 Maintaining short fingernails.
                                                       common reactions include runny nose, sneezing,        the possibility of adverse reactions. Certain
 Minimizing or eliminating hand jewelry.
                                                       itchy eyes, scratchy throat, hives and itchy,         common predisposing conditions for latex allergy
 Using engineering and work-practice controls
                                                       burning skin sensations. More severe symptoms         include previous history of allergies, a history of
     to avoid injuries with sharps.
                                                       include asthma marked by difficult breathing,         spina bifida, urogenital anomalies or allergies to
sterile surgeon’s gloves and double-                   coughing spells and wheezing; cardiovascular          avocados, kiwis, nuts or bananas. The following
gloving during oral surgical procedures                and gastrointestinal ailments; and in rare cases,     precautions should be considered to ensure safe
Certain limited studies have determined no             anaphylaxis and death. The American Dental            treatment for patients who have possible or
difference in postoperative infection rates after      Association (ADA) began investigating the             documented latex allergy:
routine tooth extractions when surgeons wore           prevalence of type I latex hypersensitivity among      Be aware that latent allergens in the ambient
either sterile or nonsterile gloves. However,          dental care personnel at the ADA annual meeting           air can cause respiratory or anaphylactic
wearing sterile surgeon’s gloves during surgical       in 1994. In 1994 and 1995, approximately 2,000            symptoms among persons with latex
procedures is supported by a strong theoretical        dentists, hygienists and assistants volunteered           hypersensitivity. Patients with latex allergy
rationale. Sterile gloves minimize transmission        for skin-prick testing. Data demonstrated that 6.2        can be scheduled for the first appointment
of microorganisms from the hands of surgical           percent of those tested were positive for type I          of the day to minimize their inadvertent
dental care personnel to patients and prevent          latex hypersensitivity. Data from the subsequent          exposure to airborne latex particles.
contamination of the hands of the workers with         five years of this ongoing cross-sectional study       Communicate with other dental workers
the patient’s blood and body fluids. In addition,      indicated a decline in prevalence from 8.5 percent        regarding patients with latex allergy (e.g., by
sterile surgeon’s gloves are more rigorously           to 4.3 percent. This downward trend is similar            oral instructions, written protocols and posted
regulated by FDA and therefore, might provide          to that reported by other studies and might be            signage) to prevent them from bringing latex-
an increased level of protection for the provider if   related to use of latex gloves with lower allergen        containing materials into the treatment area.
exposure to blood is likely.                           content.                                               Frequently clean all working areas
                                                                                                                 contaminated with latex powder or dust.
Although the effectiveness of wearing two pairs        Natural rubber latex proteins responsible for
                                                                                                              Have emergency treatment kits with latex-
of gloves in preventing disease transmission has       latex allergy are attached to glove powder.
                                                                                                                 free products available at all times.
not been demonstrated, the majority of studies         When powdered latex gloves are worn, more
                                                                                                              If latex-related complications occur during
among health care workers have demonstrated            latex protein reaches the skin. In addition,
                                                                                                                 or after a procedure, manage the reaction
a lower frequency of inner glove perforation           when powdered latex gloves are donned or
                                                                                                                 and seek emergency assistance as indicated.
and visible blood on the surgeon’s hands when          removed, latex protein/powder particles become
                                                                                                                 Follow current medical emergency response
double gloves are worn. In one study evaluating        aerosolized and can be inhaled, contacting
                                                                                                                 recommendations for management of
double gloves during oral surgical and dental          mucous membranes. As a result, allergic patients
hygiene procedures, the perforation of outer latex     and dental workers can experience cutaneous,
gloves was greater during longer procedures            respiratory and conjunctival symptoms related         sterilization and disinfection of patient-
(i.e., more than 45 minutes), with the highest         to latex protein exposure. Dental care workers        care items
rate (10 percent) of perforation occurring             can become sensitized to latex protein with           Patient-care items (dental instruments, devices
during oral surgery procedures. Based on these         repeated exposure. Work areas where only              and equipment) are categorized as critical,
studies, double-gloving might provide additional       powder-free, low-allergen latex gloves are used       semicritical or noncritical, depending on the
protection from occupational blood contact.            demonstrate low or undetectable amounts of latex      potential risk for infection associated with their
Double-gloving does not appear to substantially        allergy-causing proteins and fewer symptoms           intended use (Table 1). Critical items used to
reduce either manual dexterity or tactile              among workers related to natural rubber latex         penetrate soft tissue or bone have the greatest
sensitivity. Additional protection might also be       allergy. Because of the role of glove powder in       risk of transmitting infection and should be
provided by specialty products (e.g., orthopedic       exposure to latex protein, NIOSH recommends           sterilized by heat. Semicritical items touch
surgical gloves and glove liners).                     that if latex gloves are chosen, workers should       mucous membranes or nonintact skin and have a
                                                       be provided with reduced protein, powder-free         lower risk of transmission; because the majority
Contact dermatitis and latex                           gloves. Nonlatex (e.g., nitrile or vinyl) powder-     of semicritical items in dentistry are heat-tolerant,
hypersensitivity                                       free and low-protein gloves are also available.       they also should be sterilized by using heat. If
Occupationally related contact dermatitis can          Although rare, potentially life-threatening           a semicritical item is heat-sensitive, it should,
develop from frequent and repeated use of              anaphylactic reactions to latex can occur, and        at a minimum, be processed with high-level
hand hygiene products, exposure to chemicals,          dental practices should be appropriately equipped     disinfection.
and glove use. Contact dermatitis is classified        and have procedures in place to respond to such
as either irritant or allergic. Irritant contact       emergencies.                                          Noncritical patient-care items pose the least
dermatitis is common, nonallergic and develops                                                               risk of transmission of infection, contacting
                                                       Dental care personnel and dental patients with        only intact skin, which can serve as an effective
as dry, itchy, irritated areas on the skin around
                                                       latex allergy should not have direct contact with     barrier to microorganisms. In the majority of
the area of contact. By comparison, allergic
                                                       latex-containing materials and should be in a         cases, cleaning, or if visibly soiled, cleaning
contact dermatitis (type IV hypersensitivity) can
                                                       latex-safe environment with all latex-containing      followed by disinfection with an EPA-registered
result from exposure to accelerators and other
                                                       products removed from their vicinity. Dental          hospital disinfectant is adequate. When the
chemicals used in the manufacture of rubber
                                                       patients with histories of latex allergy can be at    item is visibly contaminated with blood or
gloves (e.g., natural rubber latex, nitrile and
                                                       risk from dental products (e.g., prophylaxis cups,    OPIM, an EPA-registered hospital disinfectant
neoprene), as well as from other chemicals found
                                                       rubber dams, orthodontic elastics and medication
Page 16                                                                                                                                                Elite CME
with a tuberculocidal claim (i.e., intermediate-      mucous membranes of the eyes, nose or mouth.             Compatibility with items to be cleaned.
level disinfectant) should be used. Cleaning or       Contaminated instruments should be handled               Occupational health and exposure risks.
disinfection of certain noncritical patient-care      carefully to prevent exposure to sharp instruments
                                                                                                            Use of automated cleaning equipment (e.g.,
items can be difficult or damage the surfaces;        that can cause a percutaneous injury. Instruments
                                                                                                            ultrasonic cleaner or washer-disinfector) does not
therefore, use of disposable barrier protection of    should be placed in an appropriate container at
                                                                                                            require presoaking or scrubbing of instruments
these surfaces might be a preferred alternative.      the point of use to prevent percutaneous injuries
                                                                                                            and can increase productivity, improve cleaning
FDA-cleared sterilant/high-level disinfectants        during transport to the instrument processing
                                                                                                            effectiveness and decrease worker exposure to
and EPA registered disinfectants must have            area.
                                                                                                            blood and body fluids. Thus, using automated
clear label claims for intended use, and              Instrument processing requires multiple steps to      equipment can be safer and more efficient than
manufacturer instructions for use must be             achieve sterilization or high-level disinfection.     manually cleaning contaminated instruments.
followed.                                             Sterilization is a complex process requiring
                                                                                                            If manual cleaning is not performed immediately,
                                                      specialized equipment, adequate space, qualified
   TABLE 1. Infection control categories of                                                                 placing instruments in a puncture-resistant
                                                      dental workers who are provided with ongoing
        patient-care instruments                                                                            container and soaking them with detergent, a
                                                      training, and regular monitoring for quality
                                                                                                            disinfectant/detergent or an enzymatic cleaner
 Category      Definition         Dental              assurance. Correct cleaning, packaging, sterilizer-
                                                                                                            will prevent drying of patient material and make
                                  instrument/         loading procedures, sterilization methods or high-
                                                                                                            cleaning easier and less time-consuming. Use of
                                  item                level disinfection methods should be followed to
                                                                                                            a liquid chemical sterilant/high-level disinfectant
 Critical      Penetrates         Surgical            ensure that an instrument is adequately processed
                                                                                                            (e.g., glutaraldehyde) as a holding solution is not
               soft tissue,       instruments,        and safe for reuse on patients.
               contacts bone,     periodontal         instrument processing area
               enters into or     scalers,                                                                  Using work-practice controls (e.g., a long-
                                                      Dental workers should process all instruments         handled brush) to keep the scrubbing hand away
               contacts the       scalpel blades,     in a designated central processing area to more
               bloodstream or     surgical dental                                                           from sharp instruments is recommended. To
                                                      easily control quality and ensure safety. The         avoid injury from sharp instruments, workers
               other normally     burs.               central processing area should be divided into
               sterile tissue.                                                                              should wear puncture-resistant, heavy-duty
                                                      sections for:                                         utility gloves when handling or manually
 Semi-         Contacts           Dental mouth         Receiving, cleaning and decontamination.            cleaning contaminated instruments and devices.
 critical      mucous             mirror,              Preparation and packaging.                          Employees should not reach into trays or
               membranes          amalgam              Sterilization.                                      containers holding sharp instruments that cannot
               or nonintact       condenser,           Storage.                                            be seen (e.g., sinks filled with soapy water in
               skin; will not     reusable                                                                  which sharp instruments have been placed).
                                                      Ideally, walls or partitions should separate the
               penetrate soft     dental                                                                    Work-practice controls should include use of
                                                      sections to control traffic flow and contain
               tissue, contact    impression                                                                a strainer-type basket to hold instruments and
                                                      contaminants generated during processing. When
               bone, enter into   trays, dental                                                             forceps to remove the items. Because splashing
                                                      physical separation of these sections cannot be
               or contact the     handpieces*.                                                              is likely to occur, a mask, protective eyewear or
                                                      achieved, adequate spatial separation might be
               bloodstream or                                                                               face shield, and gown or jacket should be worn.
                                                      satisfactory if the dental workers who process
               other normally
                                                      instruments are trained in work practices to
               sterile tissue.                                                                              Preparation and packaging
                                                      prevent contamination of clean areas. Space
 Non-          Contacts intact    Radiograph                                                                In another section of the processing area, cleaned
                                                      should be adequate for the volume of work
 critical      skin.              head/cone,                                                                instruments and other dental supplies should
                                                      anticipated and the items to be stored.
                                  blood pressure                                                            be inspected, assembled into sets or trays, and
                                  cuff, facebow,      Receiving, cleaning and decontamination               wrapped, packaged or placed into container
                                  pulse oximeter      Reusable instruments, supplies and equipment          systems for sterilization. Hinged instruments
                                                      should be received, sorted, cleaned and               should be processed open and unlocked. An
 * Although dental handpieces are considered                                                                internal chemical indicator should be placed in
                                                      decontaminated in one section of the processing
 a semicritical item, they should always be                                                                 every package. In addition, an external chemical
                                                      area. Cleaning should precede all disinfection
 heat-sterilized between uses and not high-                                                                 indicator (e.g., chemical indicator tape) should be
                                                      and sterilization processes; it should involve
 level disinfected. See Dental handpieces and                                                               used when the internal indicator cannot be seen
                                                      removal of debris, as well as organic and
 other devices attached to air or waterlines for                                                            from outside the package. For unwrapped loads,
                                                      inorganic contamination. Removal of debris and
 detailed information.                                                                                      at a minimum, an internal chemical indicator
                                                      contamination is achieved either by scrubbing
Three levels of disinfection, high, intermediate      with a surfactant, detergent and water, or by         should be placed in the tray or cassette with items
and low, are used for patient-care devices            an automated process (e.g., ultrasonic cleaner        to be sterilized (see Sterilization of unwrapped
that do not require sterility; and two levels,        or washer-disinfector) using chemical agents.         instruments). Dental practices should refer to
intermediate and low, for environmental               If visible debris, whether inorganic or organic       the manufacturer’s instructions regarding use
surfaces. The intended use of the patient-care        matter, is not removed, it will interfere with        and correct placement of chemical indicators
item should determine the recommended level           microbial inactivation and can compromise             (see Sterilization monitoring). Critical and
of disinfection. Dental practices should follow       the disinfection or sterilization process. After      semicritical instruments that will be stored should
the product manufacturer’s directions regarding       cleaning, instruments should be rinsed with           be wrapped or placed in containers (e.g., cassettes
concentrations and exposure time for disinfectant     water to remove chemical or detergent residue.        or organizing trays) designed to maintain sterility
activity relative to the surface to be disinfected.   Splashing should be minimized during cleaning         during storage.
                                                      and rinsing. Before final disinfection or             Packaging materials (e.g., wraps or container
Transporting and processing                           sterilization, instruments should be handled as
contaminated critical and semi-critical                                                                     systems) allow penetration of the sterilization
                                                      though contaminated.                                  agent and maintain sterility of the processed
patient-care items
                                                      Considerations in selecting cleaning methods and      item after sterilization. Materials for maintaining
Dental workers can be exposed to
                                                      equipment include:                                    sterility of instruments during transport and
microorganisms on contaminated instruments
                                                       Efficacy of the method, process and                 storage include wrapped perforated instrument
and devices through percutaneous injury, contact
                                                          equipment.                                        cassettes, peel pouches of plastic or paper and
with nonintact skin on the hands or contact with
Elite CME                                                                                                                                               Page 17
sterilization wraps (woven and nonwoven).              Unsaturated air is forced out of the chamber           include a drying phase at the end to produce a
Packaging materials should be designed for the         through a vent in the chamber wall. Trapping of        dry instrument with much of the heat dissipated.
type of sterilization process being used.              air is a concern when using saturated steam under      If the drying phase requirements are unclear,
                                                       gravity displacement; errors in packaging items        the operation manual or manufacturer of the
sterilization                                          or overloading the sterilizer chamber can result in    sterilizer should be consulted. If the unwrapped
The sterilization section of the processing area
                                                       cool air pockets and items not being sterilized.       sterilization cycle in a steam sterilizer does not
should include the sterilizers and related supplies,
                                                                                                              include a drying phase or has only a minimal
with adequate space for loading, unloading and         Prevacuum sterilizers are fitted with a pump to
                                                                                                              drying phase, items retrieved from the sterilizer
cool down. The area can also include incubators        create a vacuum in the chamber and ensure air
                                                                                                              will be hot and wet, making aseptic transport to
for analyzing spore tests and enclosed storage         removal from the sterilizing chamber before the
                                                                                                              the point of use more difficult. For dry-heat and
for sterile items and disposable (single-use)          chamber is pressurized with steam. Relative to
                                                                                                              chemical-vapor sterilizers, a drying phase is not
items. Manufacturer and local building code            gravity displacement, this procedure allows faster
specifications will determine placement and room       and more positive steam penetration throughout
ventilation requirements.                              the entire load. Prevacuum sterilizers should          Unwrapped sterilization should be used only
                                                       be tested periodically for adequate air removal,       under certain conditions:
Sterilization procedures – Heat-tolerant dental
                                                       as recommended by the manufacturer. Air not             Thorough cleaning and drying of instruments
instruments usually are sterilized by:
                                                       removed from the chamber will interfere with              precedes the unwrapped sterilization cycle.
 Steam under pressure (autoclaving).
                                                       steam contact. If a sterilizer fails the air removal    Mechanical monitors are checked and
 Dry heat.
                                                       test, it should not be used until inspected by            chemical indicators used for each cycle.
 Unsaturated chemical vapor.
                                                       sterilizer maintenance personnel and it passes the      Care is taken to avoid thermal injury to dental
All sterilization should be performed by using         test. Manufacturer’s instructions, with specific          care personnel or patients.
medical sterilization equipment cleared by FDA.        details regarding operation and user maintenance        Items are transported aseptically to the point
The sterilization times, temperatures and other        information, should be followed.                          of use to maintain sterility.
operating parameters recommended by the
                                                       Unsaturated chemical-vapor sterilization –             Because all implantable devices should be
manufacturer of the equipment used, as well as
                                                       Unsaturated chemical-vapor sterilization involves      quarantined after sterilization until the results
instructions for correct use of containers, wraps
                                                       heating a chemical solution of primarily alcohol       of biological monitoring are known, unwrapped
and chemical or biological indicators, should
                                                       with 0.23 percent formaldehyde in a closed             or flash sterilization of implantable items is not
always be followed.
                                                       pressurized chamber. Unsaturated chemical vapor        recommended.
Items to be sterilized should be arranged to           sterilization of carbon steel instruments (e.g.,
                                                                                                              Critical instruments sterilized unwrapped should
permit free circulation of the sterilizing agent       dental burs) causes less corrosion than steam
                                                                                                              be transferred immediately by using aseptic
(e.g., steam, chemical vapor or dry heat);             sterilization because of the low level of water
                                                                                                              technique, from the sterilizer to the actual point
manufacturer’s instructions for loading the            present during the cycle. Instruments should be
                                                                                                              of use. Critical instruments should not be stored
sterilizer should be followed. Instrument packs        dry before sterilizing. State and local authorities
                                                                                                              unwrapped. Semicritical instruments that are
should be allowed to dry inside the sterilizer         should be consulted for hazardous waste disposal
                                                                                                              sterilized unwrapped on a tray or in a container
chamber before removing and handling. Packs            requirements for the sterilizing solution.
                                                                                                              system should be used immediately or within a
should not be touched until they are cool and
                                                       Dry-heat sterilization – Dry heat is used to           short time. When sterile items are open to the
dry because hot packs act as wicks, absorbing
                                                       sterilize materials that might be damaged by           air, they will eventually become contaminated.
moisture, and hence, bacteria from hands.
                                                       moist heat (e.g., burs and certain orthodontic         Storage, even temporary, of unwrapped
The ability of equipment to attain physical
                                                       instruments). Although dry heat has the                semicritical instruments is discouraged because
parameters required to achieve sterilization
                                                       advantages of low operating cost and being             it permits exposure to dust, airborne organisms
should be monitored by mechanical, chemical
                                                       noncorrosive, it is a prolonged process and the        and other unnecessary contamination before use
and biological indicators. Sterilizers vary in
                                                       high temperatures required are not suitable for        on a patient. A carefully written protocol for
their types of indicators and their ability to
                                                       certain patient-care items and devices. Dry-heat       minimizing the risk of contaminating unwrapped
provide readings on the mechanical or physical
                                                       sterilizers used in dentistry include static-air and   instruments should be prepared and followed.
parameters of the sterilization process (e.g., time,
                                                       forced-air types:
temperature and pressure). Consult with the                                                                   Other sterilization methods – Heat-sensitive
                                                        The static-air type is commonly called an
sterilizer manufacturer regarding selection and                                                               critical and semicritical instruments and
                                                            oven-type sterilizer. Heating coils in the
use of indicators.                                                                                            devices can be sterilized by immersing them in
                                                            bottom or sides of the unit cause hot air
                                                                                                              liquid chemical germicides registered by FDA
Steam sterilization – Among sterilization                   to rise inside the chamber through natural
                                                                                                              as sterilants. When using a liquid chemical
methods, steam sterilization, which is dependable           convection.
                                                                                                              germicide for sterilization, certain post-
and economical, is the most widely used for             The forced-air type is also known as a
                                                                                                              sterilization procedures are essential. Items need
wrapped and unwrapped critical and semicritical             rapid heat-transfer sterilizer. Heated air is
                                                                                                              to be:
items that are not sensitive to heat and moisture.          circulated throughout the chamber at a high
                                                                                                               Rinsed with sterile water after removal to
Steam sterilization requires exposure of each item          velocity, permitting more rapid transfer
                                                                                                                   remove toxic or irritating residues.
to direct steam contact at a required temperature           of energy from the air to the instruments,
                                                                                                               Handled using sterile gloves and dried with
and pressure for a specified time needed to                 thereby reducing the time needed for
                                                                                                                   sterile towels.
kill microorganisms. Two basic types of steam               sterilization.
                                                                                                               Delivered to the point of use in an aseptic
sterilizers are the gravity displacement and the
                                                       Sterilization of unwrapped instruments                      manner.
high-speed prevacuum sterilizer.
                                                       – An unwrapped cycle (sometimes called
                                                                                                              If an instrument is stored before use, the
The majority of tabletop sterilizers used in           flash sterilization) is a method for sterilizing
                                                                                                              instrument should not be considered sterile and
a dental practice are gravity displacement             unwrapped patient-care items for immediate use.
                                                                                                              should be sterilized again just before use. In
sterilizers, although prevacuum sterilizers are        The time required for unwrapped sterilization
                                                                                                              addition, the sterilization process with liquid
becoming more widely available. In gravity             cycles depends on the type of sterilizer and
                                                                                                              chemical sterilants cannot be verified with
displacement sterilizers, steam is admitted            the type of item (i.e., porous or nonporous) to
                                                                                                              biological indicators.
through steam lines, a steam generator or self-        be sterilized. The unwrapped cycle in tabletop
generation of steam within the chamber.                sterilizers is preprogrammed by the manufacturer       Because of these limitations and because liquid
                                                       to a specific time and temperature setting and can     chemical sterilants can require approximately 12

Page 18                                                                                                                                                 Elite CME
hours of complete immersion, they are almost          mechanical, chemical and biological. These             BI results are known. However, in an emergency,
never used to sterilize instruments. Rather,          parameters evaluate both the sterilizing               placing implantable items in quarantine until
these chemicals are more often used for high-         conditions and the procedure’s effectiveness.          spore tests are known to be negative might be
level disinfection. Shorter immersion times                                                                  impossible.
                                                      Mechanical techniques for monitoring
(12-90 minutes) are used to achieve high-level
                                                      sterilization include assessing cycle time,            Manufacturer’s directions should determine the
disinfection of semicritical instruments or items.
                                                      temperature and pressure by observing the              placement and location of BI in the sterilizer. A
These powerful, sporicidal chemicals (e.g.,
                                                      gauges or displays on the sterilizer and noting        control BI, from the same lot as the test indicator
glutaraldehyde, peracetic acid and hydrogen
                                                      these parameters for each load. Some tabletop          and not processed through the sterilizer, should
peroxide) are highly toxic. Manufacturer
                                                      sterilizers have recording devices that print out      be incubated with the test BI; the control BI
instructions (e.g., regarding dilution, immersion
                                                      these parameters. Correct readings do not ensure       should yield positive results for bacterial growth.
time and temperature) and safety precautions for
                                                      sterilization, but incorrect readings can be the
using chemical sterilants/high-level disinfectants                                                           In-office biological monitoring is available; mail-
                                                      first indication of a problem with the sterilization
must be followed precisely.                                                                                  in sterilization monitoring services (e.g., from
                                                                                                             private companies or dental schools) can also be
These chemicals should not be used for
                                                     Chemical indicators, internal and external,             used to test both the BI and the control. Although
applications other than those indicated in their
                                                     use sensitive chemicals to assess physical              some dental care personnel have expressed
label instructions. Misapplications include use
                                                     conditions (e.g., time and temperature) during          concern that delays caused by mailing specimens
as an environmental surface disinfectant or
                                                     the sterilization process. Although chemical            might cause false negatives, studies have
instrument-holding solution.
                                                     indicators do not prove sterilization has been          determined that mail delays have no substantial
When using appropriate precautions (e.g., closed achieved, they allow detection of certain                   effect on final test results.
containers to limit vapor release, chemically        equipment malfunctions, and they can help
                                                                                                             Procedures to follow in the event of a positive
resistant gloves and aprons, goggles and face        identify procedural errors. External indicators
                                                                                                             spore test have been developed. If the mechanical
shields), glutaraldehyde-based products can be       applied to the outside of a package (e.g., chemical
                                                                                                             (e.g., time, temperature and pressure) and
used without tissue irritation or adverse health     indicator tape or special markings) change color
                                                                                                             chemical (i.e., internal or external) indicators
effects. However, dermatologic, eye irritation,      rapidly when a specific parameter is reached, and
                                                                                                             demonstrate that the sterilizer is functioning
respiratory effects and skin sensitization have      they verify that the package has been exposed
                                                                                                             correctly, a single positive spore test probably
been reported. Because of their lack of chemical     to the sterilization process. Internal chemical
                                                                                                             does not indicate sterilizer malfunction. Items
resistance to glutaraldehydes, medical gloves        indicators should be used inside each package
                                                                                                             other than implantable devices do not necessarily
are not an effective barrier. Other factors might    to ensure the sterilizing agent has penetrated
                                                                                                             need to be recalled; however, the spore test
apply (e.g., room exhaust ventilation or 10 air      the packaging material and actually reached
                                                                                                             should be repeated immediately after correctly
exchanges/hour) to ensure workers’ safety. For all the instruments inside. A single-parameter
                                                                                                             loading the sterilizer and using the same cycle
of these reasons, using heat-sensitive semicritical internal chemical indicator provides information
                                                                                                             that produced the failure. The sterilizer should be
items that must be processed with liquid chemical regarding only one sterilization parameter (e.g.,
                                                                                                             removed from service, and all records reviewed
germicides is discouraged; heat-tolerant or          time or temperature). Multiparameter internal
                                                                                                             of chemical and mechanical monitoring since the
disposable alternatives are available for the        chemical indicators are designed to react to more
                                                                                                             last negative BI test.
majority of such items.                              than two parameters (e.g., time and temperature;
                                                     or time, temperature and the presence of steam)         Also, sterilizer operating procedures should be
Low-temperature sterilization with ethylene oxide
                                                     and can provide a more reliable indication              reviewed, including packaging, loading and
gas (ETO) has been used extensively in larger
                                                     that sterilization conditions have been met.            spore testing, with all persons who work with
health care facilities. Its primary advantage is the
                                                     Multiparameter internal indicators are available        the sterilizer to determine whether operator
ability to sterilize heat- and moisture-sensitive
                                                     only for steam sterilizers (i.e., autoclaves).          error could be responsible. Overloading, failure
patient-care items with reduced deleterious
                                                                                                             to provide adequate package separation and
effects. However, extended sterilization times       Because chemical indicator test results are
                                                                                                             incorrect or excessive packaging material are all
of 10-48 hours and potential hazards to patients     received when the sterilization cycle is complete,
                                                                                                             common reasons for a positive BI in the absence
and workers requiring stringent health and safety they can provide an early indication of a problem
                                                                                                             of mechanical failure of the sterilizer unit. A
requirements make this method impractical for        and where in the process the problem might exist.
                                                                                                             second monitored sterilizer in the office can be
private-practice settings. Handpieces cannot be      If either mechanical indicators or internal or
                                                                                                             used, or a loaner from a sales or repair company
effectively sterilized with this method because of external chemical indicators indicate inadequate
                                                                                                             obtained, to minimize office disruption while
decreased penetration of ETO gas flow through a processing, items in the load should not be used
                                                                                                             waiting for the repeat BI.
small lumen.                                         until reprocessed.
                                                                                                             If the repeat test is negative and chemical and
Other types of low-temperature sterilization (e.g.,   Biological indicators (BIs) (i.e., spore tests)
                                                                                                             mechanical monitoring indicates adequate
hydrogen peroxide gas plasma) exist but are not       are the most accepted method for monitoring
                                                                                                             processing, the sterilizer can be put back into
yet practical for dental offices. Bead sterilizers    the sterilization process because they assess
                                                                                                             service. If the repeat BI test is positive, and
have been used in dentistry to sterilize small        it directly by killing known highly resistant
                                                                                                             packaging, loading and operating procedures
metallic instruments (e.g., endodontic files).        microorganisms (e.g., Geobacillus or Bacillus
                                                                                                             have been confirmed as performing correctly,
FDA has determined that a risk of infection           species), rather than merely testing the
                                                                                                             the sterilizer should remain out of service until
exists with these devices because of their            physical and chemical conditions necessary for
                                                                                                             it has been inspected, repaired and rechallenged
potential failure to sterilize dental instruments     sterilization. Because spores used in BIs are
                                                                                                             with BI tests in three consecutive empty chamber
and has required their commercial distribution        more resistant and present in greater numbers
                                                                                                             sterilization cycles. When possible, items from
cease unless the manufacturer files a premarket       than the common microbial contaminants found
                                                                                                             suspect loads dating back to the last negative BI
approval application. If a bead sterilizer is         on patient-care equipment, an inactivated BI
                                                                                                             should be recalled, rewrapped and resterilized.
employed, DHCP assume the risk of employing           indicates other potential pathogens in the load
a dental device FDA has deemed neither safe nor       have been killed.                                      A more conservative approach has been
effective.                                                                                                   recommended in which any positive spore test
                                                      Correct functioning of sterilization cycles should
                                                                                                             is assumed to represent sterilizer malfunction
Sterilization monitoring – Monitoring of              be verified for each sterilizer by the periodic use
                                                                                                             and requires that all materials processed in that
sterilization procedures should include a             (at least weekly) of BIs. Every load containing
                                                                                                             sterilizer, dating from the sterilization cycle
combination of process parameters, including          implantable devices should be monitored with
                                                                                                             having the last negative biologic indicator to
                                                      such indicators, and the items quarantined until
Elite CME                                                                                                                                                Page 19
the next cycle indicating satisfactory biologic         although they have not been associated directly        that are difficult to clean. Barriers include clear
indicator results, should be considered nonsterile      with transmission of infection to either dental        plastic wrap, bags, sheets, tubing and plastic-
and retrieved, if possible, and reprocessed or held     workers or patients. Transfer of microorganisms        backed paper or other materials impervious to
in quarantine until the results of the repeat BI are    from contaminated environmental surfaces to            moisture. Because such coverings can become
known. This approach is considered conservative         patients occurs primarily through dental care          contaminated, they should be removed and
because the margin of safety in steam sterilization     personnel hand contact. When these surfaces are        discarded between patients while dental workers
is sufficient enough that infection risk associated     touched, microbial agents can be transferred to        are still gloved. After removing the barrier,
with items in a load indicating spore growth is         instruments, other environmental surfaces or to        examine the surface to make sure it did not
minimal, particularly if the item was properly          the nose, mouth or eyes of workers or patients.        become soiled inadvertently. The surface needs to
cleaned and the temperature was achieved (e.g.,         Although hand hygiene is key to minimizing             be cleaned and disinfected only if contamination
as demonstrated by acceptable chemical indicator        this transferal, barrier protection or cleaning        is evident. Otherwise, after removing gloves and
or temperature chart). Published studies are not        and disinfecting of environmental surfaces also        performing hand hygiene, dental workers should
available that document disease transmission            protects against health care-associated infections.    place clean barriers on these surfaces before the
through a nonretrieved surgical instrument              Environmental surfaces can be divided into             next patient. If barriers are not used, surfaces
after a steam sterilization cycle with a positive       clinical contact surfaces and housekeeping             should be cleaned and disinfected between
biological indicator. This more conservative            surfaces. Because housekeeping surfaces (e.g.,         patients by using an EPA-registered hospital
approach should always be used for sterilization        floors, walls and sinks) have limited risk of          disinfectant with an HIV, HBV claim (i.e., low-
methods other than steam (e.g., dry heat,               disease transmission, they can be decontaminated       level disinfectant) or a tuberculocidal claim (i.e.,
unsaturated chemical vapor, ETO or hydrogen             with less rigorous methods than those used on          intermediate-level disinfectant). Intermediate-
peroxide gas plasma).                                   dental patient-care items and clinical contact         level disinfectant should be used when the
                                                        surfaces. Strategies for cleaning and disinfecting     surface is visibly contaminated with blood or
Results of biological monitoring should be
                                                        surfaces in patient-care areas should consider the     OPIM. Also, general cleaning and disinfection
recorded and sterilization monitoring records
                                                        following:                                             are recommended for clinical contact surfaces,
(i.e., mechanical, chemical and biological)
                                                         Potential for direct patient contact.                dental unit surfaces and countertops at the end of
retained long enough to comply with state and
                                                         Degree and frequency of hand contact.                daily work activities and are required if surfaces
local regulations. Such records are a component
                                                         Potential contamination of the surface with          have become contaminated since their last
of an overall dental infection control program
                                                            body substances or environmental sources of        cleaning. To facilitate daily cleaning, treatment
(See program evaluation).
                                                            microorganisms (e.g., soil, dust or water).        areas should be kept free of unnecessary
storage of sterilized items and clean                                                                          equipment and supplies.
dental supplies                                         Cleaning is the necessary first step of any
                                                        disinfection process. Cleaning is a form of            Manufacturers of dental devices and equipment
The storage area should contain enclosed storage                                                               should provide information regarding
for sterile items and disposable (single-use)           decontamination that renders the environmental
                                                        surface safe by removing organic matter, salts and     material compatibility with liquid chemical
items. Storage practices for wrapped sterilized                                                                germicides, whether equipment can be safely
instruments can be either date- or event-related.       visible soils, all of which interfere with microbial
                                                        inactivation. The physical action of scrubbing         immersed for cleaning, and how it should be
Packages containing sterile supplies should be                                                                 decontaminated if service is required. Because
inspected before use to verify barrier integrity        with detergents and surfactants and rinsing
                                                        with water removes substantial numbers of              of the risks associated with exposure to chemical
and dryness.                                                                                                   disinfectants and contaminated surfaces, dental
                                                        microorganisms. If a surface is not cleaned first,
Although some health care facilities continue           the success of the disinfection process can be         workers who perform environmental cleaning
to date every sterilized package and use shelf-         compromised. Removal of all visible blood and          and disinfection should wear gloves and other
life practices, other facilities have switched          inorganic and organic matter can be as critical as     protective equipment to prevent occupational
to event-related practices. This approach               the germicidal activity of the disinfecting agent.     exposure to infectious agents and hazardous
recognizes that the product should remain sterile       When a surface cannot be cleaned adequately, it        chemicals. Chemical- and puncture-resistant
indefinitely unless an event causes it to become        should be protected with barriers.                     utility gloves offer more protection than patient
contaminated (e.g., torn or wet packaging). Even                                                               examination gloves when using hazardous
for event-related packaging, minimally, the date        Clinical contact surfaces                              chemicals.
of sterilization should be placed on the package,       Clinical contact surfaces can be directly
and if multiple sterilizers are used in the facility,   contaminated from patient materials by direct          Housekeeping surfaces
the sterilizer used should be indicated on the          spray or spatter generated either during dental        Evidence does not support that housekeeping
outside of the packaging material to facilitate         procedures or by contact with dental care              surfaces (e.g., floors, walls and sinks) pose a
the retrieval of processed items in the event of a      personnel’s gloved hands. These surfaces can           risk for disease transmission in dental health
sterilization failure. If packaging is compromised,     subsequently contaminate other instruments,            care settings. Actual physical removal of
the instruments should be recleaned, packaged in        devices, hands or gloves. Examples of such             microorganisms and soil by wiping or scrubbing
new wrap and sterilized again.                          surfaces include:                                      is probably as critical, if not more so, than any
                                                         Light handles.                                       antimicrobial effect provided by the agent used.
Clean supplies and instruments should be stored                                                                The majority of housekeeping surfaces need to
in closed or covered cabinets, if possible. Dental       Switches.
                                                         Dental radiograph equipment.                         be cleaned only with a detergent and water or an
supplies and instruments should not be stored                                                                  EPA-registered hospital disinfectant/detergent,
under sinks or in other locations where they             Dental chair-side computers.
                                                         Reusable containers of dental materials.             depending on the nature of the surface and the
might become wet.                                                                                              type and degree of contamination. Schedules
                                                         Drawer handles.
Environmental infection control                          Faucet handles.                                      and methods vary according to the area (e.g.,
In the dental operatory, environmental surfaces          Countertops.                                         dental operatory, laboratory, bathrooms or
(i.e., a surface or equipment that does not contact      Pens.                                                reception rooms), surface and amount and type of
patients directly) can become contaminated               Telephones.                                          contamination.
during patient care. Certain surfaces, especially        Doorknobs.                                           Floors should be cleaned regularly, and spills
ones touched frequently (e.g., light handles,                                                                  should be cleaned up promptly. An EPA-
unit switches and drawer knobs) can serve               Barrier protection of surfaces and equipment
                                                        can prevent contamination of clinical contact          registered hospital disinfectant/detergent
as reservoirs of microbial contamination,                                                                      designed for general housekeeping purposes
                                                        surfaces, but is particularly effective for those
Page 20                                                                                                                                                  Elite CME
should be used in patient-care areas if uncertainty   hypochlorite is chosen, an EPA-registered sodium       requires placement in a second biohazard bag.
exists regarding the nature of the soil on the        hypochlorite product is preferred. However, if         All bags should be securely closed for disposal.
surface (e.g., blood or body fluid contamination      such products are unavailable, a 1:100 dilution of     Puncture-resistant containers with a biohazard
versus routine dust or dirt). Unless contamination    sodium hypochlorite (e.g., approximately ¼ cup         label, located at the point of use (i.e., sharps
is reasonably anticipated or apparent, cleaning       of 5.25 percent household chlorine bleach to 1         containers), are used as containment for scalpel
or disinfecting walls, window drapes and other        gallon of water) is an inexpensive and effective       blades, needles, syringes and unused sterile
vertical surfaces is unnecessary. However, when       disinfecting agent.                                    sharps.
housekeeping surfaces are visibly contaminated
                                                      Carpeting and cloth furnishings                        Dental health care facilities should dispose of
by blood or OPIM, prompt removal and surface
                                                      Carpeting is more difficult to clean than              medical waste regularly to avoid accumulation.
disinfection is appropriate infection control
                                                      nonporous hard surface flooring, and it cannot         Any facility generating regulated medical waste
practice and required by OSHA.
                                                      be reliably disinfected, especially after spills       should have a plan for its management that
Part of the cleaning strategy is to minimize          of blood and body substances. Studies have             complies with federal, state and local regulations
contamination of cleaning solutions and cleaning      documented the presence of diverse microbial           to ensure health and environmental safety.
tools (e.g., mop heads or cleaning cloths).           populations, primarily bacteria and fungi,
Mops and cloths should be cleaned after use
                                                                                                             Discharging blood or other body fluids to
                                                      in carpeting. Cloth furnishings pose similar
and allowed to dry before re-use, or single-use,      contamination risks in areas of direct patient care
                                                                                                             sanitary sewers or septic tanks
disposable mop heads and cloths should be used                                                               All containers with blood or saliva (e.g.,
                                                      and places where contaminated materials are
to avoid spreading contamination.                                                                            suctioned fluids) can be inactivated in accordance
                                                      managed (e.g., dental operatory, laboratory, or
                                                                                                             with state-approved treatment technologies,
Cost, safety, product-surface compatibility           instrument processing areas). For these reasons,
                                                                                                             or the contents can be carefully poured down
and acceptability by housekeepers can be key          use of carpeted flooring and fabric-upholstered
                                                                                                             a utility sink, drain or toilet. Appropriate
criteria for selecting a cleaning agent or an         furnishings in these areas should be avoided.
                                                                                                             protective equipment (e.g., gloves, gown, mask
EPA-registered hospital disinfectant/detergent.       nonregulated and regulated medical                     and protective eyewear) should be worn when
Protective equipment used during cleaning and         waste                                                  performing this task. No evidence exists that
housekeeping procedures should be appropriate         Studies have compared microbial load and               blood-borne diseases have been transmitted from
to the task.                                          diversity of microorganisms in residential waste       contact with raw or treated sewage. Multiple
Another reservoir for microorganisms can              with waste from multiple health care settings.         blood-borne pathogens, particularly viruses, are
be solutions of detergents or disinfectants,          General waste from hospitals or other health           not stable in the environment for long periods,
especially if prepared in dirty containers, stored    care facilities (e.g., dental practices or clinical/   and the discharge of limited quantities of blood
for long periods of time or prepared incorrectly.     research laboratories) is no more infective than       and other body fluids into the sanitary sewer is
Manufacturers’ instructions for preparation and       residential waste. The majority of soiled items        considered a safe method for disposing of these
use should be followed. Making fresh cleaning         in dental offices are general medical waste,           waste materials. State and local regulations vary
solution each day, discarding any remaining           and thus can be disposed of with ordinary              and dictate whether blood or other body fluids
solution and allowing the container to dry will       waste. Examples include used gloves, masks,            require pretreatment or if they can be discharged
minimize bacterial contamination. Preferred           gowns, lightly soiled gauze or cotton rolls, and       into the sanitary sewer and in what volume.
cleaning methods produce minimal mists and            environmental barriers (e.g., plastic sheets or
                                                                                                             Dental unit waterlines, biofilm, and water
aerosols or dispersion of dust in patient care        bags) used to cover equipment during treatment.
areas.                                                Although any item that has had contact with            Studies have demonstrated that dental unit
Cleaning and disinfection strategies for              blood, exudates or secretions might be infective,      waterlines (i.e., narrow-bore plastic tubing that
blood spills                                          treating all such waste as infective is neither        carries water to the high-speed handpiece, air/
The majority of blood contamination events            necessary nor practical. Infectious waste that         water syringe and ultrasonic scaler) can become
in dentistry result from spatter during               carries a substantial risk of causing infection        colonized with microorganisms, including
dental procedures using rotary or ultrasonic          during handling and disposal is regulated medical      bacteria, fungi and protozoa. Protected by
instrumentation. Although no evidence supports        waste. A complete definition of regulated waste        a polysaccharide slime layer known as a
that HBV, HCV or HIV has been transmitted             is included in OSHA’s blood-borne pathogens            glycocalyx, these microorganisms colonize
from a housekeeping surface, prompt removal           standard. Regulated medical waste is only a            and replicate on the interior surfaces of the
and surface disinfection of an area contaminated      limited subset of waste: 9-15 percent of total         waterline tubing and form a biofilm, which serves
by either blood or OPIM are appropriate infection     waste in hospitals and 1-2 percent of total waste      as a reservoir that can amplify the number of
control practices and required by OSHA.               in dental offices.                                     free-floating (i.e., planktonic) microorganisms
                                                      Regulated medical waste requires special storage,      in water used for dental treatment. Although
Strategies for decontaminating spills of blood and                                                           oral flora and human pathogens (e.g.,
other body fluids differ by setting and volume of     handling, neutralization and disposal and is
                                                      covered by federal, state and local rules and          Pseudomonas aeruginosa, Legionella species,
the spill. Blood spills on either clinical contact                                                           and nontuberculous Mycobacterium species),
or housekeeping surfaces should be contained          regulations. Examples of regulated waste found
                                                      in dental-practice settings are solid waste soaked     have been isolated from dental water systems,
and managed as quickly as possible to reduce                                                                 the majority of organisms recovered from
the risk of contact by patients and workers. The      or saturated with blood or saliva (e.g., gauze
                                                      saturated with blood after surgery), extracted         dental waterlines are common heterotrophic
person assigned to clean the spill should wear                                                               water bacteria. These exhibit limited pathogenic
gloves and other protective equipment as needed.      teeth, surgically removed hard and soft tissues,
                                                      and contaminated sharp items (e.g., needles,           potential for immuno-competent persons.
Visible organic material should be removed
with absorbent material (e.g., disposable paper       scalpel blades and wires). Regulated medical           Dental unit water quality
towels discarded in a leak-proof, appropriately       waste requires careful containment for treatment       Research has demonstrated that microbial counts
labeled container). Nonporous surfaces should         or disposal. A single leak-resistant biohazard         can reach 200,000 colony-forming units (CFU)/
be cleaned and then decontaminated with either        bag is usually adequate for containment of             mL within five days after installation of new
an EPA-registered hospital disinfectant effective     nonsharp regulated medical waste, provided the         dental unit waterlines, and levels of microbial
against HBV and HIV or an EPA-registered              bag is sturdy and the waste can be discarded           contamination 106 CFU/mL of dental unit water
hospital disinfectant with a tuberculocidal claim     without contaminating the bag’s exterior.              have been documented. These counts can occur
(i.e., intermediate-level disinfectant). If sodium    Exterior contamination or puncturing of the bag        because dental unit waterline factors (e.g., system

Elite CME                                                                                                                                               Page 21
design, flow rates and materials) promote both       waterlines. For processing any dental device          glove removal, the film should be dried with
bacterial growth and development of biofilm.         that can be removed from the dental unit air          disposable gauze or a paper towel to remove
                                                     or waterlines, neither surface disinfection           blood or excess saliva and placed in a container
Although no epidemiologic evidence indicates a
                                                     nor immersion in chemical germicides is an            (e.g., disposable cup) for transport to the
public health problem, the presence of substantial
                                                     acceptable method. Ethylene oxide gas cannot          developing area. Alternatively, if FDA-cleared
numbers of pathogens in dental unit waterlines
                                                     adequately sterilize internal components of           film barrier pouches are used, the film packets
generates concern. Exposing patients or dental
                                                     handpieces. In clinical evaluations of high-speed     should be carefully removed from the pouch to
workers to water of uncertain microbiological
                                                     handpieces, cleaning and lubrication were the         avoid contamination of the outside film packet
quality, despite the lack of documented adverse
                                                     most critical factors in determining performance      and placed in the clean container for transport to
health effects, is inconsistent with accepted
                                                     and durability. Manufacturer’s instructions for       the developing area. Various methods have been
infection control principles. Thus, in 1995,
                                                     cleaning, lubrication and sterilization should be     recommended for aseptic transport of exposed
ADA addressed the dental water concern by
                                                     followed closely to ensure both the effectiveness     films to the developing area, and for removing the
asking manufacturers to provide equipment
                                                     of the process and the longevity of handpieces.       outer film packet before exposing and developing
with the ability to deliver treatment water with
                                                                                                           the film. Other information regarding dental
less than 200 CFU/mL of unfiltered output            Some components of dental instruments are
                                                                                                           radiography infection control is available.
from waterlines. This threshold was based on         permanently attached to dental unit waterlines,
the quality assurance standard established for       and although they do not enter the patient’s oral     oral surgical procedures
dialysate fluid, to ensure that fluid delivery       cavity, they are likely to become contaminated        The oral cavity is colonized with numerous
systems in hemodialysis units have not been          with oral fluids during treatment procedures.         microorganisms. Oral surgical procedures present
colonized by indigenous waterborne organisms.        Such components (e.g., handles or dental unit         an opportunity for entry of microorganisms (i.e.,
                                                     attachments of saliva ejectors, high-speed air        exogenous and endogenous) into the vascular
Standards also exist for safe drinking water
                                                     evacuators and air/water syringes) should be          system and other normally sterile areas of the
quality as established by EPA, the American
                                                     covered with impervious barriers that are changed     oral cavity (e.g., bone or subcutaneous tissue);
Public Health Association (APHA) and the
                                                     after each use. If the item becomes visibly           therefore, an increased potential exists for
American Water Works Association (AWWA);
                                                     contaminated during use, dental care personnel        localized or systemic infection. Oral surgical
they have set limits for heterotrophic bacteria of
                                                     should clean and disinfect with an EPA-registered     procedures involve the incision, excision or
less than 500 CFU/mL of drinking water. Thus,
                                                     hospital disinfectant (intermediate-level) before     reflection of tissue that exposes the normally
the number of bacteria in water used as a coolant/
                                                     use on the next patient.                              sterile areas of the oral cavity. Examples include
irrigant for nonsurgical dental procedures should
be as low as reasonably achievable and, at a                                                               biopsy, periodontal surgery, apical surgery,
                                                     saliva ejectors
minimum, less than 500 CFU/mL, the regulatory                                                              implant surgery and surgical extractions of
                                                     Backflow from low-volume saliva ejectors occurs
standard for safe drinking water established by                                                            teeth (e.g., removal of erupted or nonerupted
                                                     when the pressure in the patient’s mouth is less
EPA and APHA/AWWA.                                                                                         tooth requiring elevation of mucoperiosteal flap,
                                                     than that in the evacuator. Studies have reported
                                                                                                           removal of bone or section of tooth, and suturing
                                                     that backflow in low-volume suction lines can
special considerations                                                                                     if needed) (see Hand hygiene, PPE, single-use
                                                     occur, and microorganisms can be present in the
Dental handpieces and other devices                                                                        or disposable devices, and Dental unit water
                                                     lines retracted into the patient’s mouth when a
attached to air and waterlines                                                                             quality).
                                                     seal around the saliva ejector is created (e.g., by
Multiple semicritical dental devices that touch      a patient closing their lips around the tip of the    Handling of biopsy specimens
mucous membranes are attached to the air or          ejector, creating a partial vacuum). This backflow    To protect persons handling and transporting
waterlines of the dental unit. Among these           can be a potential source of cross-contamination;     biopsy specimens, each specimen must be placed
devices are high- and low-speed handpieces,          occurrence is variable because the quality of the     in a sturdy, leak-proof container with a secure
prophylaxis angles, ultrasonic and sonic             seal formed varies between patients.                  lid for transportation. Care should be taken when
scaling tips, air abrasion devices and air and
                                                     Furthermore, studies have demonstrated that           collecting the specimen to avoid contaminating
water syringe tips. Although no epidemiologic
                                                     gravity pulls fluid back toward the patient’s         the outside of the container. If the outside of
evidence implicates these instruments in disease
                                                     mouth whenever a length of the suction tubing         the container becomes visibly contaminated, it
transmission, studies of high-speed handpieces
                                                     holding the tip is positioned above the patient’s     should be cleaned and disinfected or placed in an
using dye expulsion have confirmed the
                                                     mouth, or during simultaneous use of other            impervious bag. The container must be labeled
potential for retracting oral fluids into internal
                                                     evacuation (high-volume) equipment. Although          with the biohazard symbol during storage,
compartments of the device. This determination
                                                     no adverse health effects associated with the         transport, shipment and disposal.
indicates that retained patient material can be
expelled intraorally during subsequent uses.         saliva ejector have been reported, practitioners      Handling of extracted teeth disposal
Studies using laboratory models also indicate        should be aware that in certain situations,           Extracted teeth that are being discarded are
the possibility for retention of viral DNA and       backflow could occur when using a saliva ejector.     subject to the containerization and labeling
viable virus inside both high-speed handpieces       Dental radiology                                      provisions outlined by OSHA’s blood-borne
and prophylaxis angles. The potential for            When taking radiographs, the potential to             pathogens standard. OSHA considers extracted
contamination of the internal surfaces of            cross-contaminate equipment and environmental         teeth to be potentially infectious material that
other devices (e.g., low-speed handpieces and        surfaces with blood or saliva is high if aseptic      should be disposed in medical waste containers.
ultrasonic scalers), has not been studied, but       technique is not practiced. Gloves should be          Extracted teeth sent to a dental laboratory for
restricted physical access limits their cleaning.    worn when taking radiographs and handling             shade or size comparisons should be cleaned,
Accordingly, any dental device connected to the      contaminated film packets. Other protective           surface-disinfected with an EPA-registered
dental air/water system that enters the patient’s    equipment (e.g., mask, protective eyewear and         hospital disinfectant with intermediate-level
mouth should be run to discharge water, air or       gowns) should be used if spattering of blood or       activity (i.e., tuberculocidal claim), and
a combination for a minimum of 20-30 seconds         other body fluids is likely. Heat-tolerant versions   transported in a manner consistent with OSHA
after each patient. This procedure is intended       of intraoral radiograph accessories are available,    regulations. However, extracted teeth can be
to help physically flush out patient material        and these semicritical items (e.g., film-holding      returned to patients on request, at which time
that might have entered the turbine and air and      and positioning devices) should be heat-sterilized    provisions of the standard no longer apply.
waterlines.                                          before patient use.                                   Extracted teeth containing dental amalgam should
                                                                                                           not be placed in a medical waste container that
Heat methods can sterilize dental handpieces         After exposure of the radiograph and before           uses incineration for final disposal. Commercial
and other intraoral devices attached to air or
Page 22                                                                                                                                            Elite CME
metal recycling companies also might accept           Program evaluation                                      Adherence to hand        Observe and
extracted teeth with metal restorations, including    The goal of a dental infection control program          hygiene before and       document
amalgam. State and local regulations should be        is to provide a safe working environment that           after patient care.      circumstances
consulted regarding disposal of the amalgam.          will reduce the risk of health care-associated                                   of appropriate
                                                      infections among patients and occupational                                       or inappropriate
M. tuberculosis
                                                      exposures among workers. Medical errors                                          handwashing. Review
Patients infected with M. tuberculosis
                                                      are caused by faulty systems, processes and                                      findings in a staff
occasionally seek urgent dental treatment at
                                                      conditions that lead persons to make mistakes                                    meeting.
outpatient dental settings. Understanding the
                                                      or fail to prevent errors being made by others.
pathogenesis of the development of TB will help                                                               Proper use of            Observe and
                                                      Effective program evaluation is a systematic way
dental care workers determine how to manage                                                                   personal protective      document the use of
                                                      to ensure procedures are useful, feasible, ethical
such patients.                                                                                                equipment to             barrier precautions
                                                      and accurate. Program evaluation is an essential
M. tuberculosis is a bacterium carried in airborne    organizational practice; however, such evaluation       prevent occupational     and careful handling
infective droplet nuclei that can be generated        is not practiced consistently across program            exposures to             of sharps. Review
when persons with pulmonary or laryngeal              areas, nor is it sufficiently well-integrated into      infectious agents.       findings in a staff
TB sneeze, cough, speak or sing. These small          the day-to-day management of the majority of                                     meeting.
particles (1–5 μm) can stay suspended in the air      programs.                                               Routine and              Monitor paper log
for hours. Infection occurs when a susceptible                                                                appropriate              of steam cycle and
                                                      A successful infection control program depends          sterilization of         temperature strip
person inhales droplet nuclei containing M.
                                                      on developing standard operating procedures,            instruments using a      with each sterilization
tuberculosis, which then travel to the alveoli
                                                      evaluating practices, routinely documenting             biologic monitoring      load, and examine
of the lungs. Usually within two to 12 weeks
                                                      adverse outcomes (e.g., occupational exposures          system.                  results of weekly
after initial infection with M. tuberculosis,
                                                      to blood) and work-related illnesses in dental                                   biologic monitoring.
immune response prevents further spread of the
                                                      workers, and monitoring health care-associated                                   Take appropriate
TB bacteria, although they can remain alive in                                                                                         action when failure of
                                                      infections in patients. Strategies and tools to
the lungs for years, a condition termed latent                                                                                         sterilization process
                                                      evaluate the infection control program can
TB infection. Persons with latent TB infection                                                                                         is noted.
                                                      include periodic observational assessments,
usually exhibit a reactive tuberculin skin test
                                                      checklists to document procedures and routine           Evaluation and           Conduct an annual
(TST), have no symptoms of active disease and
                                                      review of occupational exposures to blood-borne         implementation of        review of the
are not infectious. However, they can develop
                                                      pathogens. Evaluation offers an opportunity to          safer medical devices.   exposure control plan
active disease later in life if they do not receive
                                                      improve the effectiveness of both the infection                                  and consider new
treatment for their latent infection.
                                                      control program and dental practice protocols. If                                developments in safer
Any dental worker with a persistent cough (i.e.,      deficiencies or problems in the implementation of                                medical devices.
lasting more than three weeks), especially in the     infection control procedures are identified, further
                                                                                                              Compliance of            Monitor dental
presence of other signs or symptoms compatible        evaluation is needed to eliminate the problems.
                                                                                                              water in routine         water quality as
with active TB (e.g., weight loss, night sweats,      Examples of infection control program evaluation
                                                                                                              dental procedures        recommended by
fatigue, bloody sputum, anorexia or fever),           activities are provided on Table 2.
                                                                                                              with current U.S.        the equipment
should be evaluated promptly. The person should
                                                       TABLE 2. Examples of methods for                       Environmental            manufacturer, using
not return to the workplace until a diagnosis of
                                                       evaluating infection control programs                  Protection Agency        commercial self-
TB has been excluded or he or she is on therapy
                                                                                                              drinking water           contained test kits, or
and has been determined noninfectious by a
                                                       Program element           Evaluation activity          standards (fewer         commercial water-
                                                                                                              than 500 CFU of          testing laboratories.
                                                       Appropriate               Conduct annual               heterotrophic water
Creutzfeldt-Jakob disease and other prion
                                                       immunization of           review of personnel          bacteria).
diseases                                               dental health care        records to ensure
Creutzfeldt-Jakob disease (CJD) belongs to a           personnel (DHCP).         up-to-date                   Proper handling and      Observe the safe
group of rapidly progressive, invariably fatal,                                  immunizations.               disposal of medical      disposal of regulated
degenerative neurological disorders, transmissible                                                            waste.                   and nonregulated
spongiform encephalopathies (TSEs) that affect         Assessment of             Report occupational                                   medical waste and
both humans and animals and are thought to be          occupational              exposures to
                                                                                                                                       take preventive
                                                       exposures to              infectious agents.
caused by infection with an unusual pathogen                                                                                           measures if hazardous
                                                       infectious agents.        Document the steps
called a prion. Prions are isoforms of a normal                                  that occurred around                                  situations occur.
protein, capable of self-propagation although                                    the exposure and plan        Health care–             Assess the
they lack nucleic acid. Prion diseases have an                                   how such exposure            associated infections.   unscheduled return
incubation period of years and are usually fatal                                 can be prevented in                                   of patients after
within one year of diagnosis. Among humans,                                      the future.                                           procedures and
TSEs include CJD, Gerstmann-Straussler-                                                                                                evaluate them for an
                                                       Comprehensive             Ensure the
Scheinker syndrome, fatal familial insomnia,                                                                                           infectious process. A
                                                       postexposure              postexposure
kuru and variant CJD (vCJD). Occurring in                                                                                              trend might require
                                                       management                management plan is
sporadic, familial and acquired (i.e., iatrogenic)                                                                                     formal evaluation.
                                                       plan and medical          clear, complete, and
forms, CJD has an annual incidence in the United
                                                       follow-up program         available at all times
States and other countries of approximately one                                                              infection control research considerations
                                                       after occupational        to all DHCP. All staff
case per million population. In approximately                                                                Although the number of published studies
                                                       exposures to              should understand the
85 percent of affected patients, CJD occurs as a                                                             concerning dental infection control has increased
                                                       infectious agents.        plan, which should
sporadic disease with no recognizable pattern of                                                             in recent years, questions regarding infection
                                                                                 include toll-free
transmission. A smaller proportion of patients (5-                                                           control practices and their effectiveness remain
                                                                                 phone numbers for
15 percent) experience familial CJD because of                                                               unanswered. Multiple concerns were identified by
                                                                                 access to additional
inherited mutations of the prion protein gene.                                                               the working group for a CDC report, as well as
                                                                                                             by others during a public comment period.
Elite CME                                                                                                                                               Page 23
This list is not exhaustive and does not represent   Clinical and population-based epidemiologic          containing microorganisms that can remain
a CDC research agenda, but rather is an              research and development                             suspended in the air for long periods of time.
effort to identify certain concerns, stimulate        Continue to characterize the epidemiology
                                                                                                          Endotoxin – The lipopolysaccharide of gram-
discussion, and provide direction for determining        of blood contacts, particularly percutaneous
                                                                                                          negative bacteria, the toxic character of which
future action by clinical, basic science and             injuries, and the effectiveness of prevention
                                                                                                          resides in the lipid protein. Endotoxins can
epidemiologic investigators, as well as health and       measures.
                                                                                                          produce pyrogenic reactions in persons exposed
professional organizations, clinicians and policy     Further assess the effectiveness of double
                                                                                                          to their bacterial component.
makers.                                                  gloving in preventing blood contact during
                                                         routine and surgical dental procedures.          HCP – Health care personnel/professionals
Education and promotion
                                                      Continue to assess the stress placed on gloves     include doctors, nurses, radiologist, laboratory
 Design strategies to communicate, to the
                                                         during dental procedures and the potential       technicians, pharmacists, assistants, (in-
   public and providers, the risk of disease
                                                         for developing defects during different          office and commercial), students and trainees,
   transmission in dentistry.
                                                         procedures.                                      contractual personnel, and other persons not
 Promote use of protocols for recommended
                                                      Develop methods for evaluating the                 directly involved in patient care but potentially
   postexposure management and follow-up.
                                                         effectiveness and costeffectiveness of           exposed to infectious agents (e.g., administrative,
 Educate and train dental health care
   personnel (DHCP) to screen and evaluate               infection control interventions.                 clerical, housekeeping, maintenance, or volunteer
   safer dental devices by using tested design        Determine how infection control guidelines         personnel) working in a health care facility.
   and performance criteria.                             affect the knowledge, attitudes, and practices
                                                                                                          HCW – Health care worker includes anyone
Laboratory-based research                                of dental workers.
                                                                                                          working in a health care facility of any kind
 Develop animal models to determine the risk        Selected definitions                                 whenever there is potential contact for spattering
   of transmitting organisms through inhalation      Alcohol-based hand rub – An alcohol-                 of blood or OPIM.
   of contaminated aerosols (e.g., influenza)        containing preparation designed for reducing the
   produced from rotary dental instruments.          number of viable microorganisms on the hands.        Hepatitis B immune globulin (HBIG) – Product
 Conduct studies to determine the                                                                        used for prophylaxis against HBV infection.
   effectiveness of gloves (i.e., material           Antiseptic – A germicide used on skin or living      HBIG is prepared from plasma containing high
   compatibility and duration of use).               tissue for the purpose of inhibiting or destroying   titers of hepatitis B surface antibody (anti-HBs)
 Develop devices with passive safety features       microorganisms (e.g., alcohols, chlorhexidine,       and provides protection for 3–6 mos.
   to prevent percutaneous injuries.                 chlorine, hexachlorophene, iodine, chloroxylenol
                                                     [PCMX], quaternary ammonium compounds, and           Hepatitis B surface antigen (HBsAg) –
 Study the effect of alcohol-based hand-                                                                 Serologic marker on the surface of HBV detected
   hygiene products on retention of latex            triclosan).
                                                                                                          in high levels during acute or chronic hepatitis.
   proteins and other dental allergens (e.g.,        Bead sterilizer – A device using glass beads         The body normally produces antibodies to
   methyl methacrylate, glutaraldehyde,              1.2–1.5 mm diameter and temperatures 217ºC–          surface antigen as a normal immune response to
   thiurams) on the hands of workers after latex     232ºC for brief exposures (e.g., 45 seconds) to      infection.
   glove use.                                        inactivate microorganisms. (This term is actually
 Investigate the applicability of other types       a misnomer because it has not been cleared by        Hepatitis B e-antigen (HBeAg) – Secreted
   of sterilization procedures (e.g., hydrogen       the Food and Drug Administration [FDA] as a          product of the nucleocapsid gene of HBV found
   peroxide gas plasma) in dentistry. Encourage      sterilizer).                                         in serum during acute and chronic HBV infection.
   manufacturers to determine optimal methods                                                             Its presence indicates that the virus is replicating
   and frequency for testing dental-unit             Bioburden – Microbiological load (i.e., number       and serves as a marker of increased infectivity.
   waterlines and maintaining dental-unit water-     of viable organisms in or on an object or surface)
                                                     or organic material on a surface or object before    Hepatitis B surface antibody (anti-HBs) –
   quality standards.                                                                                     Protective antibody against HBsAg. Presence in
 Determine the potential for internal               decontamination, or sterilization. Also known as
                                                     bioload or microbial load.                           the blood can indicate past infection with, and
   contamination of low-speed handpieces,                                                                 immunity to, HBV, or immune response from
   including the motor, and other devices            Colony-forming unit (CFU) – The minimum              hepatitis B vaccine.
   connected to dental air and water supplies,       number (i.e., tens of millions) of separable cells
   as well as more efficient ways to clean,          on the surface of or in semisolid agar medium        Heterotrophic bacteria – Those bacteria
   lubricate, and sterilize handpieces and other     that give rise to a visible colony of progeny.       requiring an organic carbon source for growth
   devices attached to air or waterlines.            CFUs can consist of pairs, chains, clusters, or as   (i.e., deriving energy and carbon from organic
 Investigate the infectivity of oral tissues in     single cells and are often expressed as colony-      compounds).
   Creutzfeldt-Jakob disease (CJD) or variant        forming units per milliliter (CFUs/mL).              Iatrogenic – Induced inadvertently by HCP,
   CJD patients.                                                                                          medical (including dental) treatment, or
 Determine the most effective methods to            DHCP – Dental health care personnel/
                                                     professionals (DHCP) include dentists, dental        diagnostic procedures. Used particularly in
   disinfect dental impression materials.                                                                 reference to an infectious disease or other
 Investigate the viability of pathogenic            hygienists, dental assistants, dental laboratory
                                                     technicians (in-office and commercial), students     complication of treatment.
   organisms on dental materials (e.g.,
   impression materials, acrylic resin, or           and trainees, contractual personnel, and other       Nosocomial – Infection acquired in a hospital
   gypsum materials) and dental laboratory           persons not directly involved in patient care        as a result of medical care.
   equipment.                                        but potentially exposed to infectious agents
                                                     (e.g., administrative, clerical, housekeeping,       OPIM – Other potentially infectious materials.
 Determine the most effective methods                                                                    OPIM is an OSHA term that refers to: 1.) Body
   for sterilization or disinfection of digital      maintenance, or volunteer personnel). Working
                                                     in a dental health care facility.                    fluids including semen, vaginal secretions,
   radiology equipment.                                                                                   cerebrospinal fluid, synovial fluid, pleural fluid,
 Evaluate the effects of repetitive reprocessing    Dental treatment water – Nonsterile water used       pericardial fluid, peritoneal fluid, amniotic fluid,
   cycles on burs and endodontic files.              during dental treatment, including irrigation of     saliva in dental procedures; any body fluid visibly
 Investigate the potential infectivity of vapors    nonsurgical operative sites and cooling of high-     contaminated with blood; and all body fluids in
   generated from the various lasers used for        speed rotary and ultrasonic instruments.             situations where differentiating between body
   oral procedures.                                                                                       fluids is difficult or impossible; 2.) Any unfixed
                                                     Droplet nuclei – Particles <5 μm in diameter
                                                     formed by dehydration of airborne droplets           tissue or organ (other than intact skin) from a

Page 24                                                                                                                                            Elite CME
human (living or dead); and 3.) HIV-containing                                                                         NOTES
cell or tissue cultures, organ cultures; HIV- or                        guiDELinEs FoR inFECTion
HBV-containing culture medium or other                               ConTRoL in DEnTAL HEALTH CARE
solutions; and blood, organs, or other tissues from                             sETTings
experimental animals infected with HIV or HBV.                              Final Examination Exercises
Prion – Protein particle lacking nucleic acid                             Choose True or False for questions
that has been implicated as the cause of certain                      1 through 5 and mark your answers on the
neurodegenerative diseases (e.g., scrapie, CJD,                           Final Examination Sheet found on
and bovine spongiform encephalopathy [BSE]).                              page 109 or take your test online at
Retraction – Entry of oral fluids and
microorganisms into waterlines through negative
water pressure.                                                     1. Avoiding exposure to blood and OPIM
                                                                       as well as protection by immunization
Seroconversion – The change of a serological
                                                                       remain primary strategies for reducing
test from negative to positive indicating the
                                                                       occupationally acquired infections, but
development of antibodies in response to
                                                                       occupational exposures can still occur.
infection or immunization.
                                                                             True                False
Sterile – Free from all living microorganisms;
usually described as a probability (e.g., the
probability of a surviving microorganism being 1                    2. Standard precautions are strategies used to
in 1 million).                                                         reduce the risk of infection from exposure
                                                                       to blood, all body fluids and secretions
Sterilization – Use of a physical or chemical                          (except sweat), nonintact skin and mucous
procedure to destroy all microorganisms                                membranes.
including substantial numbers of resistant
bacterial spores.                                                            True                False

                                                                    3. There is evidence that shows using
Dental health care professionals are at risk
                                                                       antiseptics for wound care or expressing
everyday, but here we have seen many infection
                                                                       fluid by squeezing the wound further
control practices a dentist, his staff and his
                                                                       reduces the risk of blood-borne pathogen
patients can take to reduce those risks By taking
the sterilization precautions, developing a written
plan for the key elements of an infection control                            True                False
process, maintaining the necessary records,
evaluating the plan on a routine basis and making                   4. Dental devices that are connected to the
changes to keep the processes up-to-date, the goal                     dental water system and that enter the
of minimizing the risk of disease transmission in                      patient’s mouth (e.g., handpieces, ultrasonic
the dental office can be met.                                          scalers or air/water syringes) should be
References                                                             operated to discharge water and air for
sCDC. Guidelines for Infection Control in Dental Health care
Setings-2003. MMWR Dec 19, 2003/Vol. 52/ No. RR-17.                    a minimum of 5-10 seconds after each
sProvisions Applicable To All Licensees, Article 1. Section 1005.      patient.
Minimum Standards for Infection Control.
                                                                             True                False

                                                                    5. Sterilization is the use of a physical
                                                                       or chemical procedure to destroy all
                                                                       microorganisms, including substantial
                                                                       numbers of resistant bacterial spores.
                                                                             True                False

Elite CME                                                                                                                      Page 25
                   CHAPTER 3                           and Observations on Different Kinds of Air”            nitrous oxide for the medical faculty in Boston,
           niTRous oxiDE – n2o                         (1775), where he described how to produce the          leaving his colleagues doubtful regarding its
                   (7 CE Hours)                        preparation of “nitrous air diminished” by heating     efficacy and safety.
Learning objectives                                    iron filings dampened with nitric acid.                The method did not come into general use until
!   Review the history of nitrous oxide.               Early use (1794-1843)                                  1863, when Colton successfully started to use it
!   Describe the production of nitrous oxide.          The first important use of nitrous oxide was made      in all his Colton Dental Association clinics, which
!   List the uses of nitrous oxide.                    possible by Thomas Beddoes and the renowned            he just had established in New Haven and New
!   Explain the use of nitrous oxide in dental         engineer James Watt, who worked together to            York City. Over the following three years, Colton
    operatories.                                       publish the book “Considerations on the Medical        and his associates successfully administered
!   Describe the hazards in the workplace.             Use and on the Production of Factitious Airs”          nitrous oxide to more than 25,000 patients. With
!   Review the methods of engineering control          (1794). This book was important for two reasons.       its efficacy and safety now demonstrated by
    and training.                                      First, James Watt had invented a novel machine         large numbers, the usage of nitrous oxide rapidly
                                                       to produce “factitious airs” (i.e. nitrous oxide)      became the preferred anesthetic method in
                                                       and a novel “breathing apparatus” to inhale            dentistry. Because the gas is mild enough to keep
Sedation dentistry, sometimes called relaxation
                                                       the gas. Second, the book also presented the           a patient in a conscious and conversational state
dentistry, refers to the way dentists manage pain
                                                       new medical theories by Thomas Beddoes, that           but in most cases is strong enough to suppress
and anxiety during dental appointments.
                                                       tuberculosis and other lung diseases could be          the pain caused by dental work, it remains the
Conscious sedation is defined as a minimally           treated by inhalation of factitious airs.              preferred agent in dentistry today.
depressed level of consciousness that retains                                                                 In hospitals, however, nitrous oxide was
the patient’s ability to independently and             The machine to produce factitious airs was
                                                       comprised of three parts: a furnace to burn the        found not to be a strong enough for use
continuously maintain an airway and respond                                                                   in large operations. A stronger and more
appropriately to physical stimulation and verbal       needed material, a vessel with water where the
                                                       produced gas passed through in a spiral pipe (in       potent anesthetic, sulfuric ether, was instead
command that is produced by pharmacological or                                                                demonstrated and accepted for use in October
nonpharmacologic method or a combination of            order for impurities to be “washed off”), and
                                                       finally the gas cylinder with a gasometer where        1846, along with chloroform in 1847. When
both. Nitrous oxide is only one of the 14 different                                                           Joseph Thomas Clover invented the “gas-ether
ways that sedation drugs can be administered.          the produced air could be tapped into portable air
                                                       bags (made of airtight oily silk). The breathing       inhaler” in 1876, it became a common practice at
There are three primary ways that sedation is                                                                 hospitals to initiate all anesthetic treatments with
administered in the dental office: IV sedation,        apparatus was one of the portable air bags
                                                       connected with a tube to a mouthpiece. With this       a mild flow of nitrous oxide, and then gradually
enteral conscious sedation and inhalation                                                                     increase the anesthesia with the stronger ether/
conscious sedation or nitrous oxide.                   new equipment engineered and produced already
                                                       in 1794, the way was now paved for clinical            chloroform. Clover’s gas-ether inhaler was
                                                       trials, which began when Thomas Beddoes in             designed to supply the patient with nitrous
                                                       1798 established the Pneumatic Institution for         oxide and ether at the same time, with the exact
                                                       Relieving Diseases by Medical Airs in Clifton          mixture controlled by the operator of the device.
                                                       (Bristol). In the basement of the building, a large-   It remained in use by many hospitals until the
                                                       scale machine was producing the gases under            1930s. Although hospitals today are using a more
                                                       the supervision of a young Humphry Davy, who           advanced anesthetic machine, these machines still
                                                       was encouraged to experiment with new gases            use the same principle launched with Clover’s
                                                       for patients to inhale. The first important work of    gas-ether inhaler, to initiate the anesthesia with
                       N2O                             Davy was to examine the nitrous oxide, with the        nitrous oxide before the administration of a more
Inhalation conscious sedation or the use of            results being published in his book: “Researches,      powerful anesthetic.
nitrous oxide, commonly known as laughing gas,         Chemical and Philosophical” (1800).                    Production
is a chemical compound with the formula N2O. It        Despite the valuable finding made by Davy,             Nitrous oxide is most commonly prepared by
is an oxide of nitrogen. At room temperature, it       that inhalation of nitrous oxide could relieve a       careful heating of ammonium nitrate, which
is a colorless non-flammable gas with a pleasant,      conscious person from pain, another 44 years           decomposes into nitrous oxide and water vapor.
slightly sweet odor and taste. It is used in surgery   would elapse before doctors attempted to use it        The addition of various phosphates favors
and dentistry for its anesthetic and analgesic         for anesthesia.                                        formation of a purer gas at slightly lower
effects. It is known as “laughing gas” because of                                                             temperatures. One of the earliest commercial
the euphoric effects of inhaling it, a property that   Anesthetic use                                         producers was George Poe in Trenton, New
has led to its recreational use as a dissociative      At a “popular science” exhibition in Hartford,         Jersey.
hallucinogen. It is also used as an oxidizer in        Connecticut, where volunteers inhaled nitrous           NH4NO3 (s) → 2 H2O (g) + N2O (g)
rocketry and in motor racing to increase the           oxide, local dentist Horace Wells noted one of             Š This reaction occurs between 170-
power output of engine. At elevated temperatures,      them, a man who had injured his leg, seemed                    240 degrees C, temperatures where
nitrous oxide is a powerful oxidizer similar to        unaware of any pain from the injury. Thus                      ammonium nitrate is a moderately
molecular oxygen. For example, nitrous oxide in        was the born the first use of nitrous oxide as                 sensitive explosive and a very powerful
a test tube will re-ignite a smoldering splint.        anesthetic drug. Wells himself, with assistance by             oxidizer. Above 240 degrees C, the
                                                       Gardner Quincy Colton and John Mankey Riggs,                   exothermic reaction may accelerate to
Nitrous oxide reacts with ozone and is the main
                                                       demonstrated insensitivity to pain from a dental               the point of detonation, so the mixture
naturally occurring regulator of stratospheric
                                                       extraction in December 1844. In the following                  must be cooled to avoid such a disaster.
ozone. It is also a major greenhouse gas and air
                                                       weeks, Wells treated the first 12-15 patients with             Superheated steam is used to reach
pollutant. Considered over a 100-year period, it
                                                       nitrous oxide in Hartford, and according to his                reaction temperature in some turnkey
has 298 times more impact per unit weight than
                                                       own record, only failed in two cases. In spite of              production plants.
carbon dioxide.
                                                       these convincing results reported by Wells to the
                                                       medical society in Boston in December 1844,            Downstream, the hot, corrosive mixture of gases
                                                       this new method was not immediately adopted            must be cooled to condense the steam and filtered
The gas was first synthesized by English chemist
                                                       by other dentists. This probably was because in        to remove higher oxides of nitrogen. Ammonium
and Unitarian minister Joseph Priestley in 1772,
                                                       January 1845, Wells had been partly unsuccessful       nitrate smoke, as an extremely persistent colloid,
who called it phlogisticated nitrous air. Priestley
                                                       at his first public demonstration of the use of        will also have to be removed. The cleanup is
published his discovery in the book “Experiments
Page 26                                                                                                                                                Elite CME
often done in a train of three gas washes, base,       In a 1914 patent, American rocket pioneer Robert      technological considerations limited its use to
acid and base again. However, significant              Goddard suggested nitrous oxide and gasoline as       extremely high altitudes. Accordingly, it was
amounts of nitric oxide (NO) may not necessarily       possible propellants for a liquid-fueled rocket.      only used by specialized planes like high-altitude
be absorbed directly by the base (sodium               Nitrous oxide has been the oxidizer of choice         reconnaissance aircraft, high-speed bombers and
hydroxide) washes.                                     in several hybrid rocket designs (using solid         high-altitude interceptor aircraft.
The nitric oxide impurity is sometimes chelated        fuel with a liquid or gaseous oxidizer). The
                                                                                                             One of the major problems of using nitrous oxide
out with ferrous sulfate, reduced with iron metal      combination of nitrous oxide with hydroxyl-
                                                                                                             in a reciprocating engine is that it can produce
or oxidized and absorbed in base as a higher           terminated polybutadiene fuel has been used by
                                                                                                             enough power to damage or destroy the engine.
oxide. The first base wash may (or may not)            SpaceShipOne and others. It is also notably used
                                                                                                             Very large power increases are possible, and if the
react out much of the ammonium nitrate smoke.          in amateur and high power rocketry with various
                                                                                                             mechanical structure of the engine is not properly
However, this reaction generates ammonia gas,          plastics as the fuel.
                                                                                                             reinforced, the engine may be severely damaged
which may have to be absorbed in the acid wash.
                                                       Nitrous oxide can also be used in a                   or destroyed during this kind of operation. It is
other routes                                           monopropellant rocket. In the presence                very important with nitrous oxide augmentation
The direct oxidation of ammonia may someday            of a heated catalyst, N2O will decompose              of internal combustion engines to maintain proper
rival the ammonium nitrate pyrolysis synthesis         exothermically into nitrogen and oxygen, at a         operating temperatures and fuel levels to prevent
of nitrous oxide mentioned above. This capital-        temperature of approximately 1,300 degrees            “pre-ignition” or “detonation” (sometimes
intensive process, which originates in Japan, uses     C. Because of the large heat release, the             referred to as “knocking” or “pinging”). Most
a manganese dioxide-bismuth oxide catalyst:            catalytic action rapidly becomes secondary            problems that are associated with nitrous do not
 2 NH3 + 2 O2 → N2O + 3 H2O                           as thermal autodecomposition becomes                  come from mechanical failure due to the power
    Š Higher oxides of nitrogen are formed as          dominant. In a vacuum thruster, this can              increases. Since nitrous allows a much denser
         impurities. In comparison, uncatalyzed        provide a monopropellant specific impulse             charge into the cylinder, it dramatically increases
         ammonia oxidation (i.e. combustion or         (Isp) of as much as 180s. While noticeably less       cylinder pressures. The increased pressure and
         explosion) goes primarily to N2 and H2O.      than the Isp available from hydrazine thrusters       temperature can cause problems, such as melting
                                                       (monopropellant or bipropellant with nitrogen         the piston or valves. It may also crack or warp
Nitrous oxide can be made by heating a solution
                                                       tetroxide), the decreased toxicity makes nitrous      the piston or head and cause pre-ignition due to
of sulfamic acid and nitric acid. Many gases are
                                                       oxide an option worth investigating.                  uneven heating.
made this way in Bulgaria.
 HNO3 + NH2SO3H → N2O + H2SO4 + H2O                   Specific impulse (Isp) can be improved by             Aerosol propellant
    Š There is no explosive hazard in this             blending a hydrocarbon fuel with the nitrous          The gas is approved for use as a food additive
        reaction if the mixing rate is controlled.     oxide inside the same storage tank, becoming a        (also known as E942), specifically as an aerosol
        However, as usual, toxic higher oxides of      nitrous oxide fuel blend (NOFB) monopropellant.       spray propellant. Its most common uses in this
        nitrogen are formed.                           This storage mixture does not incur the danger of     context are in aerosol whipped cream canisters,
                                                       spontaneous ignition because N2O is chemically        cooking sprays and as an inert gas used to
Nitrous oxide is produced in large volumes as
                                                       stable. When the nitrous oxide decomposes by          displace oxygen and inhibit bacterial growth
a byproduct in the synthesis of adipic acid, one
                                                       a heated catalyst, high-temperature oxygen is         when filling packages of potato chips and other
of the two reactants used in nylon manufacture.
                                                       released and rapidly ignites the hydrocarbon fuel     similar snack foods.
This might become a major commercial source,
                                                       blend. NOFB monopropellants are capable of
but will require the removal of higher oxides                                                                The gas is extremely soluble in fatty compounds.
                                                       Isp greater than 300 seconds, while avoiding the
of nitrogen and organic impurities. Currently,                                                               In aerosol whipped cream, it is dissolved in
                                                       toxicity associated with hypergolic propulsion
much of the gas is decomposed before release                                                                 the fatty cream until it leaves the can, when it
                                                       systems. The low freezing point of NOFB eases
for environmental protection. Greener processes                                                              becomes gaseous and thus creates foam. Used in
                                                       thermal management compared to hydrazine and
may prevail that substitute hydrogen peroxide                                                                this way, it produces whipped cream four times
                                                       dinitrogen tetroxide – a valuable property for
for nitric acid oxidation; hence no generation of                                                            the volume of the liquid, whereas whipping air
                                                       space storable propellants.
oxide of nitrogen by-products.                                                                               into cream only produces twice the volume. If
                                                       internal combustion engine                            air were used as a propellant, oxygen would
Hydroxylammonium chloride can react with
                                                       In vehicle racing, nitrous oxide (often referred      accelerate rancidification of the butterfat; nitrous
sodium nitrite to produce N2O as well:
                                                       to as just “nitrous” or as NOS after the name of      oxide inhibits such degradation. Carbon dioxide
 NH3OH+Cl− + NaNO2 → N2O + NaCl + 2
                                                       the brand Nitrous Oxide Systems) allows the           cannot be used for whipped cream because it is
                                                       engine to burn more fuel and air, resulting in        acidic in water, which would curdle the cream
    Š If the nitrite is added to the
                                                       a more powerful combustion. The gas itself is         and give it a seltzer-like “sparkling” sensation.
       hydroxylamine solution, the only
                                                       not flammable, but it delivers more oxygen than
       remaining byproduct is salt water.                                                                    However, the whipped cream produced with
                                                       atmospheric air by breaking down at elevated
       However, if the hydroxylamine solution                                                                nitrous oxide is unstable and will return to a
       is added to the nitrite solution (nitrite is                                                          liquid state within half an hour to one hour. Thus,
       in excess), then toxic higher oxides of         Nitrous oxide is stored as a compressed liquid;       the method is not suitable for decorating food that
       nitrogen are also formed.                       the evaporation and expansion of liquid nitrous       will not be immediately served.
                                                       oxide in the intake manifold causes a large drop
Applications                                                                                                 Similarly, cooking spray, which is made from
                                                       in intake charge temperature, resulting in a denser
Rocket motors                                                                                                various types of oils combined with lecithin (an
                                                       charge, further allowing more air/fuel mixture
Nitrous oxide can be used as an oxidizer in a                                                                emulsifier), may use nitrous oxide as a propellant;
                                                       to enter the cylinder. Nitrous oxide is sometimes
rocket motor. This has the advantages over other                                                             other propellants used in cooking spray include
                                                       injected into (or prior to) the intake manifold,
oxidizers that it is non-toxic, and because of its                                                           food-grade alcohol and propane.
                                                       whereas other systems directly inject right before
stability at room temperature, easy to store and       the cylinder (direct port injection) to increase      Users of nitrous oxide for recreational use as a
relatively safe to carry on a flight. As a secondary   power.                                                euphoria-inducing inhalant drug, often obtain it
benefit, it can be readily decomposed to form                                                                from whipped cream dispensers that use nitrous
breathing air. Its high density and low storage        The technique was used during World War II by
                                                                                                             oxide as a propellant. It is not harmful in small
pressure enable it to be highly competitive with       Luftwaffe aircraft with the GM-1 system to boost
                                                                                                             doses, but risks due to lack of oxygen do exist
stored high-pressure gas systems.                      the power output of aircraft engines. Originally
                                                                                                             (see Recreational section).
                                                       meant to provide the Luftwaffe standard aircraft
                                                       with superior high-altitude performance,
Elite CME                                                                                                                                                 Page 27
Recreational use                                     propellants to create whipped cream – declined         The typical abuser of nitrous oxide is older and
Nitrous oxide (N2O) is a dissociative drug that      between 2002 and 2007 among males (40.2                middle- or upper class, they said. If the abuser
can cause analgesia, depersonalization, dizziness,   percent to 20.2 percent) and females (22.3             has an inhalation sedation unit available, it may
euphoria and some sound distortion. Research         percent to 21.2 percent).                              have been altered to deliver a higher concentrate
has also found that it increases suggestibility                                                             of gas, they said.
                                                     However, an investigation in 2009 by the
and imagination. Inhalation of nitrous oxide for     Bristol (Va.) Herald Courier reported that the         The authors noted there have been reports of
recreational use to cause euphoria and slight        records of 46 health care professionals in the         sexual abuse of patients under anesthetics,
hallucinations began as a phenomenon for the         area – including doctors, nurses, pharmacists and      including nitrous oxide. They noted there are
British upper class in 1799 at “laughing gas         dentists – were “marred by substance abuse, and        three elements that put a practitioner at risk:
parties.” When equipment became more widely          in some cases, criminal convictions.”                  treating a patient without an assistant in the
available for dentistry and hospitals, most                                                                 operatory, high concentrations of nitrous oxide,
countries also restricted the legal access to buy    The Herald Courier told the story of a Big Stone
                                                                                                            and failure to titrate the patient to avoid extension
pure nitrous oxide gas cylinders to those sectors.   Gap, Va., dentist who “huffed nitrous oxide in the
                                                                                                            of therapeutic sedation.
A low availability of equipment to produce the       mid-1970s and quit only after a temporary loss
gas combined with a low usage of the gas for         of feeling in his hands.” From there, the dentist      “Nitrous oxide should be employed with
medical purposes meant recreational use was          descended into alcoholism and took Valium and          confidence. Employing simple guidelines will
a relatively rare phenomenon that mainly took        Hydrocodone from his office, the newspaper said.       ensure there are no difficulties with sexual issues
place among students at medical universities.                                                               and the administrator of nitrous oxide,” they said.
                                                     A grassroots drug-recovery group of Virginia
That apparently continued into the 20th century. A   dentists directed the man to a rehab program. The      in medicine
poll taken in 1979 indicated that between 1 and      state board of dentistry got an anonymous call         Nitrous oxide has been used for anesthesia in
2 percent of medical and dental students used        about his situation. Instead of disciplinary action,   dentistry since December 1844, when Horace
nitrous oxide for recreational purposes, according   the board helped monitor his recovery. According       Wells made the first dental operations with
to Theodore J. Jastak in a 1991 article in the       to the newspaper, keeping addictions confidential      the gas in Hartford. Its debut as a generally
Journal of the American Dental Association.          is at the discretion of either a Department of         accepted method came in 1863, when Gardner
In the 1960 and ’70s, the recreational use of        Health Professions investigator or a licensing         Quincy Colton introduced it more broadly at all
inhalants became somewhat fashionable again,         board.                                                 the Colton Dental Association clinics. The first
according to a Consumers Union report in             A board of medicine official said the policy           devices used in dentistry to administer the gas,
1972 based on reports of use in Maryland and         protected the public by “making sure the               known as nitrous oxide inhalers, were designed
Vancouver and a survey at the University of          individual is identified and investigated, set         in a very simple way, with the gas stored and
Michigan in 1970.                                    for an evaluation and treatment, and continue          breathed through a breathing bag made of rubber
                                                     with monitoring. They (the Virginia monitoring         cloth, without a scavenger system and flow meter,
According to the Michigan survey: “It was not
                                                     program) will not OK a doctor to go back into          and with no addition of oxygen/air.
uncommon [in the interviews] to hear from
individuals who had been to parties where a          practice until he or she is believed to be safe.”      Today these simple and somewhat unreliable
professional (doctor, nurse, scientist, inhalation   That is a common practice. The Federation of           inhalers, of course, have been replaced by the
therapist, researcher) had provided nitrous oxide.   State Physician Health Programs Inc. (FSPHP)           more modern relative analgesia machine, which
There also were those who work in restaurants        evolved in 1990 from an initiative of the              is an automated machine designed to deliver
who used the N2O stored in tanks for the             American Medical Association and individual            a precisely dosed and breath-actuated flow of
preparation of whip cream. Reports were received     state physician health programs that focus upon        nitrous oxide mixed with oxygen for the patient
from individuals who used the gas contained in       rehabilitation and monitoring of physicians with       to inhale safely. The machine used in dentistry
aerosol cans both of food and non-food products.     psychoactive substance abuse disorders as well         is designed as a more simplified version of the
At a rock festival, nitrous oxide was widely sold    as mental and physical illness. The nonprofit          larger anesthetic machine used by hospitals,
for 25 cents a balloon. Contact was made with        organization includes members from 42 state            and it doesn’t feature the additional anesthetic
a ‘mystical-religious’ group that used the gas       programs.                                              vaporizer and medical ventilator. The machine
to accelerate arriving at their transcendental-                                                             allows for a more simple design, because it only
meditative state of choice. Although a few more      FSPHP serves as a resource for state programs;         delivers a mixture of nitrous oxide and oxygen
sophisticated users employed nitrous oxide-          helps to establish monitoring standards; serves        for the patient to inhale to depress the feeling
oxygen mixes with elaborate equipment, most          as an informational source; advocates for              of pain while keeping the patient in a conscious
users employed balloons or plastic bags. They        physicians and their health issues at local state      state.
either held a breath of N2O or rebreathed the gas.   and national levels; and helps states in their quest
                                                     to protect the public. The organization promotes       The relative analgesia machine typically features
There were no adverse effects reported in the
                                                     confidentiality for health care professionals who      a constant-supply flow meter, which allows the
more than 100 individuals surveyed.”
                                                     chose to address their substance problems and          proportion of nitrous oxide and the combined gas
Although recreational use is believed to be          submit to rigorous monitoring of their progress.       flow rate to be individually adjusted. The gas is
somewhat limited today, government data on                                                                  administered by dentists through a demand-valve
substance abuse of youths shows that inhalants,      A 2003 report in the Journal of the California         inhaler over the nose, which will only release
including nitrous oxide, are being used by young     Dental Association [Malamed and Clark] cited           gas when the patient inhales through the nose.
people.                                              concerns about abuse of nitrous oxide by health        Because nitrous oxide is minimally metabolized
                                                     care professionals. The authors said nitrous           in humans (with a rate of 0.004 percent), it
The Substance Abuse and Mental Health Services       oxide causes euphoria and can include “sexual          retains its potency when exhaled into the room
Administration (SAMHSA) said in its 2007             phenomena,” including increased feelings of            by the patient and can pose an intoxicating and
report on trends in drug use that almost 1 million   sexuality and arousal, and therefore has the           prolonged exposure hazard to the clinic staff
youth had used inhalants within the past year. The   potential for abuse. “This abuse is usually not        if the room is poorly ventilated. Where nitrous
percentage of young people aged 12-17 who had        as addictive as some drugs, but nonetheless can        oxide is administered, a continuous-flow fresh-air
used all inhalants within the past year was lower    be a steppingstone to other drugs and can cause        ventilation system or nitrous scavenger system is
in 2007 (3.9 percent) than in 2003 (4.5 percent),    incapacitation of the affected person. Nitrous         used to prevent a waste-gas buildup.
in 2004 (4.6 percent), and in 2005 (4.5 percent).    oxide should be given the same respect as all
Among first-time users, the rate of use of nitrous   drugs.”                                                Hospitals are administering nitrous oxide as one
oxide, or “whippets” – usually canisters of the                                                             of the anesthetic drugs delivered by anesthetic
Page 28                                                                                                                                               Elite CME
machines. Nitrous oxide is a weak general             given directly to the spinal cord, but not when        the administration of anesthetic gas in medical,
anesthetic, and so is generally not used alone        applied directly to the brain. Indeed, α2B-            dental and veterinary operators.
in general anesthesia. In general anesthesia it is    adrenoceptor knockout mice or animals depleted
used as a carrier gas in a 2:1 ratio with oxygen      in norepinephrine are nearly completely resistant
                                                                                                             At room temperature (20 degrees C), the
for more powerful general anesthetic, drugs           to the anti-nociceptive effects of N2O. It seems
                                                                                                             saturated vapor pressure is 58.5 bar, rising up
such as sevoflurane or desflurane. It has a MAC       N2O-induced release of endogenous opioids
                                                                                                             to 72.45 bar at 36.4 degrees C – the critical
(minimum alveolar concentration) of 105 percent       causes disinhibition of brain stem noradrenergic
                                                                                                             temperature. The pressure curve is thus unusually
and a blood gas partition coefficient of 0.46.        neurons, which release norepinephrine into the
                                                                                                             sensitive to temperature. Liquid nitrous oxide acts
                                                      spinal cord and inhibit pain signaling. Exactly
When nitrous oxide is inhaled as the only                                                                    as a good solvent for many organic compounds;
                                                      how N2O causes the release of endogenous opioid
anesthetic drug, it is normally administered as                                                              liquid mixtures may form shock-sensitive
                                                      peptides is still uncertain.
a mixture with 30 percent gas and 70 percent                                                                 explosives.
oxygen.                                               Euphoric effect
                                                                                                             As with many strong oxidizers, contamination of
                                                      In rats, N2O stimulates the mesolimbic reward
neuropharmacology                                                                                            parts with fuels have been implicated in rocketry
                                                      pathway via inducing dopamine release and
The pharmacological mechanism of action of                                                                   accidents, where small quantities of nitrous/fuel
                                                      activating dopaminergic neurons in the ventral
N2O in medicine is not fully known. However,                                                                 mixtures explode due to “water hammer-like”
                                                      tegmental area and nucleus accumbens,
it has been shown to directly modulate a broad                                                               effects (sometimes called “dieseling” – heating
                                                      presumably through antagonization of NMDA
range of ligand-gated ion channels, and this                                                                 caused by adiabatic compression of gases that
                                                      receptors localized in the system. This action
likely plays a major role in many of its effects.                                                            can reach decomposition temperatures). Some
                                                      has been implicated in its euphoric effects,
It moderately blocks NMDA and β2-subunit-                                                                    common building materials, such as stainless
                                                      and notably, appears to augment its analgesic
containing nACh channels; weakly inhibits                                                                    steel and aluminum, can act as fuels with
                                                      properties as well.
AMPA, kainate, GABAC and 5-HT3 receptors;                                                                    strong oxidizers such as nitrous oxide, as can
and slightly potentiates GABAA and glycine            However, it is remarkable that in mice, N2O            contaminants, which can ignite due to adiabatic
receptors. It has also been shown to activate         blocks amphetamine-induced and dopamine                compression.
two-pore-domain K+ channels. While N2O                release in the nucleus accumbens and behavioral
                                                                                                             There have also been accidents where nitrous
affects quite a few ion channels, its anesthetic,     sensitization, abolishes the conditioned place
                                                                                                             oxide decomposition in plumbing has led to the
hallucinogenic and euphoriant effects are likely      preference (CPP) of cocaine and morphine, and
                                                                                                             explosion of large tanks.
caused predominantly or fully via inhibition of       does not produce reinforcing (or aversive) effects
NMDAR-mediated currents. In addition to its           of its own. Studies on CPP of N2O in rats is           Biological
effects on ion channels, N2O may act to imitate       mixed, consisting of reinforcement, aversion and     Nitrous oxide inactivates the cobalamin form of
nitric oxide (NO) in the central nervous system       no change. In contrast, it is a positive reinforcer  vitamin B12 by oxidation. Symptoms of vitamin
as well, and this may relate to its analgesic and     in squirrel monkeys, and is well known as a          B12 deficiency, including sensory neuropathy
anxiolytic properties.                                drug of abuse in humans. These discrepancies                          and encephalopathy, can occur
                                                      in response to N2O may reflect specie variations                      within days or weeks of exposure
Anxiolytic effect                                     or methodological differences. It is noteworthy
In behavioral tests of anxiety, a low dose of N2O                                                                           to nitrous oxide anesthesia in
                                                      that in human clinical studies, N2O was found                         people with subclinical vitamin
is an effective anxiolytic, and this anti-anxiety
                                                      to produce mixed responses similarly to rats,                         B12 deficiency. Symptoms are
effect is associated with enhanced activity of
                                                      reflecting high subjective individual variability.                    treated with high doses of vitamin
GABAA receptors as it is partially reversed by
benzodiazepine receptor antagonists. Mirroring        neurotoxicity                                                         B12, but recovery can be slow and
this, animals that have developed tolerance to the    Similarly to other NMDA antagonists like                              incomplete. People with normal
anxiolytic effects of benzodiazepines are partially   ketamine, N2O has been demonstrated to                                vitamin B12 levels have stores to
tolerant to N2O. Indeed, in humans given 30           produce neurotoxicity in the form of Olney’s                          make the effects of nitrous oxide
percent N2O, benzodiazepine receptor antagonists      lesions (damage to the posterior cingulate and                        insignificant, unless exposure is
reduced the subjective reports of feeling “high,”     retrosplenial cortices) in rodents upon prolonged                     repeated and prolonged (nitrous
but did not alter psychomotor performance in          (e.g., several hours) exposure. However, it also                      oxide abuse). Vitamin B12 levels
human clinical studies.                               simultaneously exerts widespread neuroprotective                      should be checked in people with
                                                      effects via inhibiting glutamate-induced and it                       risk factors for vitamin B12
Analgesic and anti-nociceptive effect                 has been argued that on account of its very short    deficiency prior to using nitrous oxide anesthesia.
The analgesic effects of N2O are linked to the
                                                      duration under normal circumstances, N2O may
interaction between the endogenous opioid                                                                  A study of workers and several experimental
                                                      not share the neurotoxicity of other NMDA
system and the descending noradrenergic system.                                                            animal studies indicate that adverse reproductive
                                                      antagonists. Indeed, in rodents, short-term
When animals are given morphine chronically,
                                                      exposure results in only mild injury that is rapidly effects for pregnant females may also result from
they develop tolerance to its pain-killing effects,                                                        chronic exposure to nitrous oxide.
                                                      reversible, and permanent neuronal death only
and this also renders the animals tolerant to
                                                      occurs after constant and sustained exposure.        Flammability
the analgesic effects of N2O. Administration of
antibodies that bind and block the activity of        safety                                               Nitrous oxide is a non-flammable gas at room
some endogenous opioids (not β-endorphin) also        The major safety hazards of nitrous oxide come       temperature.
block the anti-nociceptive effects of N2O. Drugs      from the fact that it is a compressed liquefied gas,   The National Fire Protection Association has not
that inhibit the breakdown of endogenous opioids      an asphyxiation risk and a dissociative anesthetic.    assigned a flammability rating to nitrous oxide:
also potentiate the anti-nociceptive effects of       Exposure to nitrous oxide causes short-term             Flash point: Not applicable.
N2O. Several experiments have shown that opioid       decreases in mental performance, audiovisual            Autoignition temperature: Not applicable.
receptor antagonists applied directly to the brain    ability and manual dexterity. Long-term exposure        Flammable limits in air: Not applicable.
block the anti-nociceptive effects of N2O, but        can cause vitamin B12 deficiency, numbness,             Extinguishant: For small fires, use dry
these drugs have no effect when injected into the     reproductive side effects and other problems.              chemical or carbon dioxide. Use water spray,
spinal cord.                                                                                                     fog or standard foam to fight large fires
                                                      The National Institute for Occupational Safety
Conversely, α2-adrenoceptor antagonists block                                                                    involving nitrous oxide.
                                                      and Health recommends that workers’ exposure
the anti-nociceptive effects of N2O when              to nitrous oxide should be controlled during

Elite CME                                                                                                                                               Page 29
Fires involving nitrous oxide should be fought         standards. Nitrous oxide is entirely legal to         can produce adverse health effects in the
upwind from the maximum distance possible.             possess and inhale in the United Kingdom,             offspring.
Keep unnecessary people away; isolate the              although supplying it to others to inhale,
                                                                                                             Several studies of workers have shown that
hazard area and deny entry. Isolate the area for       especially minors, is more likely to end up with a
                                                                                                             occupational exposure to N2O causes adverse
½-mile in all directions if a tank, rail car or tank   prosecution under the Medicines Act.
                                                                                                             effects such as reduced fertility, spontaneous
truck is involved in the fire. For a massive fire
                                                       In New Zealand, the Ministry of Health has            abortions and neurologic, renal and liver disease.
in a cargo area, use unmanned hose holders or
                                                       warned that nitrous oxide is a prescription           A recent study reported that female dental
monitor nozzles; if this is impossible, withdraw
                                                       medicine, and its sale or possession without a        assistants exposed to unscavenged N2O for five
from the area and let the fire burn. Emergency
                                                       prescription is an offense under the Medicines        or more hours per week had a significant risk
personnel should stay out of low areas and
                                                       Act. This statement would seemingly prohibit all      of reduced fertility compared with unexposed
ventilate closed spaces before entering. Vapors
                                                       non-medicinal uses of the chemical, though it is      female dental assistants. The exposed assistants
are an explosion hazard indoors, outdoors or in
                                                       implied that only recreational use will be legally    had a 59 percent decrease in probability of
sewers. Containers of nitrous oxide may explode
                                                       targeted.                                             conception for any given menstrual cycle
in the heat of the fire and should be moved from
                                                                                                             compared with the unexposed assistants. For
the fire area if it is possible to do so safely. If    In India, for general anesthesia purposes, nitrous
                                                                                                             dental assistants who used scavenging systems
this is not possible, cool fire-exposed containers     oxide is available as nitrous oxide IP. India’s
                                                                                                             during N2O administration, the probability
from the sides with water until well after the fire    gas cylinder rules (1985) permit the transfer of
                                                                                                             of conception was not significantly different
is out. Stay away from the ends of containers.         gas from one cylinder to another for breathing
                                                                                                             from that of the unexposed assistants. Because
Firefighters should wear a full set of protective      purposes. This law benefits remote hospitals,
                                                                                                             environmental exposures were not measured
clothing and self-contained breathing apparatus        which would otherwise suffer because of
                                                                                                             during these epidemiologic studies, no dose-
when fighting fires involving nitrous oxide.           India’s geographic immensity. Nitrous oxide
                                                                                                             effect relationship could be established.
                                                       IP is transferred from bulk cylinders (17,000
Environmental                                          liters capacity gas) to smaller pin-indexed           Exposure to high concentrations of waste
Nitrous oxide is a greenhouse gas, accounting          valve cylinders (1,800 liters of gas), which          anesthetic gases – even for a short time – may
for about 6 percent of the heating effect of           are then connected to the yoke assembly of            cause the following health effects:
greenhouse gases in the atmosphere. According to       Boyle’s machines. Because India’s Food and             Headache.
2006 data from the United States Environmental         Drug Authority (FDA-India) rules state that            Irritability.
Protection Agency, industrial sources make             transferring a drug from one container to another      Fatigue.
up only about 20 percent of all anthropogenic          (refilling) is equivalent to manufacturing,            Nausea.
sources, and include the production of nylon and       anyone found doing so must possess a drug-             Drowsiness.
the burning of fossil fuel in internal combustion      manufacturing license.                                 Difficulties with judgment and coordination.
engines. Human activity is thought to account                                                                 Liver and kidney disease.
for 30 percent; tropical soils and oceanic release     nitrous oxide in dental operatories
account for 70 percent. However, a 2008 study          The Engineering Control Technology Branch             Workers exposed
by Nobel Laureate Paul Crutzen suggests that the       (ECTB) of the Division of Physical Sciences and       In 1983, the American Dental Association (ADA)
amount of nitrous oxide release attributable to        Engineering studies the aspects of health hazard      reported that 35 percent of all dentists used N2O
agricultural nitrate fertilizers has been seriously    prevention and control in the workplace. Nitrous      to control pain and anxiety in their patients [ADA
underestimated, most of which would presumably         oxide (N2O) mixed with oxygen has been used           1983]. The ADA 1991 Survey of Dental Practice
come under soil and oceanic release in the             in dentistry as an analgesic and as a sedative for    indicated that 58 percent of dentists reported
Environmental Protection Agency data. Nitrous          more than 100 years. Today, more than 424,000         having N2O anesthetic equipment, and 64 percent
oxide also causes ozone depletion. A recent study      workers who practice dentistry (such as dentists,     of those practitioners also reported having a
suggests that N2O emission currently is the single     dental assistants and dental hygienists) in the       scavenging system. The percentage of pediatric
most important ozone-depleting substance (ODS)         United States are potentially exposed to N2O.         dentists using N2O increased from 65 percent in
emission and is expected to remain the largest                                                               1980 to 88 percent in 1988.
                                                       In a technical report published in 1977, the
throughout the 21st century.                           National Institute for Occupational Safety and        occupational exposure limits
                                                       Health recommended controlling exposure limits        The Occupational Safety and Health
                                                       of nitrous oxide waste to 25 parts per million        Administration (OSHA) does not currently have a
In the United States, possession of nitrous oxide
                                                       parts (ppm) of air during dental surgery. The         standard for N2O.
is legal under federal law and is not subject to
DEA purview. It is, however, regulated by the          report presented methods for limiting the waste       The NIOSH recommended exposure
Food and Drug Administration under the Food            during administration, based on the technical         limit (REL) for N2O is 25 ppm as a time-
Drug and Cosmetics Act; prosecution is possible        feasibility of existing controls. Since publication   weighted average (TWA) during the period
under its “misbranding” clauses, prohibiting           of this technical report, data collected by           of anesthetic administration [NIOSH 1977b].
the sale or distribution of nitrous oxide for the      NIOSH have shown occupational exposures as            This REL is intended to prevent decreases in
purpose of human consumption.                          high as 300 ppm in hospital operating rooms           mental performance, audiovisual ability and
                                                       and exposures higher than 1,000 ppm in dental         manual dexterity during exposures to N2O. A
Many states have laws regulating the possession,       operatories equipped with scavenging systems          recommended exposure limit to prevent adverse
sale and distribution of nitrous oxide. Such laws      (properly operating scavenging systems have           reproductive effects cannot be established until
usually ban distribution to minors or limit the        been shown to reduce N2O concentrations by            more data are available.
amount of nitrous oxide that may be sold without       more than 70 percent). The scavenging systems
special license.                                                                                      The American Conference of Governmental
                                                       use local exhaust ventilation to collect waste
                                                                                                      Industrial Hygienists’ (ACGIH) threshold limit
In the state of California, possession for             gases from anesthetic breathing systems and
                                                                                                      value (TLV) for N2O is 50 ppm as an eight-hour
recreational use is prohibited and qualifies as a      remove them from the workplace.
                                                                                                      time-weighted average [ACGIH 1993]. The 1991
misdemeanor.                                           Effects of exposure to high concentrations Documentation of the Threshold Limit Values
In some countries, it is illegal to have nitrous       Animal studies have shown adverse reproductive and Biological Exposure Indices states that
oxide systems plumbed into an engine’s intake          effects in female rats exposed to airborne     “control to this level should prevent embryo-fetal
manifold. These laws are ostensibly used to            concentrations of N2O. Data from these studies toxicity in humans and significant decrements
prevent street racing and to meet emission             indicate that exposure to N2O during gestation in human psychomotor and cognitive functions

Page 30                                                                                                                                               Elite CME
or other adverse health effects in exposed            is minimal, evaluations should be conducted           recommendations in a 1994 NIOSH alert should
personnel” [ACGIH 1991].                              every three to five years or as frequently as         therefore be followed to minimize worker
                                                      recommended by an experienced occupational            exposures.
Medical surveillance
                                                      health physician. Additional examinations may
OSHA is currently developing requirements for                                                               Recommendations
                                                      be necessary if a worker develops symptoms
medical surveillance. When these requirements                                                               Engineering controls, work practices and
                                                      attributable to nitrous oxide exposure. The
are promulgated, readers should refer to them for                                                           respirators (when necessary) should be used
                                                      interviews, examinations and medical screening
additional information and to determine whether                                                             to minimize the exposure of workers to N2O.
                                                      tests should focus on identifying the adverse
employers whose employees are exposed to                                                                    Employers should ensure that their workers are
                                                      effects of nitrous oxide on the respiratory,
nitrous oxide are required to implement medical                                                             adequately protected from N2O exposure by
                                                      reproductive, central nervous or hematological
surveillance procedures.                                                                                    taking the following steps:
                                                      systems. Current health status should be
                                                                                                             Monitor airborne concentrations of N2O.
Medical screening                                     compared with the baseline health status of the
                                                                                                             Implement appropriate engineering controls,
Workers who may be exposed to chemical                individual worker or with expected values for a
                                                                                                                work practices and maintenance procedures.
hazards should be monitored in a systematic           suitable reference population.
                                                                                                             Institute a worker education program that:
program of medical surveillance that is intended
                                                      Termination medical evaluations                           Š Describes standard operating procedures
to prevent occupational injury and disease. The
                                                      The medical, environmental and occupational                   for all tasks that may expose workers to
program should include education of employers
                                                      history interviews; the physical examination; and             N2O.
and workers about work-related hazards, early
                                                      selected physiologic or laboratory tests that were        Š Informs workers about proper work
detection of adverse health effects and referral
                                                      conducted at the time of placement should be                  practices, controls, equipment and
of workers for diagnosis and treatment. The
                                                      repeated at the time of job transfer or termination           protective gear that should be used when
occurrence of disease or other work-related
                                                      to determine the worker’s medical status at the               working with N2O.
adverse health effects should prompt immediate
                                                      end of his or her employment. Any changes in           Use the guidelines in the following section to
evaluation of primary preventive measures (e.g.,
                                                      the worker’s health status should be compared             minimize worker exposures to N2O.
industrial hygiene monitoring, engineering
                                                      with those expected for a suitable reference
controls, and personal protective equipment).                                                               guidelines for minimizing worker
A medical surveillance program is intended to                                                               exposures
supplement, not replace, such measures. To detect     Biological monitoring                                 Exposure monitoring
and control work-related health effects, medical      Biological monitoring involves sampling and        Exposure monitoring should be the first step in
evaluations should be performed (1) before job        analyzing body tissues or fluids to provide        developing work practices and worker education
placement, (2) periodically during the term of        an index of exposure to a toxic substance or       programs, because measurements of N2O are
employment, and (3) at the time of job transfer or    metabolite. No biological monitoring test          needed to determine the type and extent of
termination.                                          acceptable for routine use has yet been developed  controls that are necessary. Follow the guidelines
                                                      for nitrous oxide.                                 below to minimize worker exposures:
Preplacement medical evaluation
Before a worker is placed in a job with a             Workplace monitoring and measurement  Monitor for N2O when the anesthetic
potential for exposure to nitrous oxide, a licensed   Determination of a worker’s exposure to airborne       equipment is installed and every three months
health care professional should evaluate and          nitrous oxide can be made using one of the             thereafter. Include the following types of
document the worker’s baseline health status          following techniques:                                  monitoring:
with thorough medical, environmental and               A Landauer Passive Dosimeter badge, which            Š Leak testing of equipment.
occupational histories, a physical examination,            can be used for a minimum sampling duration       Š Monitoring of air in the worker’s
and physiologic and laboratory tests appropriate           of one hour (maximum duration 40 hours).              personal breathing zone.
for the anticipated occupational risks. These              Analysis is performed by the manufacturer         Š Environmental (room air) monitoring.
should concentrate on the function and integrity           of the badge as described in the OSHA          Prepare a written monitoring and
of the respiratory, reproductive, central                  Computerized Information System.                  maintenance plan for each facility that uses
nervous and hematological systems. Medical             An ambient air or bag sample with a                  N2O . This plan should be developed by
surveillance for respiratory disease should be             minimum collection volume of two                  knowledgeable persons who consider the
conducted using the principles and methods                 spectrophotometer cell volumes. Analysis is       equipment manufacturers’ recommendations,
recommended by the American Thoracic                       conducted using a long-path-length portable       frequency of use and other circumstances that
Society. A preplacement medical evaluation is              infrared spectrophotometer as described in        might affect the equipment.
recommended to assess medical conditions that              NIOSH Method No. 6600.                         Perform air monitoring by gasbag sampling
may be aggravated or may result in increased                                                                 or real-time sampling.
risk when a worker is exposed to nitrous oxide
                                                      Personal hygiene procedures                         When real-time sampling is conducted to
                                                      If liquid nitrous oxide contacts the skin, workers     obtain personal exposure data, attach the
at or below the prescribed exposure limit. The
                                                      should flush the affected areas immediately with       sampling train to the lapel of the worker
health care professional should consider the
                                                      tepid water to reduce the likelihood of frostbite.     on the side closest to the patient; N2O
probable frequency, intensity and duration of
exposure as well as the nature and degree of any      A large population of health care workers              concentrations in this location are most
applicable medical condition. Such conditions         is potentially exposed to N2O, and NIOSH               representative of those in the worker’s
(which should not be regarded as absolute             has documented cases in which exposures                breathing zone. Diffusive samplers (referred
contraindications to job placement) include           substantially exceed existing recommended              to as passive dosimeters) are commercially
a history and other findings consistent with          exposure limits. NIOSH has concluded that              available and may be useful as initial
diseases of the respiratory, reproductive, central    exposure to N2O causes decreases in mental             indicators of exposures.
nervous or hematological systems.                     performance, audiovisual ability and manual        Engineering controls and maintenance
                                                      dexterity. Data from animal studies demonstrate    procedures
Periodic medical evaluations                          that exposure to N2O may cause adverse             The following engineering controls and
Occupational health interviews and physical
                                                      reproductive effects. Studies of workers exposed   maintenance procedures have been shown to be
examinations should be performed at regular
                                                      to N2O have reported adverse health effects        feasible and effective in reducing exposure to
intervals during the employment period, as
                                                      such as reduced fertility, spontaneous abortion,   N2O during anesthetic administration.
mandated by any applicable federal, state or local
                                                      and neurological, renal, and liver disease. The
standard. Where no standard exists and the hazard
Elite CME                                                                                                                                            Page 31
Anesthetic delivery. Excessive exposure to N2O       Take the following steps to control N2O exposure          bags, hoses and clamps are in place before
may occur as a result of leaks from the anesthetic   from anesthetic scavenging systems:                       turning on the anesthetic machine.
delivery system during administration. The            Supply scavenging masks in a variety of sizes          Connect the scavenging mask properly to the
rubber and plastic components of the anesthetic          so that the mask always fits comfortably and          gas delivery hose and the vacuum system.
equipment are potential sources of N2O leakage           securely over the patient’s nose or face.            Do not turn on the machine delivering N2O
because they may be degraded by the N2O and           Use an automatic interlock system to assure             until:
the oxygen as well as by repeated sterilization.         that the N2O cannot be turned on unless the           Š The vacuum system scavenging unit is
                                                         scavenging system is also activated. N2O                  operating at the recommended flow rate
Take the following steps to control N2O exposure
                                                         should never be used without a properly                   of 45 L/min.
from anesthetic delivery systems:
                                                         operating scavenging system.                          Š The scavenging mask is secured over the
 Use connection ports with different-
                                                      Make sure that the scavenging system                        patient’s nose or face.
    diameter hoses for N2O and O2 to reduce the
                                                         exhaust rates (flow rates) are approximately         Fasten the mask according to the
    possibility of incorrectly connecting the gas
                                                         45 liters per minute (L/min) to minimize              manufacturer’s instructions to prevent leaks
    delivery and scavenging hoses.
                                                         leakage of N2O. Flow rates of less than 40 L/         around the mask during gas delivery.
 Check all rubber hoses, connections, tubing
                                                         min may result in significant leakage around         Do not fill the breathing bag to capacity with
    and breathing bags daily and replace them
                                                         the mask. Monitor the flow rate with a flow           N2O; an overinflated bag can cause excessive
    when damaged or when recommended by the
                                                         meter that is:                                        leakage from the scavenging mask. The
                                                         Š Validated to measure airflow within 5               breathing bag should collapse and expand as
 Following visual inspection, perform leak
                                                              percent of actual airflow.                       the patient breaths. This bag activity shows
    testing of the equipment and connections by
                                                         Š Permanently connected to the scavenging             that the proper amounts of N2O and air are
    using a soap solution to check for bubbles
                                                              system vacuum line.                              being delivered to the patient.
    at high-pressure connections. For a more
                                                         Š Positioned so that it is always visible to         Flush the system of N2O after surgery by
    thorough inspection of all connectors, use a
                                                              the operator.                                    administering oxygen to the patient through
    portable infrared spectrophotometer (such
                                                      Maintain the flow meter by cleaning                     the anesthetic equipment for at least five
    as a Miran 1A or 1B) calibrated for N2O
                                                         and recalibrating it according to the                 minutes before disconnecting the gas delivery
                                                         manufacturer’s recommendations.                       system.
 Check both high- and low-pressure
                                                      Use scavenging vacuum pumps that are                   Encourage patients to minimize talking
    connections (such as O-rings) regularly,
                                                         powerful enough to maintain a scavenging              and mouth-breathing during dental surgery.
    as they may become worn; replace them
                                                         flow rate of at least 45 L/min at each nasal          When mouth-breathing is apparent, avoid
    periodically, according to the manufacturer’s
                                                         mask, regardless of the number of scavenging          the patient’s breathing zone to the extent
                                                         units in use at one time.                             possible.
 Evaluate the N2O and oxygen mixing
                                                      Vent N2O from all scavenging vacuum pumps
    system for leaks when it is first installed                                                            Respiratory protection
                                                         to the outside of the building away from
    and periodically thereafter, according to the                                                          Workers should wear respiratory protection when
                                                         fresh air intakes, windows or walkways.
    manufacturer’s recommendations.                                                                        N2O concentrations are not consistently below
                                                         Scavenging system exhaust should not be
 Ensure that gas cylinders are safely handled,                                                            25 ppm; however, practical considerations may
                                                         vented into a recirculating ventilation system.
    used and stored as specified by the National                                                           prevent them from wearing such protection.
    Research Council and as required by OSHA         Room ventilation. Take the following steps to         Therefore, it is essential that employers use
    Federal Code Rule Title 29, 1910.101.            assure that the ventilation system effectively        the engineering controls and work practices
    Š Sec. 1910.101 Compressed gases                 removes waste N2O:                                    described in a 1994 NIOSH alert to reduce N2O
         (general requirements).                      If concentrations of N2O are above 25 ppm in        concentrations below 25 ppm.
    Š (a) Inspection of compressed gas                   work areas, increase the airflow into the room    When N2O concentrations are not consistently
         cylinders. Each employer shall determine        or increase the percentage of outside air to      below 25 ppm, workers should take the following
         that compressed gas cylinders under             allow for more air mixing and further dilution    steps to protect themselves:
         his control are in a safe condition to          of the anesthetic gas. Maintain a balanced air     Wear air-supplied respirators. Air-purifying
         the extent that this can be determined          supply and exhaust system so that N2O does            respirators (that is, respirators that remove
         by visual inspection. Visual and other          not contaminate adjacent areas.                       N2O from the air rather than supply air from
         inspections shall be conducted as            If concentrations of N2O are still above 25             a clean source) should not be used because
         prescribed in the Hazardous Materials           ppm, use supplementary local ventilation              respirator filters do not efficiently remove
         Regulations of the Department of                in conjunction with a scavenging system to            N2O.
         Transportation (49 CFR parts 171-179            reduce N2O exposure in the operatory. The          As specified by the NIOSH respirator
         and 14 CFR part 103). Where those               effectiveness of this ventilation depends             standards, the minimum level of protection
         regulations are not applicable, visual          on its location with respect to the patient           for an air-supplied respirator is provided by a
         and other inspections shall be conducted        and the airflow rates. Do not work between            half-mask respirator operated in the demand
         in accordance with Compressed Gas               the patient and the exhaust duct, where               or continuous-flow mode. More protective
         Association Pamphlets C-6-1968 and              contaminated air would be drawn through the           air-supplied respirators are described in the
         C-8-1962, which is incorporated by              worker’s breathing zone.                              NIOSH respirator decision logic.
         reference as specified in Sec. 1910.6.       Dilute N2O and remove contaminated air               When respirators are used, the employer
                                                         from the work area by placing fresh-air vents         must establish a comprehensive respiratory
Scavenging systems. Control of N2O at the
                                                         in the ceiling; direct the supply of fresh air        protection program as outlined in the NIOSH
scavenging mask is the next priority after control
                                                         toward the floor and the operating area. Place        Guide to Industrial Respiratory Protection
of N2O leakage from the anesthetic equipment.
                                                         exhaust-air vents at or near the floor.               [NIOSH 1987a] and as required by the
Leakage from the scavenging mask can be one
of the most significant sources of N2O exposure      Work practices                                            OSHA respiratory protection standard [29
because the breathing zone of a dentist or           Use the following work practices to control N2O           CFR 1910.134]. Important elements of this
dental assistant is within inches of the mask.       exposures:                                                standard are:
NIOSH research has reported breathing-zone            Inspect the anesthetic delivery systems and             Š An evaluation of the worker’s ability
concentrations of N2O above 1,000 ppm.                  all connections before starting anesthetic                  to perform the work while wearing a
                                                        gas administration. Make sure that breathing                respirator.
Page 32                                                                                                                                             Elite CME
    Š   Regular training of personnel.               Emergency planning requirements                       been approved by NIOSH and the Mine Safety
    Š   Periodic environmental monitoring.           Nitrous oxide is not subject to EPA emergency         and Health Administration (MSHA).
    Š   Respirator fit testing.                      planning requirements under the Superfund
        Maintenance, inspection, cleaning and
                                                                                                           Respiratory protection program
    Š                                                Amendments and Reauthorization Act (SARA)
                                                                                                           Employers should institute a complete respiratory
        storage.                                     (Title III) in 42 CFR 11022.
                                                                                                           protection program that, at a minimum, complies
    Š Selection of proper NIOSH-approved
                                                     Reportable quantity requirements for                  with the requirements of OSHA’s Respiratory
                                                     hazardous releases                                    Protection Standard [29 CFR 1910.134]. Such
   The respiratory protection program should be
                                                     Employers are not required by the emergency           a program must include respirator selection, an
    evaluated regularly by the employer.
                                                     release notification provisions in 40 CFR Part        evaluation of the worker’s ability to perform
signs and symptoms of exposure                       355.40 to notify the National Response Center of      the work while wearing a respirator, the regular
   Acute exposure: The signs and symptoms           an accidental release of nitrous oxide; there is no   training of personnel, respirator fit testing,
    of acute exposure to nitrous oxide include       reportable quantity for this substance.               periodic workplace monitoring, and regular
    dizziness, difficult breathing, headache,                                                              respirator maintenance, inspection and cleaning.
    nausea, fatigue and irritability. Acute          Community right-to-know requirements                  The implementation of an adequate respiratory
    exposure to nitrous oxide concentrations of      Employers are not required by EPA in 40 CFR
                                                                                                           protection program (including selection of the
    400,000 to 800,000 ppm may cause loss of         Part 372.30 to submit a Toxic Chemical Release
                                                                                                           correct respirator) requires that a knowledgeable
    consciousness.                                   Inventory form (Form R) to EPA reporting the
                                                                                                           person be in charge of the program and that
    Chronic exposure: The signs or symptoms          amount of nitrous oxide emitted or released from
                                                                                                          the program be evaluated regularly. For
    of chronic overexposure to nitrous oxide         their facility annually.
                                                                                                           additional information on the selection and use
    may include tingling, numbness, difficulty       Hazardous waste management                            of respirators and on the medical screening of
    in concentrating, interference with gait, and    requirements                                          respirator users, consult the latest edition of the
    reproductive effects.                            EPA considers a waste to be hazardous if it           NIOSH Respirator Decision Logic [NIOSH
storage                                              exhibits any of the following characteristics:        1987b] and the NIOSH Guide to Industrial
Nitrous oxide should be stored in a cool, dry,       ignitability, corrosivity, reactivity or toxicity     Respiratory Protection [NIOSH 1987a].
well-ventilated area in tightly sealed containers    as defined in 40 CFR 261.21-261.24. Under
                                                                                                           Personal protective equipment
that are labeled in accordance with OSHA’s           the Resource Conservation and Recovery
                                                                                                           Workers should use appropriate personal
Hazard Communication Standard [29 Code               Act (RCRA) [40 USC 6901 et seq.], EPA
                                                                                                           protective clothing and equipment that must be
of Federal Regulations (CFR)1910.1200].              has specifically listed many chemical wastes
                                                                                                           carefully selected, used and maintained to be
Containers of nitrous oxide should be protected      as hazardous. Although nitrous oxide is not
                                                                                                           effective in preventing skin contact with liquid
from physical damage and should be stored            specifically listed as a hazardous waste under
                                                                                                           nitrous oxide. The selection of the appropriate
separately from cylinders containing oxygen.         RCRA, EPA requires employers to treat waste as
                                                                                                           personal protective equipment (PPE) (e.g.,
Nitrous oxide should also be stored separately       hazardous if it exhibits any of the characteristics
                                                                                                           gloves, sleeves, encapsulating suits) should be
from aluminum, boron, hydrazine, lithium             discussed above. Providing detailed information
                                                                                                           based on the extent of the worker’s potential
hydride, phenyllithium, phosphine, sodium,           about the removal and disposal of specific
                                                                                                           exposure to liquid nitrous oxide and the PPE
tungsten carbide, hydrogen, hydrogen sulfide,        chemicals is beyond the scope of this guideline.
                                                                                                           material’s ability to protect workers from
organic peroxides, ammonia and carbon                The U.S. Department of Transportation, EPA, and
                                                                                                           frostbite. There are no published reports on the
monoxide.                                            state and local regulations should be followed
                                                                                                           resistance of various materials to permeation by
                                                     to ensure that removal, transport and disposal
spills and leaks                                                                                           liquid nitrous oxide.
                                                     of this substance are conducted in accordance
In the event of a spill or leak involving nitrous    with existing regulations. To be certain that         To evaluate the use of PPE materials with liquid
oxide (liquid or gas), persons not wearing           chemical waste disposal meets EPA regulatory          nitrous oxide, users should consult the best
protective equipment and clothing should be          requirements, employers should address any            available performance data and manufacturers’
restricted from contaminated areas until cleanup     questions to the RCRA hotline at (703) 412-           recommendations. Significant differences have
has been completed. The following steps should       9810 (in the Washington, D.C. area) or toll-free      been demonstrated in the chemical resistance of
be undertaken following a spill or leak:             at 800-424-9346 (outside Washington, D.C.).           generically similar PPE materials (e.g., butyl)
 Do not touch the spilled material; stop the        In addition, relevant state and local authorities     produced by different manufacturers. In addition,
    leak if it is possible to do so without risk.    should be contacted for information on any            the chemical resistance of a mixture may be
 Use water spray to protect persons attempting      requirements they may have for the waste              significantly different from that of any of its neat
    to stop the leak.                                removal and disposal of this substance.               components.
 Notify safety personnel of large spills or
    leaks.                                           Respiratory protection                                Any chemical-resistant clothing that is used
 Minimize all sources of ignition because a         Conditions for respirator use                         should be periodically evaluated to determine its
    fire may cause nitrous oxide to accelerate       Good industrial hygiene practice requires that        effectiveness in preventing dermal contact. Safety
    the burning of other combustibles; keep          engineering controls be used where feasible to        showers and eye wash stations should be located
    combustible materials (wood, paper, oil, etc.)   reduce workplace concentrations of hazardous          close to operations that involve nitrous oxide.
    away from the spilled material.                  materials to the prescribed exposure limit.           Splash-proof chemical safety goggles or face
 Isolate the area until the gas has dispersed.      However, some situations may require the use          shields (20 to 30 cm long, minimum) should be
                                                     of respirators to control exposure. Respirators       worn during any operation in which a solvent,
special requirements
                                                     must be worn if the ambient concentration of          caustic or other toxic substance may be splashed
United States Environmental Protection Agency
                                                     nitrous oxide exceeds prescribed exposure limits.     into the eyes.
(EPA) requirements for emergency planning,
                                                     Respirators may be used (1) before engineering
reportable quantities of hazardous releases,                                                               In addition to the possible need for wearing
                                                     controls have been installed, (2) during work
community right-to-know and hazardous waste                                                                protective outer apparel (e.g., aprons,
                                                     operations such as maintenance or repair
management may change over time. Users are                                                                 encapsulating suits), workers should wear work
                                                     activities that involve unknown exposures, (3)
therefore advised to determine periodically                                                                uniforms, coveralls or similar full-body coverings
                                                     during operations that require entry into tanks
whether new information is available.                                                                      that are laundered each day. Employers should
                                                     or closed vessels, and (4) during emergencies.
                                                     Workers should only use respirators that have         provide lockers or other closed areas to store

Elite CME                                                                                                                                               Page 33
work and street clothing separately. Employers           of protection because of variations in the          anesthetic gases and vapors to the patient via a
should collect work clothing at the end of               manufacturing processes or in the raw               breathing circuit. The anesthesia machine also
each work shift and provide for its laundering.          materials and additives used in processing.         provides a working surface for placement of
Laundry personnel should be informed about              Professional judgment must be used in               drugs and devices for immediate access and
the potential hazards of handling contaminated           determining the type of respiratory protection      drawers for storage of small equipment, drugs,
clothing and instructed about measures to                to be worn. For example, where spills of            supplies and equipment instruction manuals.
minimize their health risk.                              halogenated anesthetic agents are small,            Finally, the machine serves as a frame and source
                                                         exposure time brief and sufficient ventilation      of pneumatic and electric power for various
Protective clothing should be kept free of oil and
                                                         present, NIOSH-approved chemical cartridge          accessories such as a ventilator, and monitors
grease and should be inspected and maintained
                                                         respirators for organic vapors should provide       that observe or record vital patient functions
regularly to preserve its effectiveness.
                                                         adequate protection during cleanup activities.      or that are critical to the safe administration of
Protective clothing may interfere with the body’s       Where large spills occur and there is               anesthesia.
heat dissipation, especially during hot weather          insufficient ventilation to adequately reduce
or during work in hot or poorly ventilated work
                                                                                                             Gas flow in the anesthesia machine and
                                                         airborne levels of the halogenated agent,
environments.                                            respirators designed for increased respiratory      breathing system
                                                         protection should be used. The following            The internal piping of a basic two-gas anesthesia
More on personal protective equipment
                                                         respirators, to be selected for large spills, are   machine is shown in Figure 1(located at end of
   Personal protective equipment should not be
                                                         ranked in order from minimum to maximum             this chapter). The machine has many connections
    used as a substitute for engineering, work
                                                         respiratory protection:                             and potential sites for leaks. Both oxygen and
    practice and/or administrative controls in
                                                         Š Any type C supplied-air respirator with a         N2O may be supplied from two sources (Figure 2
    anesthetizing locations and post anesthesia
                                                             full facepiece, helmet or hood operated in      - located at end of this chapter): a pipeline supply
    care units (PACUs). In fact, exposure to
                                                             continuous-flow mode.                           source (central piping system from bulk storage)
    waste gases is not effectively reduced by
                                                         Š Any type C supplied-air respirator with           and a compressed gas cylinder supply source.
    gloves, goggles and surgical masks. A
                                                             a full facepiece operated in pressure-          In hospitals, the pipeline supply source is the
    negative-pressure, high-efficiency particulate
                                                             demand or other positive-pressure mode.         primary gas source for the anesthesia machine.
    air (HEPA) filter used for infection control
                                                         Š Any self-contained breathing apparatus            Pipeline-supplied gases are delivered through
    is also not appropriate to protect workers
                                                             with a full facepiece operated in pressure-     wall outlets at a pressure of 50-55 psig through
    from waste gases. Air-supplied respirators
                                                             demand or other positive-pressure mode.         diameter indexed safety system (DISS) fittings
    with self-contained air source are ideal for
                                                                                                             or through quick-connect couplings that are
    eliminating exposure but are not a practical
                                                     Workplace exposures                                     gas-specific within each manufacturer’s patented
                                                     Workplace exposures to anesthetic gases occur           system.
   During cleanup and containment of spills of
                                                     in hospital-based and stand-alone operating
    liquid anesthetic agents, personal protective                                                            Because pipeline systems can fail and because
                                                     rooms, recovery rooms, dental operatories and
    equipment should be used in conjunction                                                                  the machines may be used in locations where
                                                     veterinary facilities. Engineering, work practice
    with engineering, work practice and/                                                                     piped gases are not available, anesthesia
                                                     and administrative controls that help reduce
    or administrative controls to provide for                                                                machines are fitted with reserve cylinders of
                                                     these exposures in all anesthetizing locations
    employee safety and health. Gloves, goggles,                                                             oxygen and N2O. The oxygen cylinder source is
                                                     are identified and discussed. Sources of leaks
    face shields and chemical protective clothing                                                            regulated from approximately 2,200 psig in the
                                                     in anesthesia equipment systems, components,
    (CPC) are recommended to ensure worker                                                                   tanks to approximately 45 psig in the machine
                                                     and accessories are identified, and appropriate
    protection. Respirators, where needed,                                                                   high-pressure system, and the N2O cylinder
                                                     methods are described that limit excessive leaks.
    should be selected based on the anticipated                                                              source is regulated from 745 psig in the tanks
    contamination level.                             Inhaled anesthetic agents include two                   to approximately 45 psig in the machine high-
   When selecting gloves and chemical               different classes of chemicals: nitrous oxide           pressure system.
    protective clothing, some of the factors to      and halogenated agents. Halogenated agents
                                                                                                             Figure 1
    be considered include material chemical          currently in use include halothane (Fluothane®),
                                                                                                             The flow arrangement of a basic two-gas
    resistance, physical strength and durability,    enflurane (Ethrane®), isoflurane (Forane®),
                                                                                                             anesthesia machine. A, The fail-safe valve in
    and overall product integrity. Permeation,       desflurane (Suprane®), and sevoflurane (Ultane®).
                                                                                                             Ohmeda machines is termed a pressure sensor
    penetration and degradation data should          Methoxyflurane (Penthrane®), once in general
                                                                                                             shut-off valve; in Dräger machines it is the
    be consulted if available. Among the most        use, is now only infrequently used, primarily in
                                                                                                             oxygen failure protection device (OFPD). B,
    effective types of gloves and body protection    veterinary procedures. At present, OSHA has
    are those made from Viton®, neoprene             no permissible exposure limits regulating these         Second-stage oxygen pressure regulator is used
    and nitrile. Polyvinyl alcohol (PVA) is also     agents.                                                 in Ohmeda (but not Dräger Narkomed) machines.
    effective, but it should not be exposed to                                                               C, Second-stage nitrous oxide pressure regulator
                                                     The basic anesthesia machine
    water or aqueous solutions.                                                                              is used in Ohmeda Modulus machines having the
                                                     An anesthesia machine is an assembly of various
   When the gloves and the CPC being used                                                                   Link 25 Proportion Limiting System; not used in
                                                     components and devices that include medical
    have not been tested under the expected                                                                  Dräger machines. D, Pressure relief valve used
                                                     gas cylinders in machine hanger yokes, pressure
    conditions, they may fail to provide adequate                                                            in certain Ohmeda mchines; not used in Dräger
                                                     regulating and measuring devices, valves, flow
    protection. In this situation, the wearer                                                                machines. E, Outlet check valve used in Ohmeda
                                                     controllers, flow meters, vaporizers, CO2 absorber
    should observe the gloves and the chemical                                                               machines except Modulus II Plus and Modulus
                                                     canisters, and breathing circuit assembly. The
    protective clothing during use and treat any                                                             CD models; not used in Dräger machines. The
                                                     basic two-gas anesthesia machine has more than
    noticeable change (e.g., color, stiffness,                                                               oxygen take-off for the anesthesia ventilator
                                                     700 individual components.
    chemical odor inside) as a failure until                                                                 driving gas circuit is downstream of the main on/
    proved otherwise by testing. If the work         The anesthesia machine is a basic tool of the           off switch in Dräger machines, as shown here. In
    must continue, new CPC should be worn for        anesthesiologist/anesthetist and serves as the          Ohmeda machines, the take-off is upstream of the
    a shorter exposure time, or be of a different    primary work station. It allows the anesthesia          main on/off switch. (Adapted from Check-out: a
    generic material. The same thickness of          provider to select and mix measured flows of            guide for preoperative inspection of an anesthesia
    a generic material such as neoprene or           gases, to vaporize controlled amounts of liquid         machine, ASA, 1987. Reproduced by permission
    nitrile supplied by different manufacturers      anesthetic agents, and thereby to administer            of the American Society of Anesthesiologists,
    may provide significantly different levels       safely controlled concentrations of oxygen and          520 N. Northwest Highway, Park Ridge, Ill.)
Page 34                                                                                                                                                Elite CME
Figure 2                                              a face mask, tracheal tube, laryngeal mask airway      system leaks may occur from the connections and
The supply of nitrous oxide and oxygen may            (LMA) or other airway management device.               components anywhere between the anesthesia gas
come from two sources: the wall (pipeline)                                                                   flow control valves and the airway. This leakage
                                                      Once inside the breathing system, the mixture of
supply and the reserve cylinder supply.                                                                      may occur from loose-fitting connections,
                                                      gases and vapors flows to the breathing system’s
(Reproduced by permission of Datex·Ohmeda,                                                                   defective and worn seals and gaskets, worn or
                                                      inspiratory unidirectional valve, then on toward
Madison, Wisconsin). Compressed gas cylinders                                                                defective breathing bags, hoses, and tubing,
                                                      the patient. Exhaled gases pass through the
of oxygen, N2O, and other medical gases are                                                                  loosely assembled or deformed slip joints and
                                                      expiratory unidirectional valve and enter the
attached to the anesthesia machine through                                                                   threaded connections, and the moisture drainage
                                                      reservoir bag. When the bag is full, excess gas
the hanger yoke assembly. Each hanger yoke                                                                   port of the CO2 absorber, which may be in the
                                                      flows through the APL (or pop-off) valve and
is equipped with the pin index safety system,                                                                “open” position.
                                                      into the scavenging system that removes the
a safeguard introduced to eliminate cylinder
                                                      waste gases. On the next inspiration, gas from the     Low-pressure system leaks also may occur at the
interchanging and the possibility of accidentally
                                                      reservoir bag passes through the carbon dioxide        gas analysis sensor (i.e., circuit oxygen analyzer)
placing the incorrect gas tank in a yoke designed
                                                      absorber prior to joining the fresh gas from the       and gas sampling site(s), face mask, the tracheal
for another gas tank.
                                                      machine on its way to the patient. The general         tube (especially in pediatric patients where a leak
Figure 3 (located at end of this chapter) shows       use of fresh gas flow rates into anesthetic systems    is required around the uncuffed tracheal tube),
the oxygen pathway through the flow meter, the        in excess of those required to compensate for          laryngeal mask airway (over the larynx), and
agent vaporizer, and the machine piping, and into     uptake, metabolism, leaks, or removal of exhaled       connection points for accessory devices such as
the breathing circuit. Oxygen from the wall outlet    carbon dioxide results in variable volumes of          a humidifier, temperature probe, or positive end-
or cylinder pressurizes the anesthesia delivery       anesthetic gases and vapors exiting the breathing      expiratory pressure (PEEP) valve. Inappropriate
system. Compressed oxygen provides the needed         system through the APL valve.                          installation of a calibrated vaporizer(s) or
energy for a pneumatically powered ventilator,                                                               misalignment of a vaporizer on its manifold can
                                                      When an anesthesia ventilator is used, the
if used, and it supplies the oxygen flush valve                                                              also contribute to anesthetic gas leakage.
                                                      ventilator bellows functionally replaces the
used to supplement oxygen flow to the breathing
                                                      circle system reservoir bag and becomes a part         Minute absorbent particles that may have been
circuit. Oxygen also “powers” an in-line
                                                      of the breathing circuit. The APL valve in the         spilled on the rubber seal around the absorber
pressure-sensor shutoff valve (“fail-safe” valve)
                                                      breathing circuit is either closed or excluded from    canister(s) may also prevent a gas-tight seal
for other gases to prevent their administration if
                                                      the circuit using a manual (“bag”)/automatic           when the canister(s) in the carbon dioxide
the O2 supply pressure in the O2 high-pressure
                                                      (ventilator) circuit selector switch. The ventilator   absorber is (are) reassembled). The exhaust from
system falls below a threshold value.
                                                      incorporates a pressure-relief valve that permits      a sidestream sampling respiratory gas analyzer
Oxygen and N2O flow from their supply sources         release of excess anesthetic gases from the circuit    and/or capnograph should also be connected
via their flow control valves, flow meters and        at end-exhalation. These gases should also be          to the waste gas scavenging system because
common manifold to the concentration-calibrated       scavenged.                                             the analyzed gas sample may contain N2O or
vaporizer and then via the machine common gas                                                                halogenated vapors.
outlet to the breathing system. The high pressure
                                                      sources of leaks within the anesthesia
system of the anesthesia machine comprises            machine and breathing system                           Checking anesthesia machines
                                                       No anesthesia machine system is totally               Prior to induction of anesthesia, the anesthesia
those components from the compressed gas
                                                      leak-free (Emergency Care Research Institute           machine and its components/accessories should
supply source to the gas (O2 and N2O) flow
                                                      1991). Leakage may originate from both the             be made ready for use. All parts of the machine
control valves. The low pressure system of the
                                                      high-pressure and low-pressure systems of the          should be in good working order with all
anesthesia machine comprises those components
                                                      anesthesia or analgesia machine.                       accessory equipment and necessary supplies
downstream of the gas flow control valves.
                                                                                                             on hand. The waste gas disposal system should
Once the flows of oxygen, N2O, and other              The high-pressure system consists of all piping
                                                                                                             be connected, hoses visually inspected for
medical gases (if used) are turned on at their flow   and parts of the machine that receive gas at
                                                                                                             obstructions or kinks, and proper operation
control valves, the gas mixture flows into the        cylinder or pipeline supply pressure. It extends
                                                                                                             determined. Similarly, the anesthesia breathing
common manifold and through a concentration-          from the high-pressure gas supply (i.e., wall
                                                                                                             system should be tested to verify that it can
calibrated agent-specific vaporizer where a potent    supply or gas cylinder) to the flow control
                                                                                                             maintain positive pressure. Leaks should be
inhaled volatile anesthetic agent is added. The       valves. Leaks may occur from the high-pressure
                                                                                                             identified and corrected before the system is used.
mixture of gases and vaporized anesthetic agent       connections where the supply hose connects
                                                                                                             The ability of the anesthesia system to maintain
then exits the anesthesia machine low pressure        to the wall outlet or gas cylinder and where it
                                                                                                             constant pressure is tested not only for the safety
system through the common gas outlet and flows        connects to the machine inlet. Therefore, gas-
                                                                                                             of the patient dependent on a generated positive
to the breathing system.                              supply hoses should be positioned to prevent
                                                                                                             pressure ventilation but also to test for leaks and
                                                      strain on the fittings (ASTM Standard F1161-88;
The circle system shown in Figure 4 (located at                                                              escape of anesthetic gases, which may expose
                                                      Dorsch and Dorsch 1994) and constructed from
end of this chapter) is the breathing system most                                                            health-care personnel to waste anesthetic gases.
                                                      supply-hose materials designed for high-pressure
commonly used in operating rooms (ORs). It is         gas flow and minimal kinking (Bowie and                general workplace controls
so named because its components are arranged          Huffman 1985). High-pressure leakage may also          Occupational exposures can be controlled by
in a circular manner. The essential components        occur within the anesthesia machine itself. Other      the application of a number of well-known
of a circle breathing system (Figure 5, located       potential sources of leaks include quick-connect       principles, including engineering and work
at end of this chapter) include a site for inflow     fittings, cylinder valves, absent or worn gaskets,     practice controls, administrative controls,
of fresh gas (common [fresh] gas inlet), a carbon     missing or worn yoke plugs in a dual yoke              personal protective equipment and monitoring.
dioxide absorber canister (containing soda lime       assembly, and worn hoses.                              These principles may be applied at or near
or barium hydroxide lime) where exhaled carbon                                                               the hazard source, to the general workplace
dioxide is absorbed; a reservoir bag; inspiratory     The low-pressure system of the anesthesia
                                                      machine (in which the pressure is slightly above       environment, or at the point of occupational
and expiratory unidirectional valves; flexible                                                               exposure to individuals. Controls applied at
corrugated breathing tubing; an adjustable            atmospheric) consists of components downstream
                                                      of the flow-control valves. It therefore includes      the source of the hazard, including engineering
pressure-limiting (APL) or “pop-off” valve for                                                               and work practice controls, are generally the
venting excess gas; and a Y piece that connects to    the flow meter tubes, vaporizers, common
                                                      gas outlet and breathing circuit, (i.e., from the      preferred and most effective means of control.
                                                      common gas outlet to the patient). Low-pressure        In anesthetizing locations and PACUs, where
                                                                                                             employees are at risk of exposure to waste
Elite CME                                                                                                                                                Page 35
anesthetic gases, exposure may be controlled               The gas disposal assembly, which conveys          are thought to be more effective than passive
by some or all of the following: (1) effective              the excess gases to a point where they can        systems at reducing excess waste anesthetic gas
anesthetic gas scavenging systems that remove               be discharged safely into the atmosphere.         concentrations because leaks in the scavenging
excess anesthetic gas at the point of origin; (2)           Several methods in use include a                  system do not result in an outward loss of gas.
effective general or dilution ventilation; (3) good         nonrecirculating or recirculating ventilation
work practices on the part of the health care               system, a central vacuum system, a dedicated
                                                                                                              Passive systems
                                                                                                              HVAC systems used in health-care facilities are
workers, including the proper use of controls;              (single-purpose) waste gas exhaust system, a
                                                                                                              of two types: nonrecirculating and recirculating.
(4) proper maintenance of equipment to prevent              passive duct system and an adsorber.
                                                                                                              Nonrecirculating systems, also termed “one-pass”
leaks; and (5) periodic personnel exposure and
                                                        In general, a machine-specific interface must         or “single-pass” systems, take in fresh air from
environmental monitoring to determine the
                                                        be integrated with a facility’s system for gas        the outside and circulate filtered and conditioned
effectiveness of the overall waste anesthetic gas
                                                        removal. The interface permits excess gas to          air (i.e., controlled for temperature and humidity)
control program.
                                                        be collected in a reservoir (bag or canister) and     through the room. Whatever volumes of fresh
The following is a general discussion                   limits the pressure within the bag or canister.       air are introduced into the room are ultimately
of engineering controls, work practices,                A facility’s gas disposal system receives waste       exhausted to the outside. Waste anesthetic
administrative controls, and personal protective        anesthetic gases from the interface and should        gases can be efficiently disposed of via this
equipment that can reduce worker exposure               vent the waste gases outside the building and         nonrecirculating system.
to waste anesthetic gases. However, not every           away from any return air ducts or open windows,
                                                                                                              When a nonrecirculating ventilation system
control listed in this section may be feasible in all   thus preventing the return of the waste gases back
                                                                                                              serves through large-diameter tubing and
settings.                                               into the facility.
                                                                                                              terminating the tubing at the room’s ventilation
Engineering controls                                    Removal of excess anesthetic gases from the           exhaust as the disposal route for excess anesthetic
The collection and disposal of waste anesthetic         anesthesia circuit can be accomplished by either      gases, disposal involves directing the waste gases
gases in operating rooms and non-operating room         active or passive scavenging. When a vacuum or        grille. The sweeping effect of the air flowing into
settings is essential for reducing occupational         source of negative pressure is connected to the       the grille carries the waste gases away. Because
exposures. Engineering controls such as an              scavenging interface, the system is described as      all of the exhausted air is vented to the external
appropriate anesthetic gas scavenging system are        an active system. When a vacuum or negative           atmosphere in this type of system, the excess
the first line of defense and the preferred method      pressure is not used, the system is described as      anesthetic gases can be deposited into the exhaust
of control to protect employees from exposure           a passive system. With an active system, there        stream either at the exhaust grille or further
to anesthetic gases. An effective anesthetic gas        will be a negative pressure in the gas disposal       downstream in the exhaust duct.
scavenging system traps waste gases at the              tubing. With a passive system, this pressure
                                                                                                              Concern for fuel economy has increased the use
site of overflow from the breathing circuit and         will be increased above atmospheric (positive)
                                                                                                              of systems that recirculate air. Recirculating
disposes of these gases to the outside atmosphere.      by the patient exhaling passively, or manual
                                                                                                              HVAC/ventilation systems return part of the
The heating, ventilating and air conditioning           compression of the breathing system reservoir
                                                                                                              exhaust air back into the air intake and recirculate
(HVAC) system also contributes to the dilution          bag.
                                                                                                              the mixture through the room. Thus, only a
and removal of waste gases not collected by the         Use of a central vacuum system is an example of       fraction of the exhaust air is disposed of to the
scavenging system or from other sources such            an active system: The waste anesthetic gases are      outside. To maintain minimal levels of anesthetic
as leaks in the anesthetic apparatus or improper        moved along by negative pressure. Venting waste       exposure, air that is to be recirculated must
work practices.                                         anesthetic gas via the exhaust grille or exhaust      not contain anesthetic gases. Consequently,
The exhalation of residual gases by patients in the     duct of a nonrecirculating ventilation system is an   recirculating systems employed as a disposal
PACU may result in significant levels of waste          example of a passive system: The anesthetic gas       pathway for waste anesthetic gases must not be
anesthetic gases when appropriate work practices        is initially moved along by the positive pressure     used for gas waste disposal. The exception is an
are not used at the conclusion of the anesthetic        from the breathing circuit until it reaches the gas   arrangement that transfers waste gases into the
or inadequate ventilation exists in the PACU. A         disposal assembly.                                    ventilation system at a safe distance downstream
nonrecirculating ventilation system can reduce                                                                from the point of recirculation to ensure that the
                                                        Active systems
waste gas levels in this area. Waste gas emissions                                                            anesthetic gases will not be circulated elsewhere
                                                        Excess anesthetic gases may be removed by
to the outside atmosphere must meet local, state,                                                             within the building.
                                                        a central vacuum system (servicing the ORs
and Environmental Protection Agency (EPA)
                                                        in general) or an exhaust system dedicated to         Under certain circumstances, a separate duct
regulatory requirements.
                                                        the disposal of excess gases. When the waste          for venting anesthetic gases directly outside
A scavenging system consists of five basic              anesthetic gas scavenging system is connected         the building without the use of a fan may be an
components (ASTM, F 1343 - 91):                         to the central vacuum system (which is shared         acceptable alternative. By this technique, excess
 A gas collection assembly, such as a                  by other users, e.g., surgical suction), exposure     anesthetic gases may be vented through the
    collection manifold or a distensible bag            levels may be effectively controlled. The central     wall, window, ceiling or floor, relying only on
    (i.e., Jackson-Rees pediatric circuit), which       vacuum system must be specifically designed           the slight positive pressure of the gases leaving
    captures excess anesthetic gases at the site        to handle the large volumes of continuous             the gas collection assembly to provide the flow.
    of emission, and delivers it to the transfer        suction from OR scavenging units. If a central        However, several limitations are apparent. A
    tubing.                                             vacuum system is used, a separate, dedicated gas      separate line would be required for each OR to
 Transfer tubing, which conveys the excess             disposal assembly tubing should be used for the       prevent the cross-contamination with anesthetic
    anesthetic gases to the interface.                  scavenging system, distinct from the tubing used      gases among the ORs. A safe disposal site would
 The interface, which provides positive (and           for patient suctioning (used for oral and nasal       be necessary. The possible effects of variations
    sometimes negative) pressure relief and may         gastric sources as well as surgical suctioning).      in wind velocity and direction would require
    provide reservoir capacity. It is designed to                                                             a means for preventing a reverse flow in the
                                                        Similarly, when a dedicated exhaust system
    protect the patient’s lungs from excessive                                                                disposal system. Occlusion of the outer portion of
                                                        (low velocity) is used, excess gases can also be
    positive or negative scavenging system                                                                    such a passive system by ice or by insect or bird
                                                        collected from one or more ORs and discharged
    pressure.                                                                                                 nests is also possible. The outside opening of a
                                                        to the outdoors. The exhaust fan must provide
 Gas disposal assembly tubing, which                                                                         through-wall, window, ceiling or floor disposal
                                                        sufficient negative pressure and air flow so that
    conducts the excess anesthetic gases from the                                                             assembly should be directed downward, shielded
                                                        cross-contamination does not occur in the other
    interface to the gas disposal assembly.                                                                   and screened to prevent the entrance of foreign
                                                        ORs connected to this system. Active systems
Page 36                                                                                                                                                 Elite CME
matter or ice buildup. Despite these limitations,        considered in developing inspection and            Administrative controls
the separate duct without the use of a fan may be        testing procedures for equipment checkout          Administrative controls represent another
ideal in older facilities constructed with windows       prior to administering an anesthetic.              approach for reducing worker exposure to waste
that cannot be opened and in the absence of             If a face mask is to be used for administration    gases other than through the use of engineering
nonrecirculating air conditioning.                       of inhaled anesthetics, it should be available     controls, work practices, or personal protective
                                                         in a variety of sizes to fit each patient          equipment. Administrative controls may be
Absorbers can also trap most excess anesthetic
                                                         properly. The mask should be pliable and           thought of as any administrative decision that
gases. Canisters of varying shapes and capacities
                                                         provide as effective a seal as possible against    results in decreased anesthetic-gas exposure. For
filled with activated charcoal have been used as
                                                         leakage into the surrounding air.                  workers potentially exposed to waste anesthetic
waste gas disposal assemblies by directing the
                                                        Tracheal tubes, laryngeal masks, and other         gases, the program administrator should establish
gases from the gas disposal tubing through them.
                                                         airway devices should be positioned precisely      and implement policies and procedures to:
Activated charcoal canisters will effectively
                                                         and the cuffs inflated adequately.                  Institute a program of routine inspection
adsorb the vapors of halogenated anesthetics, but
                                                        Vaporizers should be filled in a well-                 and regular maintenance of equipment in
not N2O. The effectiveness of individual canisters
                                                         ventilated area and in a manner to minimize            order to reduce anesthetic gas leaks and to
and various brands of charcoal vary widely.
                                                         spillage of the liquid agent. This can be              have the best performance of scavenging
Different potent inhaled volatile agents are
                                                         accomplished by using a specialized “key-              equipment and room ventilation. Preventive
adsorbed with varying efficiencies. The efficiency
                                                         fill” spout to pour the anesthetic into the            maintenance should be performed by trained
of adsorption also depends on the rate of gas flow
                                                         vaporizer instead of pouring from a bottle             individuals according to the manufacturer’s
through the canister. The canister is used where
                                                         into a funnel-fill vaporizer. When feasible,           recommendations and at intervals determined
portability is necessary. The disadvantages are
                                                         vaporizers should be filled at the location            by equipment history and frequency of use.
that they are expensive and must be changed
                                                         where the anesthetic will be administered              Preventive maintenance includes inspection,
frequently. Canisters must be used and discarded
                                                         and, when filled electively, with the fewest           testing, cleaning, lubrication and adjustment
in the appropriate manner, as recommended by
                                                         possible personnel present in the room.                of various components. Worn or damaged
the manufacturer.
                                                         Vaporizers should be turned off when not in            parts should be repaired or replaced. Such
general or dilution ventilation                          use.                                                   maintenance can result in detection of
An effective room HVAC system when used in              Spills of liquid anesthetic agents should be           deterioration before an overt malfunction
combination with an anesthetic gas scavenging            cleaned up promptly.                                   occurs. Documentation of the maintenance
system should reduce, although not entirely             Before extubating the patient’s trachea                program should be kept indicating the nature
eliminate, the contaminating anesthetic gases.           or removing the mask or other airway                   and date of the work performed, as well as
If excessive concentrations of anesthetic gases          management device, one should administer               the name of the trained individual servicing
are present, then airflow should be increased            non-anesthetic gases/agents so that the                the equipment.
in the room to allow for more air mixing and             washed-out anesthetic gases can be removed          Implement a monitoring program to measure
further dilution of the anesthetic gases. Supply         by the scavenging system. The amount of                airborne levels of waste gases in the breathing
register louvers located in the ceiling should be        time allowed for this should be based on               zone or immediate work area of those most
designed to direct the fresh air toward the floor        clinical assessment and may vary from                  heavily exposed (e.g., anesthesiologist,
and toward the health care workers to provide            patient to patient. When possible, flushing of         nurse anesthetist, oral surgeon) in each
dilution and removal of the contaminated air             the breathing system should be achieved by             anesthetizing location and PACU. Periodic
from the operatory or PACU. Exhaust register             exhausting into the scavenging system rather           monitoring (preferably at least semiannually)
louvers should be properly located (usually low          than into the room air.                                of waste gas concentrations is needed to
on the wall near the floor level) in the room to        Work practices performed by biomedical                 ensure that the anesthesia delivery equipment
provide adequate air distribution. They should not       engineers and technicians also contribute              and engineering/environmental controls work
be located near the supply air vents because this        significantly to the efficacy of managing              properly and that the maintenance program
will short-circuit the airflow and prevent proper        waste gas exposure. It is, therefore, important        is effective. Monitoring may be performed
air mixing and flushing of the contaminants from         for this group of workers to do the following:         effectively using conventional time-weighted
the room.                                                Š Monitor airborne concentrations of                   average air sampling or real-time air
                                                              waste gases by sampling, measuring,               sampling techniques.
Work practices                                                and reporting data to the institution’s        Encourage or promote the use of scavenging
Work practices, as distinct from engineering                  administration. Air monitoring for waste          systems in all anesthetizing locations
controls, involve the way in which a task is                  anesthetic gases should include both              where inhaled agents are used, recognizing
performed. OSHA has found that appropriate                    personal sampling (i.e., in a health-             that a waste gas scavenging system is the
work practices can be a vital aid in reducing the             care worker’s breathing zone) and area            most effective means of controlling waste
exposures of OR personnel to waste anesthetic                 sampling.                                         anesthetic gases.
agents. In contrast, improper anesthetizing              Š Assist in identifying sources of waste/           Implement an information and training
techniques can contribute to increased waste                  leaking gases and implementing                    program for employees exposed to
gas levels. These techniques can include an                   corrective action.                                anesthetic agents that complies with OSHA’s
improperly selected and fitted face mask, an             Š Determine whether the scavenging                     Hazard Communication Standard (29
insufficiently inflated tracheal tube cuff, an                system is designed and functioning                CFR 1910.1200) so that employees can
improperly positioned laryngeal mask, or other                properly to remove the waste anesthetic           meaningfully participate in, and support,
airway, and careless filling of vaporizers and                gases from the breathing circuit, and             the protective measures instituted in their
spillage of liquid anesthetic agents.                         ensure that the gases are vented from             workplace.
General work practices recommended for                        the workplace in such a manner that            Define and implement appropriate work
anesthetizing locations include the following:                occupational re-exposure does not occur           practices to help reduce employee exposure.
 A complete anesthesia apparatus checkout                    (e.g., smoke trail tests of exhaust grilles       Training and educational programs covering
    procedure should be performed each day                    used with passive scavenging systems).            appropriate work practices to minimize
    before the first case. An abbreviated version        Š Ensure that operatory and PACU                       levels of anesthetic gases in the operating
    should be performed before each subsequent                ventilation systems provide sufficient            room should be conducted at least annually.
    case. The FDA Anesthesia Apparatus                        room air exchange to reduce ambient               Employers should emphasize the importance
    Checkout Recommendations should be                        waste gas levels.                                 of implementing these practices and should
Elite CME                                                                                                                                              Page 37
    ensure that employees are properly using the      rebreathing. The Mapleson D system and the             Engineering controls
    appropriate techniques on a regular basis.        Jackson-Rees modification of the Ayre’s T-piece        As a result of using appropriate anesthetic gas
   Implement a medical surveillance program          are examples of limited rebreathing systems that       scavenging in ORs, the levels of contamination
    for all workers exposed to waste gases.           require appropriate scavenging equipment.              have been decreased. In the PACU, however,
   Ensure the proper use of personal protective                                                             the principle of scavenging as practiced in
                                                      The following work practices may be employed
    equipment during cleanup and containment of                                                              the OR is not widely accepted due to medical
                                                      with any of the above breathing circuits:
    major spills of liquid anesthetic agents.                                                                considerations and consequently is infrequently
                                                       Empty the contents of the reservoir bag
   Manage disposal of liquid agents, spill                                                                  employed as a source-control method for
                                                          directly into the anesthetic gas scavenging
    containment, and air monitoring for waste                                                                preventing the release of waste anesthetic gases
                                                          system and turn off the flow of N2O and
    gases following a spill.                                                                                 into the PACU environment. Most PACUs
                                                          any halogenated anesthetic agent prior to
   Comply with existing federal, state, and                                                                 provide care to multiple patients in beds without
                                                          disconnecting the patient circuit.
    local regulations and guidelines developed                                                               walls between them, and convective currents
                                                       Turn off the flow of N2O and the vaporizer,
    to minimize personnel exposure to waste                                                                  move the gases from their source to other areas.
                                                          if appropriate, when the patient circuit is
    anesthetic gases, including the proper                                                                   Therefore, in the PACU, a properly designed
                                                          disconnected from the patient, for example,
    disposal of hazardous chemicals.                                                                         and operating dilution ventilation system should
                                                          for oral or tracheal suctioning.
                                                                                                             be relied upon to minimize waste anesthetic gas
Location-specific workplace controls                   Test daily for low-pressure leaks throughout
                                                          the entire anesthesia system. All leaks            concentrations. This system should provide a
This section describes engineering and work
                                                          should be minimized before the system is           recommended minimum total of 6 air changes per
practice controls specific to hospital ORs,
                                                          used. Starting anesthetic gas flow before the      hour with a minimum of 2 air changes of outdoor
PACUs, dental operatories and veterinary clinics
                                                          actual induction of anesthesia begins is not       air per hour to adequately dilute waste anesthetic
and hospitals. Operational procedures relating
                                                          acceptable. For techniques to rapidly induce       gases. Room exhaust containing waste anesthetic
to engineering controls are also discussed where
                                                          anesthesia using inhaled agents (single-breath     gases should not be recirculated to other areas of
                                                          mask induction), the patient connector should      the hospital.
Hospital operating rooms
                                                          be occluded when filling the breathing circuit     Work practices
For years, anesthesia providers tolerated exposure
                                                          with nitrous oxide or halogenated agent prior      PACU managers should consider:
to waste anesthetic gases and regarded it as an
                                                          to applying the mask to the patient’s face.         Periodic exposure monitoring with particular
inevitable consequence of their work. Since the
                                                      If the circle absorber system (Figure 6 - located         emphasis on peak gas levels in the breathing
1970s, anesthesiologists have steadily worked
                                                      at end of this chapter) is used, the following            zone of nursing personnel working in the
to improve equipment and technique to reduce
                                                      additional work practices can be employed:                immediate vicinity of the patient’s head.
workplace exposures to waste anesthetic gases,
                                                       Adjust the vacuum needle valve as needed                Methods using random room sampling to
and significant progress has been made. In early
                                                           to regulate the flow of waste anesthetic             assess ambient concentrations of waste
delivery equipment, waste gases were exhausted
                                                           gases into the vacuum source in an active            anesthetic gases in the PACU are not an
through the APL or “pop-off” valve into the face
                                                           scavenging system. Adjustments prevent the           accurate indicator of the level of exposure
of the anesthesia provider and were distributed
                                                           bag from overdistending by maintaining the           experienced by nurses providing bedside
into the room air. Present practice, which utilizes
                                                           volume in the scavenging system reservoir            care. Because of the closeness of the PACU
an efficient scavenging system, avoids this type
                                                           bag between empty and half-full. In machines         nurse to the patient, such methods would
of contamination by collecting the excess gases
                                                           that use an open reservoir to receive waste          consistently underestimate the level of waste
immediately at the APL valve.
                                                           gas, a flow meter is used to adjust the rate of      anesthetic gases in the breathing zone of the
Engineering controls                                                                                            bedside nurse.
                                                           gas flow to the vacuum system.
Waste gas evacuation is required for every                                                                    Application of a routine ventilation system
                                                       Cap any unused port in a passive waste gas
type of breathing circuit configuration with the                                                                maintenance program to keep waste gas
                                                           scavenging configuration.
possible exception of a closed circuit, because                                                                 exposure levels to a minimum.
most anesthesia techniques typically use more         Postanesthesia care in hospitals and
fresh gas flow than is required. Appropriate waste
                                                                                                             Dental operatory
                                                      stand-alone facilities                                 Mixtures of N2O and oxygen have been used in
gas evacuation involves collection and removal        Because the patient is the main source of waste        dentistry as general anesthetic agents, analgesics
of waste gases, detection and correction of leaks,    anesthetic gases in the PACU, it becomes               and sedatives for more than 100 years. The usual
consideration of work practices, and effective        more difficult to control health-care workers’         analgesia equipment used by dentists includes a
room ventilation. To minimize waste anesthetic        exposures to waste anesthetic gases. The unique        N2O and O2 delivery system, a gas mixing bag
gas concentrations in the operating room, the         PACU environment coupled with the patient’s            and a nasal mask with a positive pressure relief
recommended air exchange rate (room dilution          immediate condition upon arrival from surgery          valve. The analgesia machine is usually adjusted
ventilation) is a minimum total of 15 air changes     require different work practices than those            to deliver more of the analgesic gas mixture than
per hour with a minimum of 3 air changes of           routinely used in ORs. Patients undergoing             the patient can use.
outdoor air (fresh air) per hour. Operating room      general anesthesia usually have their airways
air containing waste anesthetic gases should not      secured using a tracheal tube with an inflatable       Analgesia machines for dentistry are designed
be recirculated to the operating room or other        cuff that seals the tube within the trachea. The       to deliver up to 70 percent (700,000 ppm) N2O
hospital locations.                                   seal between the tracheal tube cuff and the            to a patient during dental surgery. The machine
                                                      trachea (or between the face mask and the face)        restricts higher concentrations of N2O from being
Work practices
                                                      is essential for maintaining a gas-tight system        administered to protect the patient from hypoxia.
In most patients, a circle absorption system is
                                                      that permits effective scavenging in the OR.           In most cases, patients receive between 30 and
used and can be easily connected to a waste
                                                      The tracheal tube connects the patient with            50 percent N2O during surgery. The amount of
gas scavenging system. In pediatric anesthesia,
                                                      the breathing circuit that is connected to the         time N2O is administered to a patient depends on
systems other than those with a circle absorber
                                                      scavenging system in the OR. Once the patient          the dentist’s judgment of patient needs and the
may be used. Choice of the breathing circuit that
                                                      reaches the PACU, scavenging systems such as           complexity of the surgery. The most common
best meets the needs of pediatric patients may
                                                      those used in the OR are no longer effective,          route of N2O delivery and exhaust is through a
alter a clinician’s ability to scavenge waste gas
                                                      since the patient is no longer connected to the        nasal scavenging mask applied to the patient.
effectively. Breathing circuits frequently chosen
for neonates, infants and small children are          breathing circuit. Other less-effective methods of     Some dentists administer N2O at higher
usually valveless, have low resistance and limit      waste gas removal are thus relied upon.                concentrations at the beginning of the operation,
Page 38                                                                                                                                               Elite CME
then decrease the amount as the operation              over the patient’s nose as snugly as possible            Encourage the patient to minimize talking,
progresses. Others administer the same amount          without impairing the vision or dexterity of the          mouth breathing and facial movement while
of N2O throughout the operation. When the              dentist. Gases exhaled orally are not captured by         the mask is in place.
operation is completed, the N2O is turned              the nasal mask. A flow rate of approximately 45          During N2O administration, the reservoir bag
off. Some dentists turn the N2O on only at             L/min has been recommended as the optimum                 should be periodically inspected for changes
the beginning of the operation, using N2O as           rate to prevent significant N2O leakage into the          in tidal volume, and the vacuum flow rate
a sedative during the administration of local          room air.                                                 should be verified.
anesthesia, and turn it off before operating           A newer type of mask is a frequent choice in             On completing anesthetic administration and
procedures. Based on variations in dental              dental practice, a single-patient-use nasal hood.         before removing the mask, non-anesthetic
practices and other factors in room air, N2O           This mask does not require sterilization after            gases/agents should be delivered to the
concentrations can vary considerably for each          surgery because it is used by only one patient and        patient for a sufficient time based on clinical
operation and also vary over the course of the         is disposable.                                            assessment that may vary from patient to
operation.                                                                                                       patient. In this way, both the patient and the
                                                       In a dental operatory, a scavenging system is part        system will be purged of residual N2O. Do
Unless the procedure is performed under general        of a high-volume evacuation system used with a
anesthesia in an OR, halogenated anesthetics are                                                                 not use an oxygen flush.
                                                       dental unit. The vacuum system may dispose of a
not administered, nor does the patient undergo         combination of waste gases, oral fluid and debris,    Cleanup and disposal of liquid anesthetic
laryngoscopy and tracheal intubation. In the           and is not limited to waste gas removal. The          agent spills
typical dental office procedure, the nasal mask is     exhaust air of the evacuation system should be        Small volumes of liquid anesthetic agents such
placed on the patient, fitted and adjusted prior to    vented outside the building and away from fresh-      as halothane, enflurane, isoflurane, desflurane,
administration of the anesthetic agent. The mask       air inlets and open windows to prevent re-entry of    and sevoflurane evaporate readily at normal
is designed for the nose of the patient because        gas into the operatory.                               room temperatures, and may dissipate before
access to the patient’s mouth is essential for                                                               any attempts to clean up or collect the liquid
dental procedures.                                     The general ventilation should provide good
                                                                                                             are initiated. However, when large spills occur,
                                                       room air mixing. In addition, auxiliary (local)
A local anesthetic, if needed, is typically                                                                  such as when one or more bottles of a liquid
                                                       exhaust ventilation used in conjunction with
administered after the N2O takes effect. The                                                                 agent break, specific cleaning and containment
                                                       a scavenging system has been shown to be
patient’s mouth is opened and the local anesthetic                                                           procedures are necessary and appropriate
                                                       effective in reducing excess N2O in the breathing
is injected. The dental procedure begins after                                                               disposal is required. The recommendations of
                                                       zone of the dentist and dental assistant, from
the local anesthetic takes effect. The patient                                                               the chemical manufacturer’s material safety data
                                                       nasal mask leakage and patient mouth breathing.
opens his/her mouth but is instructed to breathe                                                             sheet (MSDS) that identify exposure reduction
                                                       This type of ventilation captures the waste
through the nose. Nonetheless, a certain amount                                                              techniques for spills and emergencies should be
                                                       anesthetic gases at their source. However, there
of mouth breathing frequently occurs. The dentist                                                            followed.
                                                       are practical limitations in using it in the dental
may periodically stop the dental procedure for a                                                             In addition, OSHA Standard for Hazardous
                                                       operatory. These include proximity to the patient,
moment to allow the patient to close the mouth                                                               Waste Operations and Emergency Response
                                                       interference with dental practices, noise, and
and breathe deeply to re-establish an appropriate                                                            would apply if emergency response efforts are
                                                       installation and maintenance costs. It is most
concentration of N2O in the patient’s body before                                                            performed by employees. The employer must
                                                       important that the dentist not work between the
resuming the procedure. Depending on the                                                                     determine the potential for an emergency in a
                                                       patient and a free-standing local exhaust hood.
nature of the procedure, high velocity suction                                                               reasonably predictable worst-case scenario, and
                                                       Doing so will cause the contaminated air to
is regularly used to remove intraoral debris                                                                 plan response procedures accordingly. Only
                                                       be drawn through the dentist’s breathing zone.
and, when used, creates a negative air flow and                                                              adequately trained and equipped workers may
                                                       These auxiliary ventilation systems are not now
captures some of the gas exhaled by the patient.                                                             respond to spills. When the situation is unclear
                                                       commercially available. The Academy of General
At the end of the procedure, the nosepiece is left     Dentistry also emphasizes properly installed and      or data are lacking on the exposure level, the
on the patient while the N2O is turned off and the     maintained analgesia delivery systems.                response needs to be the same as for high levels
oxygen flow is increased. The anesthetic mixture                                                             of exposure. Responses to incidental releases
diffuses from the circulating blood into the lungs     Work practices                                        of liquid anesthetic agents where the substance
and is exhaled. Scavenging is continued while the       Prior to first use each day of the N2O machine      can be absorbed, neutralized or otherwise
patient is eliminating the N2O.                          and every time a gas cylinder is changed, the       controlled at the time of release by employees in
                                                         low-pressure connections should be tested           the immediate release area, or by maintenance
The dental office or operatory should have a             for leaks. High-pressure line connections
properly installed N2O delivery system. This                                                                 personnel do not fall within the scope of this
                                                         should be tested for leaks quarterly. A soap        standard.
includes appropriate scavenging equipment with           solution may be used to test for leaks at
a readily visible and accurate flow meter (or            connections. Alternatively, a portable infrared     Because of the volatility of liquid anesthetics,
equivalent measuring device), a vacuum pump              spectrophotometer can be used to detect an          rapid removal by suctioning in the OR is the
with the capacity for up to 45 L/min of air per          insidious leak.                                     preferred method for cleaning up spills. Spills
workstation, and a variety of sizes of masks to        	 Prior to first use each day, inspect all N2O       of large volumes in poorly ventilated areas or
ensure proper fit for individual patients.                equipment (e.g., reservoir bag, tubing, mask,      in storage areas should be absorbed using an
A common nasal mask, shown in Figure 7                    connectors) for worn parts, cracks, holes, or      absorbent material, sometimes called a sorbent,
(located at the end of this chapter), consists of an      tears. Replace as necessary.                       that is designed for cleanup of organic chemicals.
inner and a slightly larger outer mask component.       Connect mask to the tubing and turn on              “Spill pillows” commonly used in hospital
The inner mask has two hoses connected that              vacuum pump. Verify appropriate flow                laboratories, vermiculite, and carbon-based
supply anesthetic gas to the patient. A relief           rate (i.e., up to 45 L/min or manufacturer’s        sorbents are some of the materials commercially
valve is attached to the inner mask to release           recommendations).                                   available and regularly used for this purpose.
excess N2O into the outer mask. The outer mask          A properly sized mask should be selected and        Caution should be exercised if broken glass
has two smaller hoses connected to a vacuum              placed on the patient. A good, comfortable fit      bottles pose a hazard.
system to capture waste gases from the patient           should be ensured. The reservoir (breathing)        Both enflurane and desflurane are considered
and excess gas supplied to the patient by the            bag should not be over- or underinflated            hazardous wastes under the EPA regulations
analgesia machine. The nasal mask should fit             while the patient is breathing oxygen (before       because these chemicals contain trace amounts of
                                                         administering N2O).

Elite CME                                                                                                                                                Page 39
chloroform (a hazardous substance), a byproduct       are necessary to establish proper engineering,            Information Manual under IMIS:1953.
of the manufacturing process. Consequently,           work practice, and administrative controls to             The minimum sampling duration for the
sorbents that have been saturated with enflurane      ensure the lowest reasonably achievable gas               dosimeter is 15 minutes; however, it can be
or desflurane should be managed as an EPA             levels in the operatory and PACU room air.                used for up to 16 hours of passive sampling.
hazardous waste material due to the trace             OSHA recommends that air sampling for                     This sampler has not been validated by
concentrations of chloroform present. Isoflurane      anesthetic gases be conducted every six months            OSHA. Other dosimeters are commercially
and halothane do not contain trace amounts of         to measure worker exposures and to check the              available and can be used. Although not
chloroform or any other regulated substance and       effectiveness of control measures. Furthermore,           validated by OSHA at this time, they may
are therefore not considered hazardous wastes by      OSHA recommends that only the agents most                 be validated in the future. Five liter, 5-layer
EPA.                                                  frequently used need to be monitored, since               aluminized gas sampling bags can also be
                                                      proper engineering controls, work practices               used to collect a sample.
To minimize exposure to all liquid anesthetic
                                                      and control procedures should reduce all agents          Halogenated agents
agents during cleanup and to limit exposure
                                                      proportionately. However, the decision to monitor         Three chlorofluorocarbon-based anesthetic
during disposal procedures, the following general
                                                      only selected agents could depend not only on             agents (halothane, enflurane, and isoflurane)
guidelines are recommended. The waste material
                                                      the frequency of their use, but on the availability       and one fluorocarbon-based agent
should be placed in a container, tightly sealed,
                                                      of an appropriate analytical method and the cost          (desflurane) are listed in the Chemical
properly labeled, and disposed of with other
                                                      of instrumentation. ASA emphasizes regular                Information Manual. The OSHA sampling
chemical wastes sent to a facility’s incinerator or
                                                      maintenance of equipment and scavenging                   procedure for halothane is listed under
removed by a chemical waste contractor. After
                                                      systems, daily check-out procedures for                   IMIS:0395; for enflurane, under IMIS:1038;
a large spill has occurred and the appropriate
                                                      anesthesia equipment, and education to ensure             for isoflurane, under IMIS:F118; and for
response action taken, airborne monitoring
                                                      use of appropriate work practices. It does not            desflurane, under IMIS:R218.
should be conducted to determine whether the
spill was effectively contained and cleaned up.       believe that a routine monitoring program is              The current recommended media sampling
                                                      necessary when these actions are being carried            for halothane, enflurane and isoflurane
Determination of appropriate disposal procedures
                                                      out. ASA prefers to use monitoring when                   requires an Anasorb 747 tube (140/70 mg
for each facility is the sole responsibility of
                                                      indicated, such as in the event of known or               sections) or an Anasorb CMS tube (150/75
that facility. Empty anesthetic bottles are not
                                                      suspected equipment malfunction.                          mg. sections). The sample can be taken at a
considered regulated waste and may be discarded
                                                      Three fundamental types of air samples can                flow rate of 0.5 L/min. Total sample volumes
with ordinary trash or recycled. Furthermore, the
                                                      be taken in order to evaluate the workplace:              not exceeding 12 liters are recommended.
facility as well as the waste handling contractor
                                                      personal, area and source samples. Personal               The current recommended sampling media
must comply with all applicable federal, state,
                                                      samples give the best estimate of a worker’s              for desflurane requires an Anasorb 747
and local regulations.
                                                      exposure level because they represent the                 tube (140/70 mg sections). The sample
To minimize exposure to waste liquid anesthetic       actual airborne contaminant concentration                 can be taken at a flow rate of 0.05 L/min.
agents during cleanup and disposal, the following     in the worker’s breathing zone during the                 Total sample volumes not exceeding 3
general guidelines are recommended by the             sampling period. This is the preferred method             liters are recommended. All four sampling
manufacturers of liquid anesthetic agents:            for determining a worker’s time-weighted                  methodologies are fully validated analytical
 Wear appropriate personal protective                average (TWA) exposure and should be used                 procedures.
   equipment. Where possible, ventilate area of       to assess personal exposures during anesthetic
   spill or leak. Appropriate respirators should
                                                                                                            Real-time sampling
                                                      administration and in the PACU. Where several         Sampling that provides direct, immediate, and
   be worn.                                           health care workers perform the same job, on          continuous (real-time) readout of anesthetic gas
 Restrict persons not wearing protective             the same shift, and in the same work area, and        concentrations in ambient air utilizes a portable
   equipment from areas of spills or leaks until      the length, duration, and level of waste gas          infrared spectrophotometer. Since this method
   cleanup is complete.                               exposures are similar, an employer may sample a       provides continuous sampling and instantaneous
 Collect the liquid spilled and the absorbent        representative fraction of the employees instead      feedback, sources of anesthetic gas leakage
   materials used to contain a spill in a glass       of all employees.                                     and effectiveness of control measures can be
   or plastic container. Tightly cap and seal
                                                      Area sampling is useful for evaluating overall        immediately determined.
   the container and remove it from the
   anesthetizing location. Label the container        air contaminant levels in a work area and for         Additional sampling guidelines
   clearly to indicate its contents.                  investigating cross-contamination with other          If it should ever be necessary to enter an
 Transfer the sealed containers to the waste         areas in the health care facility. Source sampling    operating room to conduct air sampling, the
   disposal company that handles and hauls            can be used to detect leaks in the anesthesia         following guidelines provide the information
   waste materials.                                   delivery and scavenging systems as well as            needed. Individuals performing air sampling
 Health-care facilities that own or operate          ineffective capture by the scavenging system.         should be familiar with and follow all OR
   medical waste incinerators may dispose of          Thus, how samples are taken is a critical point in    procedures for access into and out of the surgical
   waste anesthetics by using an appropriate          any safety program.                                   suite with particular attention to sterile and
   incineration method after verifying that           The OSHA Chemical Information Manual                  nonsterile areas. The patient is the center of
   individual incineration operating permits          contains current sampling technology for several      the sterile field, which includes the areas of the
   allow burning of anesthetic agents at each         of the anesthetic gases that may be present in        patient, operating table, and furniture covered
   site.                                              anesthetizing locations and PACUs. Some of            with sterile drapes and the personnel wearing
                                                      the sampling methods available are summarized         sterile attire. Sampling in the breathing zone of
Air monitoring                                        below.                                                surgeons and other nursing or technical personnel
Air monitoring is one of the fundamental
                                                                                                            who work in the sterile field must conform to the
tools used to evaluate workplace exposures.           Time-integrated sampling
                                                                                                            principles of sterile field access. Strict adherence
Accordingly, this section presents some of the           Nitrous oxide
                                                                                                            to sound principles of sterile technique and
appropriate methods that can be used to detect            Personal N2O exposures can be determined
                                                                                                            recommended practices is mandatory for the
and measure the concentration of anesthetic               by using the VAPOR-TRAK nitrous oxide
                                                                                                            safety of the patient.
gases that may be present in the health care              passive monitor (sometimes called a
environment. The data provided by monitoring              “passive dosimeter” or “diffusive sampler”)       Generally speaking, each hospital has its own
                                                          as referenced in the 2000 OSHA Chemical           guidelines for proper OR attire and other safety
Page 40                                                                                                                                               Elite CME
procedures. These rules should be strictly             Each MSDS must be in English, although                      gases and other hazardous chemicals in the
followed by anyone entering the OR. There are          the employer may maintain copies in other                   work area (such as monitoring conducted by
standard uniform guidelines that apply to all          languages as well, and must include information             the employer, continuous monitoring devices,
hospitals. Only clean and/or freshly laundered         regarding the specific chemical identity of the             and the appearance or odor of chemicals
OR attire is worn in the OR. Proper attire consists    anesthetic gases or hazardous chemical and                  when released).
of body covers such as a two-piece pantsuit            its common names. In addition, information
                                                                                                             Personnel training records are not required to
(scrub suit), head cover (cap or hood), mask,          must be provided on the physical and chemical
                                                                                                             be maintained, but such records would assist
and shoe covers. A sterile gown is worn over the       characteristics of the hazardous chemical, known
                                                                                                             employers in monitoring their programs to ensure
scrub suit to permit the wearer to come within         acute and chronic health effects and related health
                                                                                                             that all employees are appropriately trained.
the sterile field. Other attire such as gloves and     information, primary route(s) of entry, exposure
                                                                                                             Employers can provide employees information
eyewear may be required. Some hospitals, but           limits, precautionary measures, emergency and
                                                                                                             and training through whatever means are found
not all, may allow persons coming into the OR          first-aid procedures, and the identification of the
                                                                                                             appropriate and protective. Although there
to wear a clean gown (in addition to the cap,          organization responsible for preparing the sheet.
                                                                                                             would always have to be some training on-site
the mask, and the shoe covers) over their street       As a source of detailed information on hazards,
                                                                                                             (such as informing employees of the location
clothes if they are not going to remain in the OR      copies of the MSDS for each hazardous chemical
                                                                                                             and availability of the written program and
for longer than 10-15 minutes.                         must be readily accessible during each work shift
                                                                                                             MSDSs), employee training may be satisfied in
                                                       to employees when they are in their work area(s).
In regard to decontaminating outside equipment,                                                              part by general training about the requirements
each hospital has its own policy. However, the         Employers must prepare a list of all hazardous        of the hazard communication standard and about
common practice is to “wipe off” all surfaces          chemicals in the workplace, and the list should       chemical hazards on the job which is provided
with a chemical disinfectant. Most hospitals use       be checked to verify that MSDSs have been             by, for example, professional associations,
Wescodyne or other phenolic solutions. Good            received for each chemical. If there are hazardous    colleges, universities, and training centers.
physical cleaning before disinfection helps            chemicals used for which no MSDS has been             In addition, previous training, education and
reduce the number of microorganisms present            received, the employer must contact the supplier,     experience of a worker may relieve the employer
and enhances biocidal action.                          manufacturer or importer to obtain the missing        of some of the burdens of informing and training
                                                       MSDS.                                                 that worker. The employer, however, maintains
Any person not familiar with the OR is usually
                                                                                                             the responsibility to ensure that employees are
instructed by a scrub nurse on all the safety          Health care employers must establish a training
                                                                                                             adequately trained and are equipped with the
procedures pertaining to the hospital. The scrub       and information program for all personnel who
                                                                                                             knowledge and information to do their jobs
nurse will also provide instructions on hand           are involved in the handling of, or who have
scrubbing and other procedures that may be             potential exposure to, anesthetic gases and other
necessary. Persons entering the OR must follow         hazardous chemicals to apprise them of the                 Step-by-step approach for controlling N2O
these guidelines and instructions.                     hazards associated with these chemicals in the
                                                       workplace. Training relative to anesthetic gases       Step           Procedure              Control
In addition, it should be recognized that the
                                                       should place an emphasis on reproductive risks.        1         Visually inspect        Replace
patient’s welfare, safety, and rights of privacy are
                                                       Training and information must take place at the                  all N2O equipment       defective
                                                       time of initial assignment and whenever a new                    (reservoir bag,         equipment and/
Hazard communication                                   hazard is introduced into the work area. At a                    hoses, mask,            or parts.
In accordance with the Hazard Communication            minimum, employees must be informed of the                       connectors) for worn
Standard (29 CFR 1910,1200), employers in              following:                                                       parts, cracks, holes,
health care facilities must develop, implement          The Hazard Communication Standard (29                          or tears.
and maintain at the workplace a written,                   CFR 1910.1200) and its requirements.               2         Turn on the N2O         Determine leak
comprehensive hazard communication program              Any operations and equipment in the work                       tank and check          source and fix.
that includes provisions for container labeling,           area where anesthetic agents and hazardous                   all high- to low-       If tank valve
collection and availability of material safety data        chemicals are present.                                       pressure connections    leaks, replace
sheets (MSDSs), and an employee training and            Location and availability of the written                       for leaks. Use          tank; if O-rings,
information program. The standard also requires            hazard communication program including the                   a non-oil-based         gaskets, valves,
a list of hazardous chemicals in the workplace             required lists of hazardous chemicals and the                soap solution to        hoses, or
as part of the written hazard communication                required MSDS forms.                                         check for bubbles       fittings, replace.
program.                                               The employee training program must consist of                    at high pressure        Contact the
                                                       the following elements:                                          connectors, or use a    manufacturer
Any chemicals subject to the labeling
                                                        How the hazard communication program is                        portable infrared gas   for parts
requirements of the FDA are exempt from
                                                           implemented in the workplace, how to read                    analyzer.               replacement.
the labeling requirements under the Hazard
                                                           and interpret information on the MSDS and                                            For threaded
Communication Standard. This includes such
                                                           label of each hazardous chemical, and how                                            pipe fittings,
chemicals as volatile liquid anesthetics and
                                                           employees can obtain and use the available                                           use Teflon tape.
compressed medical gases. However, containers
                                                           hazard information.                                                                  Do not use
of other chemicals not under the jurisdiction
                                                        The physical and health hazards of the                                                 this tape on
of the FDA must be labeled, tagged or marked
                                                           chemicals in the work area.                                                          compression
with the identity of the material and must show
                                                        Measures employees can take to protect                                                 fittings.
appropriate hazard warnings as well as the
name and address of the chemical manufacturer,             themselves from these hazards, including
importer, or other responsible party. The hazard           specific procedures put into effect by the
warning can be any type of message – words,                employer to provide protection such as
pictures, or symbols – that conveys the hazards            engineering controls, appropriate work
of the chemical(s) in the container. Labels must           practices, emergency procedures for spill
be legible, in English (plus other languages if            containment, and the use of personal
desired), and prominently displayed.                       protective equipment.
                                                        Methods and observations that may be used
                                                           to detect the presence or release of anesthetic
Elite CME                                                                                                                                                  Page 41
 3        Select scavenging       Provide a range      8           Repeat procedure in                If personal                          niTRous oxiDE – n2o
          system and mask.        of mask sizes                    step 7.                            exposures are                       Final Examination Exercises
          Mask should come        for patients.                                                       less than 150                     Choose True or False for questions
          in various sizes to     Check to see                                                        ppm but greater               1 through 5 and mark your answers on the
          patients. Scavenging    that noise levels                                                   than 25 ppm,                      Final Examination Sheet found on
          systems should          at the mask                                                         implement                         page 109 or take your test online at
          operate at air flow     are acceptable                                                      auxiliary                            www.onlinedentalCE.com.
          rate of 45 lpm.         when the                                                            exhaust
                                  scavenging                                                          ventilation near
                                  system exhaust                                                      the patient’s               1. Long-term exposure to nitrous oxide can
                                  rate is operated                                                    mouth. Capture                 cause reproductive side effects.
                                  at 45 lpm.                                                          distance should
                                                                                                      no greater than                      True               False
 4        Connect mask to         Determine
          hose and turn on        proper vacuum                                                       10 inches from
          vacuum pump before      pump size for                                                       the patient’s               2. The National Institute for Occupational
          turning on N2O.         maintaining 45                                                      nose and                       Safety and Health recommended, in
          Scavenging system       lpm flow rates,                                                     mouth area and                 a technical report published in 1977,
          vacuum pump must        especially when                                                     exhaust no less                controlling exposure limits of nitrous
          have capacity to        interconnected                                                      than 250 cfm                   oxide waste to 35 parts per million (ppm)
          scavenge 45 lpm per     with other                                                          at the hood                    of air during dental surgery.
          dental operation.       dental                                                              opening. Avoid
                                                                                                      getting between                      True               False
                                  systems. If                                                         the auxiliary
                                  undersized,                                                         exhaust hood                3. Inhaled anesthetic agents include two
                                  replace pump.                                                       and patient’s                  different classes of chemicals.
                                                                                                      mouth and nose
 5        Place mask on           Secure mask                                                         area.                                True               False
          patient and assure a    with “slip”
          good, comfortable       ring for “good      Conclusion                                                                  4. Venting waste anesthetic gas via the
          fit. Make sure          activity”           Nitrous oxide is used in many dental and                                       exhaust grille or exhaust duct of a non-
          reservoir bag is not    from patient        medical offices and should be used with care.                                  recirculating ventilation system is an
          over- or under-         breathing.          It is the most frequently used sedation method                                 example of an active system.
          inflated while the                          used in dentistry. All bodily functions remain
          patient is breathing.                       normal, and the patient is able to breathe on                                        True               False
 6        Check general           If smoke from       his/her own. The patient will not fall asleep
          ventilation for         smoke tubes         and will not have memory loss. It is best used                              5. Three fundamental types of air samples
          good room air           indicate room       for mildly anxious patients who wish only a                                    can be taken to evaluate the workplace;
          mixing. Exhaust         air mixing          small amount of sedation to “take the edge                                     they are personal, area and source
          vents should not be     is poor, then       off” or to make them less nervous. The patient                                 samples.
          close to air supply     increase the        is able to respond appropriately to physical
          vents (use smoke        airflow or                                                                                               True               False
                                                      stimulation and verbal commands. It is a way
          tubes to observe air    redesign. If        for the dentist to manage pain and anxiety
          movement in room.)      exhaust vents       during dental appointments, but they must
                                  are close to air
                                                      also administer it wisely and with caution.
                                  supply vents,
                                                      Each dental or medical office should establish
                                  relocate (check
                                  with ventilation
                                                      its own comprehensive training program on
                                  engineers           how to maintain the equipment and proper
                                  to make             safety standards. This course should help you
                                  adjustments).       to review your office routines and make sure
                                                      you are setting the way to achieve the best
     7    Conduct personal        If personal
                                                      safety standards for your patients and for your
          sampling of dentist     exposures
          and dental assistant    exceed 150          employees.
          for N2O exposure.       ppm during          Bibliography
          Use diffusive           administration,     s“Nitrous oxide and its abuse”; Theodore J. Jastak, Journal of the
                                                      American Dental Association, 1991. Abstract accessed Sept. 15, 2010,
          sampler or infrared     improve             at http://www.faqs.org/abstracts/Health/Nitrous-oxide-and-its-abuse-
          gas analyzer (see       mask fit and        Quantification-and-analysis-of-pain-in-nonsurgical-scaling-and-or-root-p.
          sampling methods).      make sure it        s“46 Health Care Professionals Linked to Substance Abuse,” Bristol
                                  is secure over      Herald Courier, April 26, 2009.
                                                      sFederation of State Physician Health Programs. http://www.fsphp.org.
                                  the patient’s       sNitrous Oxide-Oxygen: A New Look at a Very Old Technique; Stanley
                                  nose. Minimize      F. Malamed, DDS, and Morris S. Clark, DDS. Journal of the California
                                                      Dental Association. 2003
                                  patient talking
                                  while N2O is

Page 42                                                                                                                                                                Elite CME
CHAPTER 3 - niTRous oxiDE – n2o
Figures 1 through 7 in chapter

Figure 1                          Figure 5

                                  Figure 6
Figure 2

Figure 3

                                  Figure 7

Figure 4

Elite CME                                    Page 43
                   CHAPTER 4                           – a burden of disease that restricts activities in    The standard definition of health, “freedom
oRAL HEALTH AnD oRAL PHARyngEAL school, work and home, and often significantly                               from disease, defect, or pain,” defines what
                                diminishes the quality of life.                                              health is not, rather than what it is. A more
                                                                                                             positive definition, one that the World Health
                  (5 CE HouRs)                         The word oral, both in its Latin root and in
                                                                                                             Organization established in 1948, states that
Learning objectives                                    common usage, refers to the mouth. The
                                                                                                             health is a complete state of physical, mental,
!   Define the term oral health.                       mouth includes not only the teeth and the gums
                                                                                                             and social well-being, and not just the absence of
!   Study the parts of the mouth affected by oral      (gingiva) and their supporting connective tissues,
    cancer.                                            ligaments and bone, but also the hard and soft
!   Review the different types of cancer, benign       palate, the soft mucosal tissue lining of the mouth   The broadened meaning of oral health parallels
    and malignant.                                     and throat, the tongue, the lips, the salivary        the broadened meaning of health. In 1948,
!   List the major risk factors of oral cancer.        glands, the chewing muscles and the upper and         the World Health Organization expanded the
!   Identify the signs and symptoms.                   lower jaws, which are connected to the skull by       definition of health to mean “a complete state
!   Describe the possible treatments and side          the temporomandibular joints. Equally important       of physical, mental and social well-being, and
    effects.                                           are the branches of the nervous, immune and           not just the absence of infirmity.” It follows that
                                                       vascular systems that animate, protect and            oral health must also include well-being. Just as
introduction                                           nourish the oral tissues, as well as provide the      we now understand that nature and nurture are
In 2008, in the United States alone, about 34,000      connections to the brain and the rest of the body.    inextricably linked, and mind and body are both
individuals were diagnosed with oral cancer.           The genetic patterning of development in utero        expressions of our human biology, so, too, we
Statistics show that 66 percent of the time, these     further reveals the intimate relationship of the      must recognize that oral health and general health
will be found as a late stage three or four disease.   oral tissues to the developing brain and to the       are inseparable. We ignore signs and symptoms
The term oral cancer includes cancers of the           tissues of the face and head that surround the        of oral disease and dysfunction to our detriment.
mouth and the pharynx, part of the throat. About       mouth, structures whose location is captured in
two-thirds of oral cancers occur in the mouth and                                                            Consequently, a second theme of the report is
                                                       the word craniofacial.
about one-third are found in the pharynx. Oral                                                               that oral health is integral to general health. You
cancer will be diagnosed in an estimated 35,000        A major theme of this course is that oral health      cannot be healthy without oral health. Oral health
Americans this year and will cause approximately       means much more than healthy teeth. It means          and general health should not be interpreted
7,500 deaths. Oral cancer can spread quickly.          being free of chronic oral-facial pain conditions,    as separate entities. Oral health is a critical
On average, 60 percent of those with the disease       oral and pharyngeal (throat) cancers, oral soft       component of health and must be included in
will survive more than five years. Oral cancer         tissue lesions, birth defects such as cleft lip and   the provision of health care and the design of
most often occurs in people over the age of 40         palate, and scores of other diseases and disorders    community programs.
and affects more than twice as many men as             that affect the oral, dental and craniofacial
                                                                                                             The wider meanings of oral and health in no way
women. Low public awareness of the disease is          tissues, collectively known as the craniofacial
                                                                                                             diminish the relevance and importance of the two
a significant factor, but these cancers could be       complex. These are tissues whose functions we
                                                                                                             leading dental diseases, caries (tooth decay) and
found at early, highly survivable stages through       often take for granted, yet they represent the very
                                                                                                             the periodontal diseases. They remain common
a simple, painless, five-minute examination by a       essence of our humanity. They allow us to speak
                                                                                                             and widespread, affecting nearly everyone at
trained medical or dental professional.                and smile; sigh and kiss; smell, taste, touch,
                                                                                                             some point in the life span. What has changed is
                                                       chew and swallow; cry out in pain; and convey
Scientists are studying oral cancer to learn more                                                            what we can do about them.
                                                       a world of feelings and emotions through facial
about this disease, and doctors are exploring new      expressions. They also provide protection against     At the start of the 20th century, most Americans
ways to treat it. This research keeps increasing       microbial infections and environmental insults.       expected to be toothless by age 45, and most
our knowledge about oral cancer.                                                                             were. Expectations have changed, and most
                                                       The craniofacial tissues also provide a useful
Oral health means more than healthy teeth and                                                                people now assume that they will maintain their
                                                       means to understanding organs and systems in
the absence of disease. It involves the ability of                                                           teeth over their lifetime and take active measures
                                                       less accessible parts of the body. The salivary
individuals to carry out essential functions such                                                            to do so. Researchers in the 1930s discovered
                                                       glands are a model of other exocrine glands, and
as eating and speaking as well as to contribute                                                              that people living in communities with naturally
                                                       an analysis of saliva can provide telltale clues
fully to society. The meaning of oral health                                                                 fluoridated water supplies had fewer dental
                                                       of overall health or disease. The jawbones are
has developed in tandem with progress in                                                                     caries than people drinking unfluoridated water.
                                                       examples of other skeletal parts. The nervous
understanding the two chief dental diseases –                                                                But not until the end of World War II were the
                                                       system apparatus underlying facial pain has its
dental caries and periodontal diseases – which                                                               investigators able to design and implement the
                                                       counterpart in nerves elsewhere in the body.
historically have been the major preoccupation                                                               community clinical trials that confirmed their
of patients, providers and research investigators      A thorough oral examination can detect signs of       observations and launched a better approach to
alike. There is a marvelous success story here         nutritional deficiencies as well as a number of       the problem of dental caries: prevention. Soon
regarding the prevention of oral cancer and how        systemic diseases, including microbial infections,    after, adjusting the fluoride content of community
it can be detected early. These investigations         immune disorders, injuries and some cancers.          water supplies was pursued as an important
were complemented by studies of the tissues of         Indeed, the phrase “the mouth is a mirror” has        public health measure to prevent dental caries.
the mouth and adjacent areas – the craniofacial        been used to illustrate the wealth of information
                                                                                                             Although this measure has not been fully
complex.                                               that can be derived from examining oral tissues.
                                                                                                             implemented, the results have been dramatic.
Great progress has been made in reducing the           New research is pointing to associations              Dental caries began to decline in the 1950s
extent and severity of common oral diseases, and       between chronic oral infections and heart and         among children who grew up in fluoridated cities,
recent history has seen marked improvements            lung diseases, stroke, and low birth-weight           and by the late 1970s, declines in decay were
in the nation’s oral and dental health, thanks         and premature births. Associations between            evident for many Americans. The application of
to successful prevention measures adopted              periodontal disease and diabetes have long been       oral science to improved diagnostic, treatment
by communities, individuals and oral health            noted. This course assesses these associations and    and prevention strategies has saved billions of
professionals. However, not everyone is                explores mechanisms that might explain these          dollars per year in the nation’s annual health bill.
experiencing the same degree of improvement.           oral-systemic disease connections.                    Even more significant, the result is that far fewer
What amounts to a silent epidemic of dental and                                                              people are edentulous (toothless) today than a
                                                       In parallel with the broadened meaning of oral
oral diseases is affecting some population groups                                                            generation ago.
                                                       health, the meaning of health has evolved.

Page 44                                                                                                                                                Elite CME
The theme of prevention gained momentum as             systems to study normal function and diagnose        molecules to plug gaps between them and further
pioneering investigators and practitioners in the      disease. They are completing the mapping and         impede penetration by damaging chemicals or
1950s and 1960s showed that not only dental            sequencing of human, animal, microbial and           microorganisms. Still another type of oral mucosa
caries but also periodontal diseases are bacterial     plant genomes, the better to understand the          forms the pebbly surface of the back and sides
infections. The researchers demonstrated that the      complexities of human development, aging and         of the tongue. Lining the depths of these surface
infections could be prevented by increasing host       pathological processes. They are growing cell        “papillae” are the taste buds.
resistance to disease and reducing or eliminating      lines, synthesizing molecules and using a new
                                                                                                            Interestingly, the epithelium that lines the
the suspected microbial pathogens in the oral          generation of biomaterials to revolutionize tissue
                                                                                                            gingival surface completely lacks a keratin layer,
cavity. The applications of research discoveries       repair and regeneration. More than ever before,
                                                                                                            yet this “naked” epithelium lies next to one of
have resulted in continuing improvements in the        they are working in multidisciplinary teams to
                                                                                                            the most dense concentrations of bacteria to be
oral health of Americans, new approaches to the        bring new knowledge and expertise to the goal
                                                                                                            found in the body. Thus there is an opportunity
prevention and treatment of dental diseases, and       of understanding complex human diseases and
                                                                                                            for infectious agents or their byproducts to
the growth of the science.                             disorders.
                                                                                                            penetrate the naked epithelial barrier and initiate
The significant role that scientists, dentists,        The mouth                                            an inflammatory response, as happens in gingival
dental hygienists and other health professionals       The mouth is the gateway to the body, performing disease.
have played in the prevention of oral disease and      dozens of functions that place high demands          Special cells in the basal layer of the oral
disability leads to a third theme of this report:      on its unique hard and soft tissues. The point of    mucosa generate replacements for surface cells
safe and effective disease prevention measures         entry is the lips, which open into the oral cavity.  as they wear out. The painful oral ulcers and
exist that everyone can adopt to improve oral          The cheeks form the sides of the cavity, and the     oral mucositis that may develop in patients
health and prevent disease. These measures             roof is formed by the palate, which separates        undergoing radiation or chemotherapy for head
include daily oral hygiene procedures and              the mouth from the nose above and the pharynx        and neck cancer occur because these cancer-
other lifestyle behaviors, community programs          (throat) behind. The anterior palate is hard,        killing agents attack all cells undergoing rapid
such as community water fluoridation and               formed by underlying bone, and serves as a           turnover, whether healthy or cancerous.
tobacco cessation programs, and provider-based         shield against trauma to the face and head. The
interventions such as the placement of dental          posterior palate is soft, composed of muscles        The teeth
sealants and examinations for common oral and          and connective tissue that blend into the walls      The most prominent features of the oral cavity
pharyngeal cancers. It is hoped that this surgeon      of the pharynx. Hanging from the rear of the         are the teeth. The 20 primary, or deciduous, teeth
general’s report will facilitate the maturing of the   soft palate is the uvula, a mass of muscle and       erupt generally between 6 months and 2 to 3
broad field of craniofacial research so that gains     connective tissue. Under the tongue is the floor     years of age and are succeeded by the permanent
in the prevention of craniofacial diseases and         of the mouth, composed primarily of muscle and       teeth beginning at about age 6. The primary
disorders can be realized that are as impressive as    salivary glands. The paired tonsils and adenoids,    teeth enable infants to eat solid foods, aid speech
those achieved for common dental diseases.             important components of the immune system,           development, and serve as placeholders for the
                                                       lie at the sides of the palate and within the        permanent dentition. Keeping primary teeth
At the same time, more needs to be done to
                                                       nasopharynx, respectively.                           healthy is important, not only in sparing an
ensure that messages of health promotion and
                                                                                                            infant pain and disease, but also in preserving the
disease prevention are brought home to all             The pharynx opens into channels leading either
                                                                                                            dimensions of the dental arches and lessening
Americans. In this regard, a fourth theme of the       to the lungs for respiration or the esophagus for
                                                                                                            the risk of dental caries in the permanent teeth. A
report is that general health risk factors, such       further digestion and passage to the stomach.
                                                                                                            period of mixed primary and permanent dentition
as tobacco use and poor dietary practices, also        This is a point of vulnerability, where food or
                                                                                                            occurs from about ages 6 to 13. There are 28 to
affect oral and craniofacial health. The evidence      other obstructions can lodge in the airway and
                                                                                                            32 permanent teeth, depending on whether the
for an association between tobacco use and oral        lead to death by asphyxiation.
                                                                                                            four wisdom teeth (third molars), which are last
diseases has been clearly delineated in almost
                                                       Externally, the oral cavity is bounded by the        to erupt, are present. Teeth are anchored in the
every surgeon general’s report on tobacco since
                                                       maxilla (the upper jaw bone), attached to the        jaws by the periodontal ligament. This ligament
1964, and the oral effects of nutrition and diet
                                                       cranium, and the mandible (the lower jaw),           connects the cervix (neck) of the tooth, at the
are presented in the surgeon general’s report on
                                                       attached to the temporal bone of the skull by the    junction between the crown and root, to the
nutrition (1988). All the health professions can
                                                       temporomandibular joint.                             gingiva. Below that, the ligament connects the
play a role in reducing the burden of disease in
                                                                                                            outer layer of the tooth root, the cementum, to the
America by calling attention to these and other        The oral mucosa                                      adjacent alveolar bone (the part of the jaw bone
risk factors and suggesting appropriate actions.       Except for the teeth, the oral tissues are covered
                                                                                                            that supports the tooth roots).
Clearly, promoting health and preventing disease       by a mucous membrane called the oral mucosa,
                                                       which varies in color from pink to brownish          The evolutionary forces that shaped the human
are concepts the American people have taken
                                                       purple, depending on an individual’s skin color.     mouth designed an apparatus for optimal food
to heart. For the third decade, the nation has
developed a plan for the prevention of disease         Like skin, the oral mucosa acts as a major barrier intake. The front four upper and lower incisor
and the promotion of health, embodied in the           against chemical irritants and mechanical forces; teeth are chisel-shaped for biting, cutting, and
U.S. Department of Health and Human Services           it can even withstand temperatures that would be tearing and exert forces of 30 to 50 pounds.
                                                       painful to the skin. In areas subject to chewing     The canines, or cuspids, are larger and stronger
(2000) document, Healthy People 2010. As a
                                                       forces and food movements, the surface layer is      and have deeper roots than the incisors; their
nation, we hope to eliminate disparities in health
and prevent oral diseases, cancer, birth defects,      relatively hard, composed of epithelial cells filled conical cusps are effective for ripping and
                                                       with insoluble keratin, the fibrous protein found    tearing. The premolars, or bicuspids, and the
AIDS and other devastating infections; mental
illness and suicide; and the chronic diseases of       in skin, nails, hair, and animal horn. Elsewhere – molars are designed for heavy grinding and
                                                       in the mucosal lining of the cheeks, for example     chewing, exerting forces as high as 200-plus
aging. To live well into old age free of pain and
                                                       – the surface layers are softer and more flexible,   pounds. The temporomandibular joint, the most
infirmity and with a high quality of life is the
American dream.                                        enabling the mobility we need to speak, chew and complex synovial joint in the body, equips the
                                                       make facial expressions. To aid in their barrier     human jaw with extraordinary mobility, enabling
Scientists today take that dream seriously in          function, surface mucosal cells are square-          movements in three dimensions. Its range of
pursuing the intricacies of the craniofacial           shaped and closely juxtaposed, with specialized      motion is controlled by three sets of muscles
complex. They are using an ever-growing array          organelles and cell products that promote cell-cell of mastication – the masseter, temporalis, and
of sophisticated analytic tools and imaging            adherence. The cells can also secrete sticky         pterygoid muscles. Chewing reduces food to
Elite CME                                                                                                                                              Page 45
small particles and mixes it with saliva to form a      inhibitor (SLPI), recently discovered to have the     the diffusion of acids into the teeth and the
bolus for swallowing.                                   ability to inhibit HIV from invading cells.           dissolution of tooth mineral.
The salivary glands                                     The ability of saliva to limit the growth of          The immune system
Saliva is the mixed product of multiple salivary        pathogens, in some instances even preventing          The salivary glands and the oral mucosa, along
glands that lie under the mucosa. The three major       them from establishing a niche in the biofilm         with the body’s other mucosal linings and
glands are the paired parotid, submandibular and        community in the first place, is a major              the lymphatic circulation, constitute a major
sublingual glands. The parotids, near the ears,         determinant of general as well as of oral health.     component of the body’s defense system – the
secrete a watery saliva into the mouth via ducts        When salivary flow is compromised, the gateway        mucosal immune system. When the area of
in the cheeks. The walnut-sized submandibular           to the body can open wide to local as well as to      the oral mucosa is combined with the areas of
glands lie in the floor of the mouth and secrete        systemic pathogens.                                   the mucosal linings and passageways of the
a mucous fluid. The secretions of the almond-                                                                 respiratory, gastrointestinal, urinary, and genital
                                                        Barrier and buffering properties
shaped sublingual glands, also in the floor of the                                                            tracts, the total represents the largest surface area
                                                        Salivary components protect oral tissues in other
mouth but near the front, usually join with those                                                             of the body – nearly 400 square meters, or 200
                                                        ways as well. Mucins have unique properties
of the submandibular glands. Tiny minor salivary                                                              times larger than the total skin area.
                                                        that enable them to concentrate on mucosal
glands are scattered within the inner surfaces of
                                                        surfaces and provide an effective barrier against     The great majority of infectious diseases affect or
the lips, cheeks and soft and hard palates; these
                                                        drying and physical and chemical irritants.           are acquired through mucosal surfaces. Immune
secrete a mucinous saliva directly onto the soft
                                                        They act as natural waterproofing, control the        cells that line the mucous membranes throughout
tissue surfaces.
                                                        permeability of the tissue surfaces and help limit    the body secrete antibodies targeted to specific
Saliva moistens food and provides mucinous              penetration of potential irritants and toxins in      disease-causing microbes. The mucosal immune
proteins to lubricate the bolus for ease of             foods and beverages, as well as toxic chemicals       system works in concert with the blood-borne
swallowing. The combined movements of the               and potential carcinogens in tobacco and tobacco      immune system to detect and dispose of foreign
tongue and cheeks move the bolus to the back            smoke and from other sources. This barrier            substances and invading microbes.
of the mouth. Saliva also contains the enzyme           function complements the barrier formed by the
                                                                                                              The two components of the immune system
amylase, which initiates the digestion of starch.       oral mucosa itself. The mucosa has a specific
                                                                                                              consist of molecules and cells that provide both
By solubilizing food components and facilitating        permeability coefficient that can change under
                                                                                                              broad and specific defense mechanisms. In the
their interaction with the taste buds on the            various conditions of stress, nutritional status,
                                                                                                              broad group are some circulating white blood
tongue and palate, saliva also contributes to taste     and other challenges.
                                                                                                              cells (monocytes and granulocytes) associated
                                                        Saliva contains several effective buffering           with the inflammatory response. These cells
Tissue protection                                       systems that can help maintain a normal pH            migrate to a site of injury or infection and move
The main function of saliva is not – as is              when acidic foods and beverages are introduced,       into damaged tissues manifesting the four signs
commonly believed – to aid digestion, but to            thereby protecting oral tissues against acidic        of inflammation: swelling, heat, redness and pain.
protect the integrity of the oral tissues. The          attack. When swallowed, these buffers protect the     The cells promote an increase in blood flow to
moment a baby passes through the birth canal and        esophagus, helping neutralize the reflux acids of     begin the healing process, and they recruit other
takes its first breath, microbes begin to take up       conditions such as heartburn and hiatal hernia.       cells able to engulf and dispose of the offending
residence in its mouth. Later, as the teeth erupt,                                                            organism.
                                                        Wound healing
additional bacteria establish colonies on tooth                                                               The specific immune system is associated with
                                                        Saliva also contains molecules that nurture and
surfaces. Nearly 500 species of microbes in all,                                                              two major classes of immune cells: T cells and B
                                                        preserve the oral tissues, even helping them
most of which are not harmful, will colonize                                                                  cells. T cells react to antigens (proteins associated
                                                        to repair and regenerate. Experimental studies
the oral cavity. The microbes form a biofilm, in                                                              with microbes or irritants) and can stimulate
                                                        have shown that wound healing is significantly
which their numbers greatly exceed the number                                                                 B cells to make antigen-specific antibodies.
                                                        enhanced by saliva, in part because of the
of human inhabitants on Earth.                                                                                These are the Y-shaped molecules called
                                                        presence of a potent molecule, epidermal growth
Millions of years before there were toothbrushes,       factor (EGF). When swallowed, EGF can also            immunoglobulins.
dental floss and water irrigators, evolutionary         protect the tissue surfaces of the esophagus.         T cells are the instruments of cell-mediated
forces generated protective mechanisms to               Vascular endothelial growth factor (VEGF) has         immunity; they are able to detect telltale surface
combat potentially harmful microbes. The                also been identified in saliva. VEGF stimulates       markers on diseased or foreign cells that
physical flow of saliva helps to dislodge               blood vessels and may contribute to the               distinguish them from normal body cells. Some
pathogens (viruses, bacteria and yeast) from            remarkable healing capacity of oral tissues.          T cells can kill infected cells and cancer cells
teeth and mucosal surfaces, just as tearing                                                                   directly. T cells are also involved in the rejection
and blinking, sneezing and coughing and
                                                        Caries protection
                                                        Saliva also guards against dental caries (tooth       of organ transplants.
expectorating clear the eye, nose and throat.
                                                        decay), the disease that has been the greatest        Certain T cells are memory cells, preserving the
Saliva can also cause microbes to clump together
                                                        threat to teeth. Caries is caused by bacteria that    information from earlier encounters with specific
so that they can be swallowed before they
                                                        generate acids that attack tooth mineral. The         pathogens. Thus they are able to initiate more
become firmly attached. Saliva can destroy orally
                                                        buffering systems in saliva, augmented by the         rapid and effective responses in the event of a
shed infected white blood cells by virtue of its
                                                        neutralizing components urea and ammonium,            repeat encounter with the pathogen. Helper T
low salt content: the infected cells – of higher salt
                                                        counter the acid formation. The physical flow         cells assist in activating killer T and B cells. It is
content – swell and burst when exposed to fluids
                                                        of saliva also helps flush out sugars and food        the loss of helper T cells that leads to the many
of lower salinity.
                                                        particles that are the bacterial food source.         infections that cause illness and death in HIV
Salivary secretions, like tears and other exocrine      Mineral salts in saliva – calcium and phosphate       disease. Still another group of T cells, suppressor
gland secretions, are rich in antimicrobial             – can remineralize tooth enamel, effectively          T cells, moderates the activities of both B and T
components. Certain molecules in saliva, such as        reversing the decay process. This regenerative        lymphocytes.
lysozyme, lactoferrin, peroxidase and histatins,        function is greatly enhanced by the presence of
can directly kill or inhibit a variety of microbes;     fluoride in saliva. Finally, saliva forms a film on   Activated T cells generate and release cytokines
the histatins are particularly potent antifungal        teeth made up of selectively adsorbed proteins        – potent families of proteins, such as the
agents. Several salivary proteins exhibit antiviral     that have a high affinity for tooth mineral.          interleukins, that can stimulate immune cells to
properties, including secretory leukocyte protease      This acquired pellicle is insoluble and limits        divide, migrate, attack and engulf invaders or

Page 46                                                                                                                                                   Elite CME
participate in the inflammatory response. Other      and systems in place are being unfolded at             During the formation of the midbrain and
cytokines include varieties of tumor necrosis        the molecular level. Families of master and            hindbrain, cranial neural crest cells migrate into
factor and adhesins (proteins that facilitate the    regulatory genes have been identified, and their       the developing facial areas and differentiate
binding of immune cells to each other or to blood    role in controlling how the body’s general shape       into neuronal and nonneuronal tissues. The
vessel linings). Feedback mechanisms provide         and specialized tissues and organs are formed is       neuronal tissues include the clusters of nerve
a system of checks and balances to regulate          coming to light.                                       cells (ganglia) that lie adjacent to the spinal
cytokine production.                                                                                        cord, parts of the ganglia of four cranial nerves,
                                                     Early development                                      and two of the meningeal layers of the brain.
The immune system interacts with the nervous         The three-germ cell layers                             The nonneuronal tissues include major bones,
and endocrine systems. For example, immune           By the time the face and the mouth are ready to        cartilage, the dentin and cementum of teeth, and
cytokines secreted into the brain can induce         form, the human embryo is in the third week of         the various types of connective tissues of the
the fever associated with infection: the high        development. The embryo has evolved from a             craniofacial complex, as well as the muscles of
temperature may help destroy the infectious          sphere to an oval, two-layered disk with a head-       the eye. The branchial arches give rise to the
agent. The brain’s response to stress also has       to-tail orientation. The outer layer is the epiblast   bones, cartilage, nerves, muscles, and blood
repercussions for the immune system. The             and will become the ectodermal germ layer.             supply of successive segments of the head and
hypothalamus pituitary-adrenal axis is a major       A narrow groove, called the primitive streak,          neck.
pathway activated in response to stress, which       extends from the tail toward the center of the
results in the secretion of cortisol, the stress     disk, where it ends in a spot surrounding a small      The face and mouth
hormone, from the adrenal glands. Cortisol           depression called the primitive pit. Epiblast cells    The branchial arches play a key role in the
promotes the body’s fight-or-flight mechanisms,      migrate toward the streak and pit, detach from         formation of the facial structures. Toward the
but via feedback loops, cortisol acts to depress     the surface and slip downward to form the two          end of the fourth week of gestation, a primitive
immune reactions.                                    additional germ-cell layers, the mesoderm and,         mouth appears. This “stomadeum” is flanked by
Much of what we know about the immune system         below that, the endoderm.                              a series of swellings, or prominences, derived
has come from studies of serum factors, but                                                                 from the first pair of branchial arches. A single
                                                     The ectodermal layer gives rise to tissues that
research in the last two decades has generated                                                              frontonasal prominence forms the upper border of
                                                     relate the body to the outside world: the nervous
much new information about mucosal immunity.                                                                the stomadeum. On either side of this prominence
                                                     system; the sensory epithelium of the ears,
The mucosal immune system can be divided                                                                    are two thickened regions of ectoderm – the nasal
                                                     nose, and eyes; skin, hair, nails, salivary glands,
into inductive and effector compartments. The                                                               placodes. At the sides of the stomadeum and
                                                     tonsils and tooth enamel; and the pituitary,
nasal-associated lymphoreticular tissues (NALT)                                                             below it are pairs of maxillary and mandibular
                                                     mammary and sweat glands. At the head end,
in the nasopharyngeal area (which includes the                                                              prominences.
                                                     the mesodermal layer gives rise to a primitive
tonsils) and the gut-associated lymphoreticular      connective tissue, called mesenchyme, which            In the course of the next three weeks, differential
tissues (GALT) in gut tissue are inductive regions   will interact with the ectoderm to form parts of       growth and movements of the various
where foreign invaders are encountered. If, for      the head and mouth. The remaining mesoderm             prominences and fusions of tissues that come
example, infectious bacteria are swallowed,          develops into the muscle, cartilage, bone and          together at the midline will sculpt the bridge,
they can stimulate immune cells in GALT to           subcutaneous skin tissue of the rest of the body.      crest, sides and tip of the nose, the upper and
circulate T and B cells through the lymph system     The mesoderm is also the origin of the vascular        lower lips and the upper and lower jaws.
to various effector sites in the gastrointestinal    and urogenital systems (except for the bladder),       The external merger at the midline of a pair
and upper respiratory tracts and in the salivary     the spleen and the adrenal cortex. The innermost,      of prominences that helps to form the nose
and other exocrine glands. The B cells in the        endodermal layer provides the linings of the gut,      occurs inside the mouth as well, resulting in an
gland produce antibodies, designated S-IgA, to       the respiratory system, bladder, liver, pancreas,      intermaxillary segment that will contribute to the
which is attached a secretory component. These       thyroid and parathyroid glands, and parts of the       formation of the four upper incisors and parts of
antibodies are the dominant type found in saliva,    middle ear.                                            a small triangular-shaped primary palate and the
tears, breast milk and colostrum and in the
                                                     neural tube and neural crest                           upper jaw. The bulk of the palate, the secondary
gastrointestinal and genitourinary tracts.
                                                     Further migrations and descending movements            palate, forms from shelflike outgrowths of the
The uses of the mucosal immune system extend         of cells result in the formation of the notochord,     maxillary prominences. These growths appear in
beyond its normal surveillance and defense           a solid cord of cells along the midline that will      the sixth week, and in the following week fuse
functions. The tissues can be used as routes for     become the backbone. The ectoderm above the            along the midline above the tongue. (The tongue
delivery of oral (swallowed) or nasal (inhaled)      notochord next thickens to form a neural plate.        appears at approximately four weeks, the front
vaccines, as sites for gene transfer to augment      The sides of the plate curve up and inward to          two-thirds forming from the first branchial arch
host defenses, and as a means of invoking oral       form a neural tube, beginning at the head, with        and the posterior third from parts of the second,
tolerance – the suppression of overactive or         fusion completed by the end of the fourth week.        third and fourth branchial arches.) The palatal
inappropriate immune responses that occur in         The tail end of the tube will form the spinal cord;    shelves also fuse with the primary palate along
chronic inflammatory and autoimmune diseases.        the head end differentiates into the three parts of    a triangular border called the incisive foramen.
                                                     the primitive brain: the forebrain, midbrain and       This border is considered the line of division
Craniofacial origins
                                                     hindbrain.                                             among clefting abnormalities. Lateral cleft lip,
The extraordinary successes of research in
                                                                                                            cleft upper jaw, and clefts between the primary
molecular genetics over the past decade, coupled     What happens next is of central importance to the      and secondary palates are associated with defects
with the National Institutes of Health’s project     craniofacial complex: Cells that were at the edges     anterior to the incisive foramen. Cleft palate and
to map and sequence the human genome, have           of the neural plate break away to form neural          cleft uvula occur because of defects affecting
proved to be a boon in understanding craniofacial    crest cells, which migrate to the forebrain area       closure of the palatal shelves posterior to the
development. The use of automated gene-              and to the nearby branchial arches, a series of        foramen.
sequencing equipment, the Internet availability      swellings on either side of the embryo adjacent to
of genome databases and the ability to transfer      the hindbrain. The hindbrain becomes organized         The teeth
genes or create “knockout” animals – in which        into eight rhombomeres, segments of future nerve       Tooth development begins in the sixth week
a gene of interest has been eliminated – have        tissue arranged in an orderly fashion so that the      with the appearance of an epithelial band lining
greatly facilitated progress. The events that        first two rhombomeres innervate branchial arch 1,      the upper and lower jaws. A part of the band
govern the transformation of a fertilized human      and so on.                                             develops into a dental lamina, which forms a
egg cell into a healthy newborn with all organs
Elite CME                                                                                                                                               Page 47
series of projections into the jaw. These are          In the course of evolution, mammals have                 a premature closure of the bones that form the
the tooth buds and correspond to the sites of          developed four overlapping sets of positional            skull.
deciduous teeth. The epithelial tissue of the bud      memory gene clusters homologous to the fly’s
                                                                                                                The aging of craniofacial tissues
develops into an enamel organ that forms a cap         single hom complex. The four mammalian
                                                                                                                Normal aging describes the developmental
over tissue that is differentiating in the jaw to      hox gene families are ordered in a similar
                                                                                                                processes that begin at conception, continue in
become the dental papilla. The two structures –        anterior-posterior fashion along four different
                                                                                                                childhood and merge gradually into maturation
the enamel organ, derived from the epithelium,         chromosomes. The mammalian genes appear to
                                                                                                                and senescence. The milestones of development
and the dental papilla, derived from neural crest      operate like the hom genes: they code for DNA-           such as the age when children teethe, begin to
mesenchyme – constitute the tooth germ.                binding proteins that control gene expression.           walk, talk, enter puberty, attain their full height
With further development, the tooth germ               The similarity from fly to human is particularly         and so on, are under genetic and hormonal
assumes a bell shape and separates from the            evident when maps of the expression domains of           controls, subject to important environmental
oral epithelium. At the same time, the internal        hom genes in anterior segments of the fly embryo         factors such as nutrition and exercise. Despite the
epithelial layer of the enamel organ undergoes         are compared to maps of hox gene expression as           complexity and interrelationships of the variables
a series of infoldings that will shape the future      seen in the rhombomeres and branchial arches of          involved, a reasonably accurate picture of normal
crown of the tooth.                                    mammals.                                                 age-related changes in the craniofacial complex
Mineralization of the tooth begins at the late         Molecular genetic studies of flies and other             is emerging.
bell stage. The first mineralized tissue to form       nonmammalian species show some variation                 Barring major illness or injury, destructive
is dentin, which provides the foundation for the       in how and when the basic body patterns and              behaviors or severe or unusual environmental
deposition of enamel. The differentiation of the       repeating segments are formed. Sometimes the
                                                                                                                circumstances, the cells, tissues and fluids of the
odontoblasts (the dentin-producing cells) depends      head-to-tail pattern is laid down in the egg cell
                                                                                                                face and mouth are hardy survivors, eminently
on organizing influences from enamel organ cells.      before fertilization – dictated by egg polarity
                                                                                                                durable and functional over a long life span.
Thus the development of these two different hard       genes. Although egg polarity genes do not
                                                       operate in humans, mutations have been found in          For any given individual the combination of
tissues is a mutually dependent process.
                                                       a human gene homologous to the fly egg polarity          life experience and lifestyle (including medical
As dentin is laid down, the odontoblasts move          gene and account for serious syndromes in which          and dental history) creates a unique craniofacial
toward the center of the papilla, trailing thin        there are defects in anterior organs, such as the        portrait, one that inspired George Orwell to
cellular processes, which become embedded in           pituitary gland and heart.                               remark, “By the age of 50, a man gets the face he
the mineralized matrix. When dentin formation is                                                                deserves.”
completed, dentin completely surrounds the pulp,       None of these developmental controls work in
protecting it from injury. The enamel layer of         isolation. Much remains to be understood about           The teeth
the tooth starts to form soon after the first dentin   the genetic clock that determines when and where         One of the more dramatic discoveries in
appears, synthesized by special enamel-forming         developmental genes act, how they interact, and          biomedical science in the 20th century has been
cells, or ameloblasts, which develop from the          what mechanisms are used to sustain as well              the realization that tooth loss is not an inevitable
enamel organ. The tooth root and its outer layer       as terminate their function. The systems that            consequence of aging, but the result of disease
of cementum form only after the crown erupts.          govern programmed cell death are also important:         or injury. Aging does produce a number of other
                                                       normal development depends as much on the                dental changes, however. Teeth change in form
genetic controls                                       elimination of cells as it does on the orderly           and color with age. Wear and attrition alter the
Only in the last decade have scientists begun to       movement, proliferation and differentiation of           biting and chewing surfaces, as do food choices
understand how certain genes and gene families         cells.                                                   and oral habits. The altered surface structure
control embryonic development. Their findings                                                                   produces a different pattern of light reflection in
                                                       When it comes to processes that control the
have come from detailed studies of species                                                                      older teeth, resulting in some yellowing and a
                                                       development of particular tissues or organs –
ranging from fruit flies, nematodes and zebrafish                                                               general loss of translucency. Fully formed enamel
                                                       bones, skin or heart – developmental biologists
to frog, chick, mouse and human embryos. In                                                                     is acellular, hence there is no metabolic activity
                                                       observe that there is often an “organizer,” that
many cases, the simpler organism has been the                                                                   or turnover as occurs in skin, for example. Dentin
                                                       is, a cell or set of cells that initiates the process.   and cementum have limited cellular activity. In
source of discoveries of genes or developmental
                                                       The organizer induces changes in the behavior of         contrast, tooth pulp and periodontal ligament
processes that are highly conserved in the course
                                                       neighboring cells through cell-cell interactions,        undergo relatively high levels of tissue turnover.
of evolution.
                                                       so that these cells develop into the specified type
Research on the fruit fly, for example, has            – bone or skin or heart muscle. The interaction          Tooth surfaces can be eroded by chemical
revealed that particular families of genes are                                                                  dissolution from fruit acids and from acids from
                                                       with the neighboring cell is often in the form of
responsible for the fundamental head to thorax                                                                  sugars in foods such as soft drinks and candies.
                                                       a signaling molecule, such as a growth factor
to tail patterning of the fly’s body. Another set of                                                            This destructive process can occur at any age,
                                                       (e.g., transforming growth factor beta, epidermal
genes determines the back-to-front positioning                                                                  resulting in loss of translucency as well as some
                                                       growth factor, fibroblast growth factor) that            tissue loss from demineralization. Countering
of organs, and a third set subdivides this general
                                                       attaches to a receptor on the surface membrane           the erosive forces are the natural components in
body plan into a series of discrete segments. With
                                                       of the recipient cell. This interaction is translated    saliva that help re-mineralize the enamel surface,
further development, yet another family of genes
confers a positional memory on the cells within a      to the interior of the cell, where a chain of            a process that is enhanced when fluoride is
segment. These “homeotic selector” genes ensure        molecular interactions eventually reaches the            present.
that cells in one part of a particular segment         cell nucleus to effect gene expression. One of the
                                                                                                                The cementum increases in thickness with age.
“know” that they are destined to be wings and          more startling discoveries of the past decade has
                                                                                                                Gingival recession caused by normal aging
not legs, or to be eyes and not antennae. In flies     been the finding that a series of mutations, each
                                                                                                                exposes the cementum to the oral environment
the homeotic genes are known as hom genes.             associated with a change in only one nucleotide          (and is the origin of the expression “long in
Their arrangement on the fly chromosome is             of the gene for the fibroblast growth factor             the tooth”). The exposed cementum can often
ordered with genes at one end of the chromosome        receptor – also called point mutation – accounts         be worn away mechanically, exposing the
specifying the developmental destiny of cells in       for a range of organ defects seen in at least a          underlying dentin, which can then become
the most anterior segments of the fly’s body and       half dozen craniofacial syndromes. Interestingly,        hypersensitive. Dentin responds through a series
genes at the other end specifying the fate of cells    all these syndromes include craniosynostosis,            of protective changes that work to close off the
in the most posterior segments.
Page 48                                                                                                                                                  Elite CME
connections between dentin and nerves in the           of movement of the tongue, jaws and oral-facial         The salivary glands and saliva subserve tasting
pulp, reducing transmission of painful stimuli.        muscles. There is some loss of muscle tone in           and digestive functions and also participate in the
                                                       aging, along with changes in tongue shape and           mucosal immune system, a main line of defense
The jaws                                               function in articulating specific speech sounds.        against pathogens, irritants, and toxins.
The bones of the maxilla and mandible that
                                                       Subtle changes may also occur in preparing food
support the teeth, called the alveolar processes,                                                              Salivary components protect and maintain oral
                                                       for swallowing. As with sensory changes, these
are, like bone elsewhere in the body, subject                                                                  tissues through antimicrobial components,
                                                       developments do not seriously interfere with
to cellular turnover in a coordinated process                                                                  buffering agents and a process by which dental
                                                       motor function in healthy older adults.
of bone resorption and formation. Alveolar                                                                     enamel can be remineralized.
bone is well adapted to mechanical stresses and        The salivary glands                                     oral and pharyngeal cancers and
changes continuously during facial growth, tooth       Studies of normative aging indicate that
eruption, tooth wear and tooth loss. This lifelong     individuals vary in the quantity of “whole”
                                                                                                               precancerous lesions
                                                                                                               In 2000, oral or pharyngeal cancer was diagnosed
adaptation makes orthodontic treatments to             saliva they produce. Whole saliva consists of
                                                                                                               in an estimated 30,200 Americans and caused
reposition teeth in adults possible.                   the secretions of the various salivary glands plus
                                                                                                               more than 7,800 deaths (Greenlee et al. 2000).
                                                       other oral contents, such as cells shed from the
Because the primary function of alveolar bone                                                                  Over 90 percent of these cancers are squamous
                                                       mucosa. These individual patterns are consistent
is to support the teeth, the loss of teeth will lead                                                           cell carcinomas – cancers of the epithelial cells.
                                                       across the life span. In healthy adults, there is no
to bone atrophy, making prosthetic replacements                                                                The most common oral sites are on the tongue,
                                                       diminution in the production of saliva from the
difficult. The rate of bone loss is affected by both                                                           the lips and the floor of the mouth. Oral cancer
                                                       major salivary glands in the course of aging.
local disease such as periodontal disease and                                                                  is the sixth most common cancer in U.S. males
systemic conditions such as osteoporosis.              This constancy may seem surprising given                and takes a disproportionate toll on minorities;
                                                       the morphological changes documented in                 it now ranks as the fourth most common cancer
The oral mucosa                                        aging salivary glands. Both the parotid and the         among African American men. The prominent
The oral mucosa appears to age in much the same        submandibular glands lose between 20 and 30             role of tobacco use, especially in combination
way as skin does. The oral epithelium thins and        percent of their essential tissue volume in the         with alcohol, in causing these cancers is a major
becomes less hydrated, increasing vulnerability        course of aging. The loss primarily affects the         incentive to develop effective health promotion
to injury. The rate of cell division is slower, but    acinar components, the cells that secrete saliva.       and disease prevention efforts.
the basic cell architecture and patterning of cell     Increases in the number of ductal cells and in fat,
types throughout the oral cavity are maintained.                                                               This course is about cancers that occur in the
                                                       vascular, and connective tissues compensate for
It is not certain to what extent these changes                                                                 mouth (oral cavity) and the part of the throat at
                                                       this loss, however – evidence of the remarkable
are a natural consequence of aging; they may                                                                   the back of the mouth (oropharynx).
                                                       functional reserve capacity of the glands, which
be due to altered protein synthesis or lowered         enables them to maintain a stable salivary output       The oral cavity and oropharynx have many parts:
responsiveness to regulatory molecules. They           across the life span.                                      Pictured below are the following parts:
may also be an effect of diminished vascularity,                                                                  Š Lip.
                                                       In contrast, studies of age-related changes in the
which could limit cellular access to oxygen and                                                                   Š Tongue.
                                                       chemistry of salivary secretions suggest that there
nutrients.                                                                                                        Š Salivary glands (glands that make saliva).
                                                       are significant reductions in the concentration
Overall immune system function deteriorates                                                                       Š Floor of the mouth.
                                                       of mucins from the submandibular gland, which
with age, and it is likely that mucosal immunity                                                                  Š Hard palate.
                                                       could result in reduced lubrication and contribute
does as well. Such a decline could result in an                                                                   Š Soft palate.
                                                       to a sensation of mouth dryness. There are also
increased risk of transmission of infectious agents                                                               Š Uvula.
                                                       subtle changes in the protective ability of salivary
                                                                                                                  Š Oropharynx.
across the mucosa and probably contributes to          secretory IgA antibody.
                                                                                                                  Š Tonsils.
delayed wound healing in oral tissues with aging.
                                                       Findings                                                   Š Tongue.
sensory and motor functioning                          Natural selection has served Homo sapiens
                                                                                                               The following picture shows the top of the
The high density of sensory nerve endings in           well in evolving a craniofacial complex with
                                                                                                               mouth and the part of the throat at the back of
the craniofacial tissues and their functional          remarkable functions and abilities to adapt,
                                                                                                               the oropharynx.
abilities are well-preserved in aging. There           enabling the organism to meet the challenges of
may be minor increases in threshold detection          an ever-changing environment. An examination
levels or in judgments of intensity, but, for the      of the various tissues reveals elaborate designs
most part, sensory cells can turn over or have a       that have evolved to serve the basic needs and
built-in reserve capacity that allows for near-        functions of a complex mammal as well as
optimal functioning in aging. The exception is         those that are uniquely human, such as speech.
olfaction, which declines in both men and women        The rich distribution of nerves, muscles and
with age. This decrement in smell may lead to          blood vessels in the region as well as extensive
some dissatisfaction with how foods taste and          endocrine and immune system connections is
increased use of flavor enhancers to compensate.       an indication of the vital role of the craniofacial
But for most people, the ability to enjoy food         complex in adaptation and survival over a long
is not appreciably diminished as time goes by.         life span. In particular, genes controlling the basic
Any dramatic change in sensory function –              patterning and segmental organization of human
complaints of a continued unpleasant taste or          development, and specifically the craniofacial
smell or the sudden complete loss of a sensory         complex, are highly conserved in nature. Mutated
modality – should be taken seriously as a sign of      genes affecting human development have
possible oral or systemic disease or a side effect     counterparts in many simpler organisms.
of medication and not dismissed as a natural           There is considerable reserve capacity or
byproduct of aging.                                    redundancy in the cells and tissues of the
The distribution of motor fibers in the                craniofacial complex, so that if they are properly
craniofacial tissues is also abundant and              cared for, the structures should function well over
sufficiently fine-tuned to allow for a full range      a lifetime.

Elite CME                                                                                                                                                  Page 49
The following picture shows the bottom of the             Tobacco and alcohol                                    virus, is now accepted as an oncogenic virus
mouth and the part of the mouth under the                 Tobacco and alcohol are the major risk factors for     responsible for Burkitt’s lymphoma, occurring
tongue (oral cavity).                                     oral cancers, and their effects have been studied      primarily in Africa, and nasopharyngeal
                                                          for many years. Tobacco contains substances that       carcinoma, occurring primarily in China. HPV
                                                          are frankly carcinogenic or act as initiators or       is a major etiologic agent in cervical cancer,
                                                          promoters of carcinogenesis. Among these are           and has been found in association with oral
                                                          N-nitrosonornicotine, 4-nitroquinoline-N-oxide         cancer as well (Sugerman and Shillitoe 1997).
                                                          and benzpyrene. The most damaging carcinogens          HPV DNA sequences have been found in oral
                                                          are found in the tars of tobacco smoke, but many       precancerous lesions as well as in squamous
                                                          forms of smokeless (spit) tobacco, including           cell carcinomas, and experimental evidence has
                                                          snuff, have been implicated in the development         shown that HPV-16 can be an important cofactor
                                                          of mouth cancer. Other habits that have been           in oral carcinogenesis. Herpes simplex type 1
                                                          related to oral cancer include chewing betel nut       antibodies were demonstrated in patients with
                                                          in the presence of tobacco, as is done primarily       oral cancer, and herpes was found to induce
                                                          in Southeast Asia, and, more recently, using           dysplasia (abnormal cellular changes) in the lips
                                                          marijuana.                                             of hamsters when combined with the application
Heightening the risk                                                                                             of tobacco tar condensate.
                                                          The role of alcohol in oral carcinogenesis has
Oral cancer develops as a clone from a single             been demonstrated experimentally and appears           More recently, human herpes virus 8, a newly
genetically altered cell. It generally has a long         to be related to its damaging effect on the            identified member of the herpes virus family, has
latency period and invariably develops from a             liver. Major metabolites of alcohol, such as           been found in Kaposi’s sarcoma, an otherwise
precancerous lesion on the oral mucosa, such as a         acetaldehyde – a known carcinogen in animals           rare cancer occurring in patients with AIDS.
white leukoplakia, or more commonly, a reddish            – may also be important. Alcohol is also thought       These tumors often appear initially within the
erythroplakia. Both kinds of lesions are usually          to act as a solvent that facilitates the penetration   oral cavity. Other uncommon oral malignant
induced by tobacco use alone or in combination            of tobacco carcinogens into oral tissues.              tumors, such as Hodgkin’s lymphoma and
with heavy use of alcohol. The development                That observation may partly explain why the            non-Hodgkin’s lymphoma, can also occur in the
of squamous cell carcinoma from initial                   combined use of tobacco and alcohol produces           mouths of AIDS patients.
erythroplakia lesions has been well demonstrated          a greater risk for oral cancer than use of either
experimentally. Reported rates of malignant                                                                      In addition to viruses, infection with strains of
                                                          substance alone. Indeed, tobacco and alcohol,          the fungus Candida albicans has been linked to
transformation for leukoplakias are between 0.13          working in tandem, are thought to account for 75
and 17.5 percent. However, there is considerable                                                                 the development of oral cancers via the fungal
                                                          to 90 percent of all oral and pharyngeal cancers       production of nitrosamines, which are known
debate as to the actual malignant potential of            in the United States.
the leukoplakia lesion associated with the use of                                                                carcinogens.
smokeless (spit) tobacco. Meaningful data for             viruses                                                genetic derangements
determining a specific malignant transformation           The role of viruses in causing cancer in animals       Of the more than 50 known oncogenes, many
rate or relative risk of oral cancer due to               was established early in the century when              have been reported to be present in oral cancer,
smokeless tobacco use are difficult to obtain             Rous showed that a virus, later named the              and multiple oncogenes have been reported in
because of the confounding effects of other               Rous sarcoma virus (RSV), caused tumors in             oral and pharyngeal cancer. Some of these are
habits such as concurrent smoking and alcohol             chickens. The issue of whether viruses could           Bcl-1, c-erb-B2, c-myc, ins-2 and members of the
consumption and because of the variations in              cause cancer in humans remained unexplored             ras family.
smokeless (spit) products and how they are used.          until the mid-1970s, when Varmus and Bishop
Another oral precancerous lesion that has                 showed that RSV had a special gene, which they         The genetic derangements that can give rise to
received attention is submucous fibrosis. It is           called src (for sarcoma), that could transform         oral cancer, including many mutations associated
commonly seen in India and Southeast Asia and             the cell it infected into a malignant cell. It was     with the transformation of proto-oncogenes, have
is related to betel nut use.                              an oncogene, or cancer-causing gene. The               received notable attention. In some instances,
                                                          researchers subsequently, and surprisingly,            a change in a single nucleotide base – a point
Early epidemiologic studies identified behaviors                                                                 mutation – in a gene encoding a proto-oncogene
                                                          discovered that src was not native to the virus,
such as smoking and environmental factors                                                                        is enough to transform it into an oncogene.
                                                          but had been picked up by some ancestor virus
such as exposure to solar radiation and x-rays as                                                                Cancerous changes may also involve alterations,
                                                          from a chicken cell’s own genome, where src had
causes of intraoral and lip cancers. Researchers                                                                 deletions and break points in chromosomes that
                                                          presumably played a role in the chicken cell’s
then sought experimentally to explain the                                                                        affect the position of genes.
                                                          normal growth and development. Somehow RSV
mechanisms of initiation. In the 1980s and
                                                          was able to subvert src when it infected a chicken     Mutations that disarm the cell’s DNA repair
1990s, investigators exploited the techniques of
                                                          cell to cause the cell to divide uncontrollably.       mechanisms as well as mutations in tumor
molecular biology and genetics to probe what
was going on deep inside the cell. These studies          Varmus and Bishop called the normal cellular           suppressor genes, which inhibit abnormal cell
revealed an abundance of systemic and local               src gene a proto-oncogene, meaning that it had         growth, play a major role in cancer development.
factors, including viral and fungal infections, that      the potential to be converted to an oncogene.          If an individual inherits or acquires a mutation
affect cell behavior. Some factors stimulate cell         Subsequent research led to the discovery of            in one or more tumor-suppressor genes, for
division and others inhibit it – even to the point        other viruses that could cause tumors in animals       example, the loss of this protective mechanism
of initiating a program of cell “suicide,” called         and revealed the presence of proto-oncogenes           reduces the number of other deleterious changes
apoptosis. How a given cell behaves at any given          in birds and mammals. These genes could also           needed for cancer to develop.
time in its life cycle is the net result of the signals   be converted to oncogenes, behaving exactly            Tumor suppressor genes suspected to be mutated
it receives from neighboring cells and molecules,         like those carried by cancer viruses. In 1982, an      in oral and pharyngeal cancers include those for
from circulating factors in the blood or immune           oncogene isolated from a human bladder cancer          Rb, p16 (MTS1, CDKN2, or IN4a), and p53. Of
system and from its own internal controls. The            turned out to be virtually identical to ras, the       the group of tumor suppressor genes, that coding
following sections provide a brief description            oncogene found in a rat sarcoma virus.                 for p53 is considered of major importance, with
of these factors and how they may participate in          Viruses that have been implicated in oral cancer       mutations in the p53 gene detected in many
enhancing the risk for the development of oral            include herpes simplex type 1 and human                types of cancer, including oral and pharyngeal.
cancers.                                                  papillomavirus. Epstein-Barr virus, also a herpes      The p53 gene has been called the “guardian of
Page 50                                                                                                                                                   Elite CME
the genome” because of its ability to recognize                removed, and they usually do not grow
damage to a cell’s DNA and stop the process                    back.                                          Lipoma                  A tumor made up of
of growth and division until the damage is                  Š Cells from benign tumors do not invade                                  mature fat cells.
repaired. If repair is not possible, p53 can trigger           the tissues around them.
apoptosis. Mutations in the p53 gene in oral                Š Cells from benign tumors do not spread          Neurofibroma            A fibrous tumor
cancer have been linked to smoking and alcohol                 to other parts of the body.                                            consisting of nerve
use.                                                       Malignant tumors:                                                         tissue.
                                                            Š Malignant tumors are cancer.
Loss of immunosurveillance and control                      Š Malignant tumors are generally more             Odontogenic             Tumors in the jaw.
The immune system can, as first noted by Paul                                                                 tumors
                                                               serious than benign tumors.
Ehrlich in 1909, seek and destroy initial clones
                                                            Š They may be life-threatening.
of transformed cancer cells. Ehrlich called this                                                              Osteochondroma          A tumor made up of
                                                            Š Sometimes they grow back.
process immunosurveillance, and it has been                                                                                           bone and cartilage.
                                                            Š Cells from malignant tumors can invade
confirmed in experimental animals and in humans
                                                               and damage nearby tissues and organs.
with induced immunosuppression.                                                                               Papilloma               A tumor that
                                                            Š Cells from malignant tumors can spread
                                                                                                                                      resembles a wart,
One mechanism of immunosurveillance                            to other parts of the body.
                                                                                                                                      growing on the
involves stimulating cytotoxic macrophages and                  The cells spread by breaking away
                                                                                                                                      epithelium (the cells
lymphocytes to migrate to the tumor site and                       from the original cancer (primary
                                                                                                                                      that form the skin and
release tumor necrosis factors alpha and beta.                     tumor) and entering the bloodstream                                mucous membranes).
Another mechanism operative in oral cancer                         or lymphatic system.
appears to be stimulation of Langerhans cells,                  They invade other organs, forming            Pyogenic                A small, round bump
a special group of immune cells, in the oral                       new tumors and damaging these              granuloma               that often has an
mucosa. Other immune cells implicated in tumor                     organs.                                                            ulcerated surface.
rejection are natural killer cells and lymphokine-              The spread of cancer is called
activated killer cells.
                                                                   metastasis.                                Rhabdomyoma             A striated-muscle
There is an increased incidence of cancer in                                                                                          tumor that may
patients with AIDS or other immunodeficient
                                                       What are benign tumors?                                                        appear on the tongue,
                                                       There are many forms of benign (noncancerous)
conditions or with induced immunosuppression                                                                                          pharynx, uterus,
                                                       tumors that can appear in the oral cavity or
prior to organ transplantation.                                                                                                       vagina or heart.
                                                       oropharynx (in addition to other sites in/on the
In addition, there is evidence that smoking            body), including:                                      Schwannoma              A single tumor
depresses the immune system, and this may be
                                                                                                                                      that grows in
one of the ways in which smoking acts as a major                          Benign tumors                                               the neurilemma
risk factor in oral cancer.
                                                                                                                                      (Schwann’s sheath)
growth factors                                             Condyloma             A small, moist, pink                                 of nerves.
Immune cells are potent generators of growth               acuminatum            or red growth that
factors and other molecules that can stimulate             (also known as a      grows alone or in            Verruca form            Wart-shaped tumors.
other cells to migrate and proliferate. This               genital warts)        cauliflower-like             xanthoma
capacity is important in normal cell growth                                      clusters.
and turnover, in wound healing and in coping                                                                Some benign tumors disappear on their own.
with infection. Unfortunately, the release of              Eosinophilic          A benign tumor             Others may have to be removed surgically. Most
growth factors can contribute to oral cancer by            granuloma             that most often            benign tumors do not recur. Patients should
stimulating keratinocyte (oral epithelial cell)                                  affects children and       consult their physician for a diagnosis.
proliferation. Increased levels of transforming                                  adolescents and is
                                                                                 usually found in a
                                                                                                            What oral conditions may be
growth factor alpha (TGF-alpha) and epidermal                                                               precancerous?
growth factor have been found in oral and                                        bone or the lungs.
                                                                                                            Two conditions in the mouth – leukoplakia and
pharyngeal cancers and therefore could serve as                                                             erythroplakia – actually can be precursors to
markers for malignancy. Nicotine at high doses             Fibroma               A benign tumor
                                                                                 consisting of fibrous      cancer. Often caused by smoking or chewing
stimulates the release of growth hormones,                                                                  tobacco, these (initially) benign conditions can
among other endocrine effects.                                                   connective tissues.
                                                                                                            occur anywhere in the mouth. Only a biopsy can
understanding cancer                                       Keratoacanthoma       A flesh-colored,           determine whether precancerous cells (dysplasia)
Cancer begins in cells, the building blocks that                                 fast-growing bump          or cancer cells are present in a leukoplakia or
make up tissues. Tissues make up the organs of                                   on the skin with a         erythroplakia.
the body. Normally, cells grow and divide to form                                keratin plug in the         Leukoplakia – a condition characterized
new cells as the body needs them. When cells                                     center (keratin, the           by a whitish patch that develops inside the
grow old, they die, and new cells take their place.                              main component of              mouth or throat.
Sometimes this orderly process goes wrong.                                       the external layer of       Erythroplakia – a condition characterized
New cells form when the body does not need                                       skin, hair and nails, is       by a red, raised patch that develops inside the
them, and old cells do not die when they should.                                 a tough substance).            mouth.
These extra cells can form a mass of tissue called                                                          Treatment for leukoplakias or erythroplakias may
a growth or tumor. Tumors can be benign or                 Leiomyoma             A tumor of the             include use of retinoids – medications related to
malignant:                                                                       smooth muscle,             vitamin A – to eliminate, reduce, and/or prevent
 Benign tumors:                                                                 often found in the         dysplasia from forming.
    Benign tumors are not cancer:                                                esophagus, small
    Š Benign tumors are rarely life-threatening.                                 intestine, uterus or       What are malignant oral tumors?
    Š Generally, benign tumors can be                                            stomach.                   Although there are several types of malignant
                                                                                                            oral cancers, more than 90 percent of all
Elite CME                                                                                                                                               Page 51
diagnosed oral cancers are squamous cell             Cancer cells can also spread to other parts of            to quit smoking and about groups that offer
carcinoma.                                           the neck, the lungs and other parts of the body.          help to smokers who want to quit. Groups
                                                     When this happens, the new tumor has the same             offer counseling in person or by telephone.
               Malignant tumors                      kind of abnormal cells as the primary tumor. For         Help patients find a local smoking cessation
                                                     example, if oral cancer spreads to the lungs, the         program.
  Squamous           Also known as squamous          cancer cells in the lungs are actually oral cancer       Tell them about the medicines (bupropion,
  cell               cell cancer, this type of       cells. The disease is metastatic oral cancer, not         Chantix) or about nicotine replacement
  carcinoma          cancer originates in the        lung cancer. It is treated as oral cancer, not lung       therapy, which comes as a patch, gum,
                     squamous cell layer in the      cancer. Doctors sometimes call the new tumor              lozenges, nasal spray or inhaler.
                     lining of the oral cavity       “distant” or metastatic disease.                         Give them The “National Cancer Institute
                     and oropharynx. In the                                                                    Information Resources” information about
                     early stages, this cancer is    oral cancer: Who’s at risk?                               the federal government’s smoking cessation
                     present only in the lining      Dentists and doctors cannot always explain why
                                                                                                               website, http://www.smokefree.gov.
                     layer of cells (called          one person develops oral cancer and another does
                     carcinoma in situ). When        not. However, we do know that this disease is not     As a dental professional, you should discuss any
                     the cancer spreads beyond       contagious. Scientists have determined that one       concerns your patients share with you regarding
                     the lining, it is called        cannot “catch” oral cancer from another person.       cancer or any that you may have with them as
                     invasive squamous cell          Research has shown that people with certain risk      soon as possible. Discuss an appropriate schedule
                     cancer.                         factors are more likely than others to develop oral   for checkups. Alert your patients that not using
                                                     cancer. A risk factor is anything that increases      tobacco and limiting their use of alcohol are the
  Verrucous          Although also considered        your chance of developing a disease.                  most important things they can do to prevent
  carcinoma          a type of squamous cell                                                               oral cancers. If they spend a lot of time in the
                                                     The following are risk factors for oral cancer:
                     carcinoma, this low-grade                                                             sun, using a lip balm that contains sunscreen and
                                                      Tobacco: Tobacco use accounts for most oral
                     cancer rarely metastasizes                                                            wearing a hat with a brim will help protect their
                                                        cancers. Smoking cigarettes, cigars or pipes;
                     (spreads to distant sites).                                                           lips.
                                                        using chewing tobacco; and dipping snuff
                     Comprising less than 5                                                                Regular checkups can detect the early stages of
                                                        are all linked to oral cancer. The use of other
                     percent of all diagnosed                                                              oral cancer or conditions that may lead to oral
                                                        tobacco products (such as bidis and kreteks)
                     oral cancers, verrucous                                                               cancer. Check the tissues in the mouth as part of
                                                        may also increase the risk of oral cancer.
                     carcinoma can spread                                                                  the routine examination.
                                                        Heavy smokers who use tobacco for a long
                     deeply into surrounding
                                                        time are most at risk. The risk is even higher
                     tissue, requiring surgical                                                            symptoms
                                                        for tobacco users who drink alcohol heavily.
                     removal with a wide                                                                   Common symptoms of oral cancer include:
                                                        In fact, three out of four oral cancers occur
                     margin of surrounding                                                                  Patches inside the mouth or on the lips that
                                                        in people who use alcohol, tobacco, or both
                     tissue.                                                                                  are white, a mixture of red and white, or red.
                                                        alcohol and tobacco.
                                                                                                              White patches (leukoplakia) are the most
                                                      Alcohol: People who drink alcohol are more
  Minor              The lining of the oral                                                                   common. White patches sometimes become
                                                        likely to develop oral cancer than people
  salivary           cavity and oropharynx                                                                    malignant. Mixed red and white patches
                                                        who don’t drink. The risk increases with the
  gland cancers      contains numerous                                                                        (erythroleukoplakia) are more likely than
                                                        amount of alcohol that a person consumes.
                     salivary glands.                                                                         white patches to become malignant. Red
                                                        The risk increases even more if the person
                     Sometimes cancer will                                                                    patches (erythroplakia) are brightly colored,
                                                        both drinks alcohol and uses tobacco.
                     originate in a salivary                                                                  smooth areas that often become malignant.
                                                      Sun: Cancer of the lip can be caused by
                     gland. Treatment depends                                                               A sore on the lip or in the mouth that won’t
                                                        exposure to the sun. Using a lotion or lip
                     on the type and location of                                                              heal.
                                                        balm that has a sunscreen can reduce the risk.
                     the salivary gland cancer,                                                             Bleeding in the mouth.
                                                        Wearing a hat with a brim can also block the
                     as well as the extent of                                                               Loose teeth.
                                                        sun’s harmful rays. The risk of cancer of the
                     spreading. According                                                                   Difficulty or pain when swallowing.
                                                        lip increases if the person also smokes.
                     to the American Cancer                                                                 Difficulty wearing dentures.
                                                      A personal history of head and neck
                     Society, salivary gland                                                                A lump in the neck.
                                                        cancer: People who have had head and neck
                     cancers account for less                                                               An earache.
                                                        cancer are at increased risk of developing
                     than 1 percent of all                                                                 Most often, these symptoms do not mean cancer.
                                                        another primary head and neck cancer.
                     cancers.                                                                              An infection or another problem can cause the
                                                        Smoking increases this risk. Some studies
                                                        suggest that not eating enough fruits and          same symptoms.
oral cancer and squamous cells
                                                        vegetables may increase the chance of getting
Oral cancer is part of a group of cancers called                                                           Diagnosis
                                                        oral cancer. Scientists also are studying
head and neck cancers. Oral cancer can develop                                                                If your patient comes to you with symptoms
                                                        whether infections with certain viruses (such
in any part of the oral cavity or oropharynx. Most                                                             that suggest oral cancer, such as red or white
                                                        as the human papillomavirus) are linked to
oral cancers begin in the tongue and in the floor                                                              patches, lumps, swelling or other problems,
                                                        oral cancer.
of the mouth.                                                                                                  you should explain to him or her very
                                                     Quitting tobacco reduces the risk of oral cancer.         carefully that you are doing a special exam.
Almost all oral cancers begin in the flat cells
                                                     Also, quitting reduces the chance that a person          Discuss this with the patient and explain
(squamous cells) that cover the surfaces of the
                                                     with oral cancer will get a second cancer in the          that the exam includes looking carefully at
mouth, tongue, and lips. These cancers are called
                                                     head and neck region. People who stop smoking             the roof of the mouth, back of the throat and
squamous cell carcinomas. When oral cancer
                                                     can also reduce their risk of cancer of the lung,         insides of the cheeks and lips.
spreads (metastasizes), it usually travels through
                                                     larynx, mouth, pancreas, bladder and esophagus.          Let the patient know that you will gently pull
the lymphatic system. Cancer cells that enter the
                                                     There are many resources to help smokers quit:            out the tongue so it can be checked on the
lymphatic system are carried along by lymph, a
                                                      Advise patients to call The Cancer                      sides and underneath. Tell them that you will
clear, watery fluid. The cancer cells often appear
                                                         Information Service at 1-800-4-CANCER                 check the floor of the mouth and lymph nodes
first in nearby lymph nodes in the neck.
                                                         where they can talk with callers about ways           in the neck.

Page 52                                                                                                                                            Elite CME
   Explain each step carefully. This is not a         A biopsy is the only sure way to know whether           Chest x-rays: Images of the chest and lungs
    routine exam for you, and it is definitely not a   the abnormal area is cancerous. When discussing          can show whether cancer has spread to these
    routine checkup for your patient.                  a biopsy with patients, it is always good to be          areas.
   When the exam is complete, you will need to        prepared to answer these questions:                     CT scan: An x-ray machine linked to a
    discuss the next step with the patient.             Why do I need a biopsy?                                computer takes a series of detailed pictures of
                                                        How much tissue do you expect to remove?               the body.
Early diagnosis of oral and pharyngeal                  How long will it take? Will I be awake? Will           Š Depending on the type of tests, an
cancers                                                    it hurt?                                                 injection of dye may be used.
Dentists and primary care providers can counsel         How soon will I know the results?                      Š Tumors in the mouth, throat, neck or
patients about lifestyle behaviors that increase the    Are there any risks? What are the chances of               elsewhere in the body show up on the CT
risk for oral cancers. Dental as well as medical           infection or bleeding after the biopsy?                  scan.
personnel have provided successful tobacco              How should I care for the biopsy site                 MRI: A powerful magnet linked to a
control programs in their offices. Generally,              afterward? How long will it take to heal?            computer is used to make detailed pictures.
Americans are ill-informed about the risk factors       Will I be able to eat and drink normally after         The dentist or doctor can view these pictures
as well as the signs and symptoms of oral cancers          the biopsy?                                          on a monitor and can print them on film.
The mass media have paid little attention to the        If I do have cancer, who will talk with me             An MRI can show whether oral cancer has
topic, and health education textbooks are nearly           about treatment? When?                               spread.
devoid of discussion. The scant attention that has
been paid to oral cancers has focused on the role      If an exam shows an abnormal area, a small           Treatment
of spit tobacco.                                       sample of tissue may be removed. Usually, a          Many people with oral cancer want to take
                                                       biopsy is done with local anesthesia. Sometimes,     an active part in making decisions about
At present, the principal test for oral and            it is done under general anesthesia. A pathologist   their medical care. Be prepared to discuss all
pharyngeal cancers is a comprehensive clinical         then looks at the tissue under a microscope to       options with the patient. However, shock and
examination that includes a visual/tactile             check for cancer cells.                              stress after the diagnosis can make it hard to
examination of the mouth, full protrusion of
                                                       Remember, your patients are scared, because          think of everything they want to ask. It often
the tongue with the aid of a gauze wipe and
                                                       cancer is very serious. They will not understand     helps to make a list of questions and answers,
palpation of the tongue, floor of the mouth and
                                                       many things. They will need you to explain           have this ready to give to the patient before
lymph nodes in the neck. The U.S. Preventive
                                                       everything to them and their family. It is often     an appointment. Specialists who treat oral
Services Task Force concluded that there was
                                                       a good idea to schedule a family appointment         cancer include oral and maxillofacial surgeons,
insufficient evidence to recommend for or against
                                                       to discuss the type of cancer and the necessary      otolaryngologists (ear, nose and throat doctors),
routine screening for oral cancers, but noted that
                                                       treatment.                                           medical oncologists, radiation oncologists and
clinicians should remain vigilant for signs and
                                                                                                            plastic surgeons. There may be a team that
symptoms of oral cancers and premalignancy             staging cancer                                       includes specialists in surgery, radiation therapy
in people who use tobacco or regularly use             Staging is the key to finding the cancer in the      or chemotherapy. Other health care professionals
alcohol. The Canadian Task Force on Periodic           early development. When found early, oral            who may work with the specialists as a team
Health Examination states that although there          cancers have an 80 to 90 percent survival rate.      include a speech pathologist, nutritionist and
is insufficient evidence to include or exclude         Unfortunately at this time, the majority are found   mental health counselor.
screening for oral cancers from the periodic           as late-stage cancers, and this accounts for the
health examination for the general public, those       very high death rate of about 45 percent at five     surgical treatment for oral and
at high risk (smokers and heavy drinkers) over         years from diagnosis, and high treatment-related     pharyngeal cancers
60 warrant an annual oral cancer exam by a             morbidity in survivors. Late-stage diagnosis is    Surgical treatment for oral and pharyngeal
physician or dentist. The American Cancer              not occurring because these cancers are hard       cancers can result in functional impairment as
Society recommends annual examinations for             to discover, it is because of a lack of public     well as permanent disfigurement. Problems
individuals 40 and older and for individuals who       awareness coupled with the lack of a national      may include the loss of part of the tongue, loss
are exposed to known risks. Nevertheless, a 1992       program for opportunistic screenings which         of taste, loss of chewing ability, difficulty in
national survey showed that only 15 percent            would yield early discovery by medical and         speaking and pain. Furthermore, in addition to
of U.S. adults reported ever having had an oral        dental professionals. Worldwide the problem is     concerns about their function and their future,
cancer examination.                                    far greater, with new cases annually exceeding     oral and pharyngeal cancer patients must cope
There are large gaps in knowledge of the efficacy      481,000.                                           with an altered appearance. In a study of patients
of oral cancer examinations and the effectiveness                                                         who were disease-free from six months to eight
                                                       If the biopsy shows that cancer is present, you    years following surgical tumor removal, those
and cost-effectiveness of community approaches         will need to know the stage (extent) of the
to early detection of oral cancers. Methodologies                                                         with more pronounced disfigurement had greater
                                                       disease to plan the best treatment. The stage is   changes in self-image, a worsened relationship
and settings differ across studies. Moreover,          based on the size of the tumor, whether the cancer with their partner, reduced sexuality and
these studies do not provide definitive evidence       has spread and, if so, to what parts of the body.
supporting the oral cancer exam, and there have                                                           increased social isolation. One study noted that
                                                       Staging may require lab tests. It also may involve 30 percent of oral and pharyngeal cancer patients
been no controlled clinical trials for defining the    endoscopy. This involves a thin, lighted tube
effectiveness of screening programs. Further                                                              were still experiencing psychological distress
                                                       (endoscope) to check the throat, windpipe and      seven to 11 years after treatment. Depression,
research is thus needed.                               lungs. You will need to explain this procedure     too, is frequent in cancer patients. Patients with
Biopsy                                                 to the patient before scheduling the appointment   oral and pharyngeal cancers are at an even greater
If the exam shows an abnormal area, a small            and inform them that local anesthesia is used to   risk for depression than other cancer patients, due
sample of tissue may be removed. Removing              ease the discomfort. This exam may be done in a to surgeries that alter their appearance. Because
tissue to look for cancer cells is called a biopsy.    dental office, an outpatient clinic or a hospital. oral and pharyngeal cancers are also frequently
Usually, a biopsy is done with local anesthesia.       At this time the dental professional may order     associated with chronic alcohol and tobacco
Sometimes, it is done under general anesthesia.        one or more imaging tests to learn whether the     use, depression may be related to withdrawal
A pathologist then looks at the tissue under a         cancer has spread:                                 from these substances or to pre-existing
microscope to check for cancer cells.                   Dental x-rays: An x-ray of the entire mouth      psychopathology. Persistent pain, as noted earlier,
                                                            can show whether cancer has spread to the     may also be a contributing factor to depression.
Elite CME                                                                                                                                              Page 53
A study conducted a prospective analysis of           may be required to give an acceptable cosmetic            External radiation: The radiation comes
changes in quality of life over time with the aim     and functional result. Bone grafts and surgical            from a machine. Patients go to the hospital or
of identifying which factors might be predictive      flaps such as the radial forearm flap are used             clinic once or twice a day, generally five days
of future improvements or declines. Participants      to help rebuild the structures removed during              a week for several weeks.
were 186 oral and pharyngeal cancer patients,         excision of the cancer. An oral prothesis may also        Internal radiation (implant radiation): The
all smokers or recent former smokers, diagnosed       be required.                                               radiation comes from radioactive material
with primary carcinomas of the oral cavity,                                                                      placed in seeds, needles, or thin plastic tubes
                                                      Survival rates for oral cancer depend on the
pharynx, or larynx.                                                                                              put directly in the tissue. The patient stays
                                                      precise site, and the stage of the cancer at
                                                                                                                 in the hospital. The implants remain in place
The patients were tested at baseline, at one month    diagnosis. Overall, survival is around 50 percent
                                                                                                                 for several days. Usually they are removed
after radiation and/or surgery, and one year later    at five years when all stages of initial diagnosis
                                                                                                                 before the patient goes home. Some people
(for a subset of 105 patients available for follow-   are considered. Survival rates for stage 1 cancers
                                                                                                                 with oral cancer have both kinds of radiation
up). Measures used included the Karnofsky             are 90 percent, hence the emphasis on early
Performance Scale, which uses expert judgments        detection to increase survival outcome for
of functional performance scored from 0 to 100;       patients.                                              Chemotherapy
the Cancer Rehabilitation Evaluation System                                                                  Chemotherapy uses anticancer drugs to kill
                                                      Following treatment, rehabilitation may be
Short Form, in which patients rate their quality of                                                          cancer cells. It is called systemic therapy because
                                                      necessary to improve movement, chewing,
life along physical, psychosocial, marital, sexual                                                           it enters the bloodstream and can affect cancer
                                                      swallowing and speech. Speech and language
and medical interaction scales; the previously                                                               cells throughout the body.
                                                      pathologists may be involved at this stage.
mentioned Performance Status Scale for Head
                                                      Chemotherapy is useful in oral cancers when            Chemotherapy is usually given by injection. It
and Neck Cancer Patients (which includes scales
                                                      used in combination with other treatment               may be given in an outpatient part of the hospital,
for eating and speaking); and the Profile of Mood
                                                      modalities such as radiation therapy. It is seldom     at the dentist/doctor’s office, or at home. Rarely, a
States, in which patients rate their feelings over
                                                      used alone as a monotherapy. When cure is              hospital stay may be needed.
the previous week, yielding analyses that enable
scaling along six mood states: tension-anxiety,       unlikely, it can also be used to extend life and       Rehabilitation after oral cancer
depression-dejection, anger-hostility, confusion-     can be considered palliative but not curative          Rehabilitation may vary from person to person
bewilderment, and vigor-activity.                     care. Biological agents such as Cetuximab              depending on the type of oral cancer treatment
                                                      have recently been shown to be effective in the        and the location and extent of the cancer.
Results indicated that in spite of functional
                                                      treatment of squamous cell head and neck cancers       Rehabilitation may include:
improvement on some scales over time, there
                                                      and are likely to have an increasing role in the        Dietary counseling: Many patients
was continued dysfunction in speech and eating.
                                                      future management of this condition when used              recovering from oral cancer surgery have
Patients also reported declines in marital and
                                                      in conjunction with other treatments.                      difficulty eating, so it is often recommended
sexual functioning, as well as an increase in
alcohol use. Interestingly, the best predictor of     Treatment of oral cancer will usually be by                that they eat small meals consisting of soft,
quality of life one year after treatment was the      a multidisciplinary team, with treatment                   moist foods.
scores obtained after initial smoking cessation       professionals from the realms of radiation,             Surgery: Some patients may benefit from
advice was given, while the patients were             surgery, chemotherapy, nutrition, dental                   reconstructive or plastic surgery to restore
undergoing treatment and in recovery. Other           professionals, and even psychology all possibly            the bones or tissues of the mouth, returning a
predictors were treatment type (quality of life was   involved with diagnosis, treatment, rehabilitation,        more normal appearance.
generally poorer for radiation patients) and score    and patient care.                                       Prosthesis: If reconstructive or plastic
on the vigor subscale of the Profile of Mood                                                                     surgery is not an option, patients may benefit
                                                      Complications may include:                                 from dental or facial-part prosthesis to restore
States. The investigators concluded that medical       Postoperative disfigurement of the face, head
follow-up must integrate tailored psychological                                                                  a more normal appearance. Special training
                                                         and neck.                                               may be needed to learn to use a prosthetic
and behavioral interventions to achieve better         Complications of radiation therapy, including
quality of life for oral and pharyngeal cancer                                                                   device.
                                                         dry mouth and difficulty swallowing.                 Speech therapy: If a patient experiences
patients.                                              Other metastasis (spread) of the cancer.                 difficulty in speaking following oral cancer
Type of procedure                                     Methods of treatment                                       treatment, speech therapy may help the
Surgical excision (removal) of the tumor is           Oral cancer treatment may include surgery,                 patient relearn the process.
usually recommended if the tumor is small             radiation therapy, or chemotherapy. Some
enough, and if surgery is likely to result in a                                                              side effects of cancer treatment
                                                      patients have a combination of treatments. At          The possible side effects should be explained to
functionally satisfactory result. Radiation therapy   any stage of disease, people with oral cancer
is often used in conjunction with surgery or as                                                              each patient before treatment begins. Because
                                                      may have treatment to control pain and other           treatment often damages healthy cells and tissues,
the definitive radical treatment, especially if the   symptoms, to relieve the side effects of therapy,
tumor is inoperable. Surgeries for oral cancers                                                              unwanted side effects are common. These side
                                                      and to ease emotional and practical problems.          effects depend mainly on the location of the
include:                                              This kind of treatment is called supportive care,
 Maxillectomy (can be done with or without                                                                  tumor and the type and extent of the treatment.
                                                      symptom management or palliative care.                 Side effects may not be the same for each person,
     orbital exenteration).
 Mandibulectomy (removal of the mandible or          Radiation therapy                                      and they may even change from one treatment
     lower jaw or part of it).                        Radiation therapy (also called radiotherapy) is a      session to the next.
 Glossectomy (tongue removal, can be total,          type of local therapy. It affects cells only in the    Conclusion
     hemi or partial).                                treated area. Radiation therapy is used alone for      While the diagnosis of oral cancer remains a
 Radical neck dissection.                            small tumors or for patients who cannot have           challenge, oral health has come a long way in
 Moh’s procedure.                                    surgery. It may be used before surgery to kill         the last several years. Dental professionals,
 Combinational, e.g., glossectomy and                cancer cells and shrink the tumor. It also may
                                                                                                             researchers and clinicians can provide the latest
     laryngectomy, done together.                     be used after surgery to destroy cancer cells that
                                                                                                             information in cancer prevention and continue
                                                      may remain in the area. Radiation therapy uses
Owing to the vital nature of the structures in the                                                           to promote access to cancer screening services
                                                      high-energy rays to kill cancer cells. Doctors use
head and neck area, surgery for larger cancers is                                                            and clinical trials through a number of outreach
                                                      two types of radiation therapy to treat oral cancer:
technically demanding. Reconstructive surgery                                                                initiatives.
Page 54                                                                                                                                                Elite CME
Definitions                                                 water. It may be applied to the teeth as a gel,        vessels (a network of thin tubes that carry
   Benign – Not cancerous. Benign tumors do                in toothpaste, or as a rinse.                          lymph and white blood cells).
    not spread to tissues around them or to other          General anesthesia – Drugs that cause loss            Malignant – Cancerous. Malignant tumors
    parts of the body.                                      of feeling or awareness and put the person to          can invade and destroy nearby tissue and
   Bidi – A cigarette made by rolling tobacco by           sleep.                                                 spread to other parts of the body.
    hand into a dried leaf. Most bidis come from           Gland – An organ that makes one or more               Medical oncologist – A doctor who
    India in a variety of flavors.                          substances, such as hormones, digestive                specializes in diagnosing and treating cancer
   Biopsy – The removal of cells or tissues for            juices, sweat, tears, saliva or milk. Endocrine        using chemotherapy, hormonal therapy and
    examination under a microscope. When only               glands release the substances directly into            biological therapy. A medical oncologist
    a sample of tissue is removed, the procedure            the bloodstream. Exocrine glands release               often is the main health care provider for a
    is called an incisional biopsy or core biopsy.          the substances into a duct or opening to the           person who has cancer. A medical oncologist
    When an entire lump or suspicious area                  inside or outside of the body.                         also may coordinate treatment provided by
    is removed, the procedure is called an                 Graft – Healthy skin, bone or other tissue             other specialists.
    excisional biopsy. When a sample of tissue or           taken from one part of the body and used to           Mental health counselor – A specialist who
    fluid is removed with a needle, the procedure           replace diseased or injured tissue removed             can talk with patients and their families about
    is called a needle biopsy or fine-needle                from another part of the body.                         emotional and personal matters, and can help
    aspiration.                                            Hard palate – The front, bony portion of the           them make decisions.
   Bupropion – A substance that is used to treat           roof of the mouth.                                    Metastasis – The spread of cancer from
    depression and to help people quit smoking.            Head and neck cancer – Cancer that arises              one part of the body to another. A tumor
    It belongs to the family of drugs called                in the head or neck region (in the nasal cavity,       formed from cells that have spread is called
    antidepressants.                                        sinuses, lip, mouth, salivary glands, throat or        a “metastatic tumor” or a “metastasis.” The
   Cancer – A term for diseases in which                   larynx [voice box]).                                   metastatic tumor contains cells that are like
    abnormal cells divide without control.                 Human papillomaviruses – HPVs. Viruses                 those in the original (primary) tumor. The
    Cancer cells can invade nearby tissues and              that cause abnormal tissue growth (warts).             plural form of metastasis is metastases.
    can spread through the bloodstream and                  Some types of HPV are associated with                 MRI – Magnetic resonance imaging – A
    lymphatic system to other parts of the body.            cervical and certain other cancers.                    procedure in which radio waves and a
   Cell – The individual unit that makes up all           Imaging – Tests that produce pictures of               powerful magnet linked to a computer
    of the tissues of the body. All living things           areas inside the body.                                 are used to create detailed pictures of
    are made up of one or more cells.                      Implant radiation – A procedure in which               areas inside the body. These pictures can
   Chemotherapy – Treatment with anticancer                radioactive material sealed in needles, seeds,         show the difference between normal and
    drugs.                                                  wires or catheters is placed directly into or          diseased tissue. MRI makes better images
   Clinical trial – A type of research study               near a tumor. Also called brachytherapy,               of organs and soft tissue than other scanning
    that uses volunteers to test new methods of             internal radiation or interstitial radiation           techniques, such as CT or X-ray. MRI is
    screening, prevention, diagnosis or treatment           therapy.                                               especially useful for imaging the brain,
    of a disease. The study may be carried out in          Internal radiation – A procedure in which              spine, the soft tissue of joints, and the inside
    a clinic or other medical facility. Also called a       radioactive material sealed in needles, seeds,         of bones. Also called nuclear magnetic
    clinical study.                                         wires or catheters is placed directly into or          resonance imaging.
   CT scan – Computed tomography scan. A                   near a tumor. Also called brachytherapy,              Nutritionist – A health professional with
    series of detailed pictures of areas inside             implant radiation or interstitial radiation            special training in nutrition who can offer
    the body taken from different angles; the               therapy.                                               help with the choice of foods a person eats
    pictures are created by a computer linked to           Kretek – A cigarette made of a mixture of              and drinks. Sometimes called a dietitian.
    an x-ray machine. Also called computerized              tobacco and clove spices.                             Oral cavity – The mouth.
    tomography and computerized axial                      Leukoplakia – A white patch that may                  Oral and maxillofacial surgeon – A dentist
    tomography (CAT) scan.                                  develop on mucous membranes such as the                who specializes in surgery of the mouth, face
   Dental implant – A small metal pin placed               gums, the tongue or the inside of the cheeks,          and jaw.
    inside the jawbone or oral tissue. Dental               and may become cancerous.                             Radiation therapy – The use of high-
    implants can be used to help anchor a false            Local anesthesia – Drugs that cause a                  energy radiation from x-rays, gamma rays,
    tooth or teeth, or a crown or bridge.                   temporary loss of feeling in one part of the           neutrons and other sources to kill cancer
   Dentist – A health professional who                     body. The patient remains awake but has no             cells and shrink tumors. Radiation may come
    specializes in caring for the teeth, gums and           feeling in the part of the body treated with the       from a machine outside the body (external-
    oral tissues.                                           anesthetic.                                            beam radiation therapy), or from materials
   Endoscope – A thin, lighted tube used to look          Local therapy – Treatment that affects cells           called radioisotopes. Radioisotopes produce
    at tissues inside the body.                             in the tumor and the area close to it.                 radiation and can be placed in or near the
   Endoscopy – The use of a thin, lighted tube            Lymph – The clear fluid that travels through           tumor or in the area near cancer cells.
    (called an endoscope) to examine the inside             the lymphatic system and carries cells that            This type of radiation treatment is called
    of the body.                                            help fight infections and other diseases. Also         internal radiation therapy, implant radiation,
   Erythroleukoplakia – A patch found in the               called lymphatic fluid.                                interstitial radiation, or brachytherapy.
    mouth that is a mixture of red and white. It           Lymph node – A rounded mass of lymphatic               Systemic radiation therapy uses a radioactive
    can develop into cancer.                                tissue that is surrounded by a capsule of              substance, such as a radiolabeled monoclonal
   Erythroplakia – A reddened patch with a                 connective tissue. Lymph nodes filter lymph            antibody, that circulates throughout the body.
    velvety surface found in the mouth. It can              (lymphatic fluid), and they store lymphocytes          Also called radiotherapy, irradiation, and
    develop into cancer.                                    (white blood cells). They are located along            x-ray therapy.
   External radiation – Radiation therapy that             lymphatic vessels. Also called a lymph gland.         Radioactive – Giving off radiation.
    uses a machine to aim high-energy rays at the          Lymphatic system – The tissues and organs             Radiotherapy – The use of high-energy
    cancer. Also called external-beam radiation.            that produce, store and carry white blood              radiation from x-rays, gamma rays, neutrons
   Fluoride – A mineral that helps prevent tooth           cells that fight infections and other diseases.        and other sources to kill cancer cells and
    decay. Fluoride may be present in drinking              This system includes the bone marrow,                  shrink tumors. Radiation may come from
                                                            spleen, thymus, lymph nodes and lymphatic              a machine outside the body (external-
Elite CME                                                                                                                                                  Page 55
     beam radiation therapy), or it may come                                                             NOTES
     from radioactive material placed in the                   oRAL HEALTH AnD oRAL
     body near cancer cells (internal radiation                 PHARyngEAL CAnCERs
     therapy, implant radiation or brachytherapy).             Final Examination Exercises
     Systemic radiation therapy uses a radioactive           Choose True or False for questions
     substance, such as a radiolabeled monoclonal        1 through 5 and mark your answers on the
     antibody, that circulates throughout the body.          Final Examination Sheet found on
     Also called radiation therapy, irradiation, and         page 109 or take your test online at
     x– ray therapy.                                            www.onlinedentalCE.com.
    Saliva – The watery fluid in the mouth made
     by the salivary glands. Saliva moistens food
     to aid in digestion and protects the mouth        1. The canines, or cuspids, are designed for
     against infections.                                  heavy grinding and chewing, exerting
    Side effects – Problems that occur when              forces as high as 200-plus pounds.
     treatment affects tissues or organs other                   True                False
     than the ones meant to be affected by the
     treatment. Some common side effects of
     cancer treatment are fatigue, pain, nausea,       2. The great majority of infectious diseases
     vomiting, decreased blood cell counts, hair           affect or are acquired through mucosal
     loss and mouth sores.                                 surfaces.
    Soft palate – The muscular (not bony) part at               True                False
     the back of the roof of the mouth.
    Speech pathologist – A specialist
                                                       3. Two conditions in the mouth – leukoplakia
     who evaluates and treats people with
                                                          and erythroplakia – actually can be
     communication and swallowing problems.
                                                          precursors to cancer.
     Also called a speech therapist.
    Squamous cell carcinoma – Cancer that                       True                False
     begins in squamous cells, which are thin,
     flat cells that look like fish scales. Squamous   4. If oral cancer spreads to the lungs, the
     cells are found in the tissue that forms the         cancer cells in the lungs are actually oral
     surface of the skin, the lining of the hollow        cancer cells. The disease is metastatic lung
     organs of the body and the passages of the           cancer.
     respiratory and digestive tracts. Also called
     epidermoid carcinoma.                                       True                False
    Squamous cells – Flat cells that look like fish
     scales under a microscope. These cells cover      5. Staging is the key to finding the cancer in
     internal and external surfaces of the body.          the early development.
     They are found in the tissue that forms the
                                                                 True                False
     surface of the skin, the lining of the hollow
     organs of the body and the passages of the
     respiratory and digestive tracts.
    Stage – The extent of a cancer within the
     body. If the cancer has spread, the stage
     describes how far it has spread from the
     original site to other parts of the body.
    Staging – Performing exams and tests to
     learn the extent of the cancer within the body,
     especially whether the disease has spread
     from the original site to other parts of the
     body. It is important to know the stage of the
     disease in order to plan the best treatment.
    Tumor – A new mass of excess tissue that
     results from abnormal cell division. Tumors
     perform no useful body function. They may
     be benign (not cancerous) or malignant
    Uvula – The soft flap of tissue that hangs
     down at the back of the mouth (at the edge of
     the soft palate).
    X-ray – A type of high-energy radiation.
     In low doses, x-rays are used to diagnose
     diseases by making pictures of the inside of
     the body. In high doses, x-rays are used to
     treat cancer.
sAmerican Cancer Society
sAmerican Surgeon General
Page 56                                                                                                          Elite CME
                    CHAPTER 5                           attacks and strokes. But a lot can be done to             blood glucose during the day of and the days
oRAL CoMPLiCATions WiTH DisEAsEs                        prevent or slow down diabetes problems.                   following the dental procedure.
                  (3 CE HouRs)                                                                                Diabetes can cause serious problems in
Learning objectives                                                                                           the mouth.
!   Identify oral complications with diabetes.                                                                If you have a patient with
!   List ways to prevent complications with                                                                   diabetes, discuss this with
    diabetes.                                                                                                 the person and make sure he
!   Apply your understanding of cancer                                                                        or she stays on a routine
    treatment and oral health.                                                                                schedule with your office.
!   Prepare your patients for oral care after                                                                 People with diabetes are at risk for mouth
    hematopoietic stem cell transplantation.                                                                  infections, especially periodontal disease, which
!   Assess patients before and after radiation and                                                            can lead to painful chewing problems.
    chemotherapy.                                       guide your patients to a healthier
!   Discuss the role of cancer pretreatment oral        lifestyle and give them these suggestions.            Other problems diabetes can cause are dry mouth
    care.                                                  Work with a dietitian to design a healthy         and a fungal infection called thrush. Dry mouth
!   Review the complications of the heart with              eating plan.                                      happens when a person does not have enough
    infective endocarditis.                                Create an exercise program that works with        saliva. Diabetes may also cause the glucose level
!   Describe the oral problems caused by                    daily activities. Discuss this with a medical     in saliva to increase. Together, these problems
    Sjögren’s syndrome.                                     doctor. Being active at least 30 minutes every    may lead to thrush, which causes painful white
!   Explain the treatment that can be done for              day will make a big difference.                   patches in the mouth.
    xerostomia/salivary gland dysfunction.                 Always take medication as directed.
                                                                                                              Impress upon your diabetic patients that by
                                                           Check blood glucose every day or as directed
introduction                                                                                                  controlling their blood glucose, brushing and
                                                            by a medical doctor.
To achieve and maintain good oral health, people                                                              flossing every day and visiting a dentist regularly,
                                                           Keep a record of blood glucose; write it in a
with diseases often require a special approach to                                                             they can prevent periodontal disease
                                                            book or on a notepad.
dental care. With the help of their dentist, patients      Check feet every day for cuts, blisters, sores,   Cancer treatment and oral health
who practice good daily dental care can prevent             swelling, redness or sore toenails.               Most people are aware of common side effects
bleeding, pain and even the spread of germs or             Brush and floss teeth daily.                      of cancer treatment like nausea and hair loss. But
bacteria to other parts of their bodies. Few people        Control blood pressure and cholesterol.           many don’t realize that more than one-third of
even realize that side effects of many diseases            Don’t smoke.                                      people treated for cancer develop complications
affect the mouth. But these complications may                                                                 that affect the mouth. These problems may
require special care and create needs that interfere    How can diabetes hurt the teeth and                   interfere with cancer treatment and diminish the
with a patient’s quality of life. This course is        gums?                                                 patient’s quality of life.
designed to help dental professionals better            High blood glucose helps bacteria grow in the
understand some of these special needs so they          mouth, which can cause the patient to develop         oral complications of cancer treatment
can include some of the strategies in their general     red, sore and swollen gums that bleed when they       With more than 1.4 million new cases of cancer
practice setting and help their patients cope with      brush their teeth.                                    diagnosed each year and a shift to outpatient
these diseases.                                                                                               management, you will likely see some of
                                                        People with diabetes can have tooth and gum           these patients in your practice. Because cancer
Diabetes and oral health                                problems more often if their blood glucose stays      treatment can affect the oral tissues, you need
How does diabetes affect the mouth?                     high, and it can make tooth and gum problems          to know about potential oral side effects.
People who have diabetes know the disease can           worse or cause tooth loss.                            Preexisting or untreated oral disease can also
harm the eyes, nerves, kidneys, heart and other         Smoking makes it more likely for the patient to       complicate cancer treatment. Your role in patient
important systems in the body. But it also can          get a bad case of gum disease, especially for a       management can extend benefits beyond the oral
cause problems in the mouth.                            person with diabetes or one who is age 45 or          cavity.
People with diabetes are at special risk for            older. Red, sore and bleeding gums are the first      Oral complications from radiation to the head and
periodontal disease, which can lead to painful          sign of gum disease.                                  neck or chemotherapy for any malignancy can
chewing difficulties and tooth loss for the patient.    Some diabetes medicine can cause low blood            compromise patients’ health and quality of life,
Dry mouth, often a symptom of undetected                glucose, called hypoglycemia. A dentist might         and affect their ability to complete planned cancer
diabetes, can cause soreness, ulcers, infections        want to talk with a patient’s medical doctor          treatment. For some patients, the complications
and tooth decay. Smoking makes these problems           before the person’s visit about the best way to       can be so debilitating that they may tolerate
worse.                                                  take care of his or her blood glucose during the      only lower doses of therapy, postpone scheduled
What can be done for this problem?                      dental work. The patient may need to bring some       treatments or discontinue treatment entirely. Oral
Good blood glucose control is key to controlling        diabetes medicine and food to your office to help     complications can also lead to serious systemic
and preventing mouth problems. People with              maintain a level blood glucose.                       infections. Medically necessary oral care before,
poor blood glucose control get gum disease                                                                    during and after cancer treatment can prevent
                                                        If the mouth is sore after the dental work, the
more often and more severely than people whose                                                                or reduce the incidence and severity of oral
                                                        patient may not be able to eat or chew for several
diabetes is well controlled. Daily brushing and                                                               complications, enhancing both patient survival
                                                        hours or days. For guidance on how to adjust
flossing, regular dental check-ups and good blood                                                             and quality of life.
                                                        their normal routine while their mouth is healing,
glucose control are the best defense against the        check with the medical doctor or dietitian and        oral complications related to cancer
oral complications of diabetes.                         plan the following:                                   treatment
What are diabetes problems?                              What foods and drinks the patient should            Oral complications of cancer treatment arise in
Too much glucose in the blood for a long time                have.                                            various forms and degrees of severity, depending
can cause diabetes problems. This high blood             Whether the patient should change diabetes          on the individual and the cancer treatment.
glucose can damage many parts of the body, such              medicine routines.                               Chemotherapy often impairs the function of
as the heart, blood vessels, eyes and kidneys.           How often the patient should check his or her       bone marrow, suppressing the formation of
Heart and blood vessel disease can lead to heart                                                              white blood cells, red blood cells and platelets
Elite CME                                                                                                                                                 Page 57
(myelosuppression). Some cancer treatments                 to exercise three times a day, opening and             Platelets           150,000 – 400,000/mm3
are described as stomatotoxic because they                 closing the mouth as far as possible without
have toxic effects on the oral tissues. Both               pain; repeat 20 times.                                 White blood cells   4,500 – 10,000 cells/mcL
chemotherapy and radiation therapy come with              Consult with the oncology team about use of
specific complications. You will need to consider          dentures and other appliances after muscositis         Differential white blood cell (WBC) count
the possibility of these complications each time           subsides. Patients with friable tissues and
                                                                                                                  Neutrophils     40 – 60           (3000 – 6000/
you evaluate a patient with cancer.                        xerostomia may not be able to wear them
                                                                                                                  (PMNs)          percent           mm3)
Head and neck radiation, chemotherapy, and                                                                        Neutrophils     0 – 3 percent     (0 – 300/
                                                          Watch for demineralization and caries.
blood and marrow transplantation can cause oral                                                                   (Bands)                           mm3)
                                                           Lifelong, daily applications of fluoride gel are
complications ranging from dry mouth to life-
                                                           needed for patients with xerostomia.                   Eosinophils     1 – 4 percent     (50 – 400/
threatening infections.
                                                          Advise against elective oral surgery                                                     mm3)
Head and neck radiation therapy                            on irradiated bone because of the risk                 Basophils       0.5 – 1           (15 – 15/
Patients receiving radiation therapy to the                of osteonecrosis. Tooth extraction, if                                 percent           mm3)
head and neck are at risk for developing                   unavoidable, should be conservative, using
oral complications. Because of the risk of                 antibiotic coverage and possibly hyperbaric            Lymphocytes     20 – 40           (1200 – 3000/
osteonecrosis in irradiated fields, oral surgery           oxygen therapy.                                                        percent           mm3)
should be performed before radiation treatment                                                                    Monocytes       2 – 8 percent     (100 – 600/
begins.                                                                                                                                             mm3)
                                                     The oral complications of chemotherapy depend
Before head and neck radiation therapy               upon the drugs used, the dosage, the degree                  Absolute neutrophil count = WBC x ( percent
 Conduct a pretreatment oral health                 of dental disease and the use of radiation.                  PMNs + percent bands)
   examination and prophylaxis.                      Chemoradiation therapy carries a significant risk            Source: A.D.A.M. Medical Encyclopedia
 Schedule dental treatment in consultation          for mucositis.                                               (Internet) http://www.nimnih.gov/medlineplus/
   with the radiation oncologist.                                                                                 ency/article/003643.htm
                                                     Before chemotherapy
 Extract teeth in the proposed radiation field                                                               After chemotherapy
                                                      Conduct a pretreatment oral health
   that may be a problem in the future.                                                                        Place the patient on a dental recall schedule
                                                        examination and prophylaxis.
 Prevent tooth demineralization and radiation                                                                   when chemotherapy is completed and all side
                                                      Schedule dental treatment in consultation
   caries:                                                                                                       effects, including immunosuppression, have
                                                        with the oncologist.
   Š Fabricate custom gel-applicator trays for                                                                   resolved.
                                                      Schedule oral surgery at least seven to 10
       the patient.                                                                                            Confirm normal hematologic status prior to
                                                        days before myelosuppresive therapy begins.
   Š Prescribe a 1.1 percent neutral pH sodium                                                                   dental treatment.
                                                      Consult the oncologist before conducting any
       fluoride gel or a 0.4 percent stannous,                                                                 Ask whether the patient has received
                                                        oral procedures in patients with hematologic
       unflavored fluoride gel (not fluoride                                                                     intravenous bisphosphonate therapy.
                                                        cancers; do not conduct procedures in
                                                        patients who are immunosuppressed or have             oral complications common to both
   Š Use a neutral fluoride for patients with
       porcelain crowns or resin or glass                                                                     chemotherapy and radiation
       ionomer restorations.                         During chemotherapy                                           Oral mucositis: Inflammation and ulceration
   Š Be sure that the trays cover all tooth           Consult the oncologist before any dental                     of the mucous membranes; can increase the
       structures without irritating the gingival       procedure, including prophylaxis.                           risk for pain, oral and systemic infection,
       or mucosal tissues.                            Ask the oncologist to order blood work 24                    and nutritional compromise. Culture lesions
   Š Instruct the patient in home application of        hours before oral surgery or other invasive                 to identify secondary infection. Prescribe
       fluoride gel. Several days before radiation      procedures. Postpone when:                                  topical anesthetics and system analgesics.
       therapy begins, the patient should start a       Š The platelet count is less than 75,000/                   Consult the oncologist about prescribing
       daily 10-minute application.                         mm3 or abnormal clotting factors are                    antimicrobial agents for known infections.
   Š Have patients brush with a fluoride gel if             present.                                                Have the patient avoid rough-textured foods
       using trays is difficult.                        Š Absolute neutrophil count is less than                    and report oral problems early.
 Allow at least 14 days of healing for any oral            1,000/mm3 or consider prophylactic                     Infection: Viral, bacterial and fungal; results
   surgical procedures.                                     antibiotics. (American Heart Association)               from myelosuppression, xerostomia and/or
 Conduct prosthetic surgery before treatment,        Check for oral source of viral, bacterial or                 damage to the mucosa from chemotherapy or
   because elective surgical procedures are             fungal infection in patients with fever of                  radiotherapy.
   contraindicated on irradiated bone.                  unknown origin.                                            Xerostomia/salivary gland dysfunction:
                                                      Encourage consistent oral hygiene measures.                  Dryness of the mouth due to thickened,
During radiation therapy
                                                      Consult the oncologist about the need for                    reduced or absent salivary flow; increases the
 Monitor the patient’s oral hygiene.
                                                        antibiotic prophylaxis before any dental                    risk of infection and compromises speaking,
 Watch for muscositis and infection.
                                                        procedures in patients with central venous                  chewing and swallowing. Medications other
 Advise against wearing removable appliances
                                                        catheters.                                                  than chemotherapy can also cause salivary
   during treatment.
                                                                                                                    gland dysfunction. Persistent dry mouth
After radiation therapy                                  Normal complete blood count                                increases the risk for dental caries. Advise
 Recall the patient for prophylaxis and home-           Red blood cells     Male: 4.7 – 6.1 million                the patient to soften or thin foods with
   care evaluation every four to eight weeks or                              cells/mcL                              liquid, chew sugarless gum, or suck ice chips
   as needed for the first six months after cancer                           Female: 4.2 – 5.4 million              or sugar-free hard candies. Suggest using
   treatment.                                                                cells/mcL                              commercial saliva substitutes or prescribe a
 Reinforce the importance of optimal oral                                                                          saliva stimulant.
                                                         Hemoglobin          Male 13.8 – 17.2 gm/dL
   hygiene.                                                                                                        Functional disabilities: Impaired ability
                                                                             Female: 12.1 – 15.1 gm/dL
 Monitor the patient for trismus; check for                                                                        to eat, taste, swallow and speak because of
   pain or weakness in masticating muscles               Hematocrit          Males 40.7 – 50.3 percent              mucositis, dry mouth, trismus and infection.
   in the radiation field. Instruct the patient                              Female: 36.1 – 44.3
Page 58                                                                                                                                                  Elite CME
   Taste alterations: Changes in taste                   and neck radiation for oral, pharyngeal and          problem to prevent later extraction-induced
    perception of foods, ranging from unpleasant          laryngeal cancer.                                    osteonecrosis.
    to tasteless. Refer to a dietitian.               Some complications occur only during treatment;         Conduct a prosthodontic evaluation if
   Nutritional compromise: Poor nutrition            others, such as xerostomia, may persist for years.       indicated. If a removable prosthesis is worn,
    from eating difficulties caused by mucositis,     Unfortunately, patients with cancer often do not         make sure that it is clean and well adapted to
    dry mouth, dysphagia and loss of taste.           receive oral care until serious complications            the tissue. Instruct the patient not to wear the
   Abnormal dental development: Altered              develop.                                                 prosthesis during treatment, if possible; or at
    tooth development, craniofacial growth, or                                                                 the least, not to wear it at night.
    skeletal development in children secondary        The role of pretreatment oral care                      Perform oral prophylaxis if indicated.
    to radiotherapy and/or high doses of              A thorough oral evaluation by a knowledgeable           Time oral surgery to allow at least two weeks
    chemotherapy before age 9.                        dentist before cancer treatment begins is                for healing before radiation therapy begins.
   Etched enamel: Advise the patient to rinse        important to the success of the regimen.                 For patients receiving radiation treatment,
    the mouth with water and baking soda              Pretreatment oral care achieves the following:           this is the best time to consider surgical
    solution after vomiting to protect enamel.         Reduces the risk and severity of oral                  procedures. Oral surgery should be performed
                                                          complications.                                       at least seven to 10 days before the patient
other complications of chemotherapy
                                                       Allows for prompt identification and                   receives myelosuppressive chemotherapy.
Neurotoxicity: Persistent, deep aching and
                                                          treatment of existing infections or other            Medical consultation is indicated before
burning pain that mimics a toothache, but for
                                                          problems.                                            invasive procedures.
which no dental or mucosal source can be found.
                                                       Improves the likelihood that the patient              Remove orthodontic bands and brackets if
This complication is a side effect of certain
                                                          will successfully complete planned cancer            highly stomatotoxic chemotherapy is planned
classes of drugs, such as the vinca alkaloids.
                                                          treatment.                                           or if the appliances will be in the radiation
Provide analgesics or systemic pain relief.
                                                       Prevents, eliminates or reduces oral pain.             field.
Bleeding: Oral bleeding from the decreased             Minimizes oral infections that could lead to          Consider extracting highly mobile primary
platelets and clotting factors associated with            potentially serious systemic infections.             teeth in children, and teeth that are expected
the effects of therapy on bone marrow. Advise          Prevents or minimizes complications that               to exfoliate during treatment.
the patient to clean teeth thoroughly with a              compromise nutrition.                               Prescribe an individualized oral hygiene
toothbrush softened in warm water; to avoid            Prevents or reduces later incidence of bone            regimen to minimize oral complications.
flossing the areas that are bleeding but to keep          necrosis.                                            Patients undergoing head and neck radiation
flossing the other teeth.                              Preserves or improves oral health.                     therapy should be instructed on the use of
other complications of radiation therapy               Provides an opportunity for patient education          supplemental fluoride.
Demineralization and radiation caries: Prescribe          about oral hygiene during cancer therapy.
                                                                                                           Supplemental fluoride
daily fluoride gel applications before treatment       Improves the quality of life.
                                                                                                           Fluoride rinses are not adequate to prevent tooth
starts. Continue for the patient’s lifetime if         Decreases the cost of care.
                                                                                                           demineralization. Instead, a high-potency fluoride
changes in quality or quantity of saliva persist.     With a pretreatment oral evaluation, the dental      gel, delivered via custom gel-applicator trays,
Radiation caries: Lifelong risk of rampant            team can identify and treat problems such as         is recommended. Several days before radiation
dental decay that may begin within three months       infection, fractured teeth or restorations, or       therapy begins, patients should start a daily
of completing radiation treatment if changes in       periodontal disease that could contribute to oral    10-minute application of a 1.1 percent neutral
either the quality or quantity of saliva persist.     complications when cancer therapy begins. The        pH sodium fluoride gel or a 0.4 percent stannous
                                                      evaluation also establishes baseline data for        fluoride (unflavored) gel. Patients with porcelain
Trimus/tissue fibrosis: Loss of elasticity of         comparing the patient’s status in subsequent         crowns or resin or glass ionomer restorations
masticatory muscles that restrict normal ability to   examinations.                                        should use a neutral pH fluoride. Be sure that the
open the mouth. Instruct the patient on stretching
                                                      Before the exam, you will need to obtain             trays cover all tooth structures
exercises for the jaw to prevent or reduce the
                                                      the patient’s cancer diagnosis and treatment         without irritating the gingival
severity of fibrosis.
                                                      plan, medical history and dental history. Open       or mucosal tissues.
Osteonecrosis: Blood vessel compromise and            communication with the patient’s oncologist is       For patients reluctant to use a
necrosis of bone exposed to high-dose radiation       essential to ensure that each provider has the       tray, a high-potency fluoride
therapy; results in decreased ability to heal if      information necessary to deliver the best possible   gel should be brushed on the teeth following
traumatized. Avoid invasive procedures involving      care.                                                daily brushing and flossing. Either 1.1 percent
irradiated bone, particularly the mandible.
                                                      Patient evaluation                                   neutral pH sodium or 0.4 percent stannous
Who has oral complications?                           Ideally, a comprehensive oral evaluation should      fluoride gel is recommended, based on the
Oral complications occur in virtually all             take place one month before cancer treatment         patient’s type of dental restorations.
patients receiving radiation for head and neck        starts to allow adequate time for recovery from      Questions to ask the medical oncologist
malignancies, in approximately 80 percent             any required invasive dental procedures. The         1. What is the patient’s complete blood count,
of hematopoietic (blood-forming) stem cell            pretreatment evaluation includes a thorough             including absolute neutrophil and platelet
transplant recipients, and in nearly 40 percent of    examination of hard and soft tissues as well            counts?
patients receiving chemotherapy. Risk for oral        as appropriate radiographs to detect possible        2. If an invasive dental procedure needs to be
complications can be classified as low or high:       sources of infection and pathology. Also take the       done, are there adequate clotting factors?
 Lower risk: Patients receiving minimally            following steps before cancer treatment begins:      3. Does the patient have a central venous
    myelosuppressive or nonmyelosuppressive            Identify and treat existing infections, carious       catheter?
    chemotherapy.                                          and other compromised teeth, and tissue         4. What is the scheduled sequence of treatments
 Higher risk: Patients receiving stomatotoxic             injury or trauma.                                  so that safe dental treatment can be planned?
    chemotherapy resulting in prolonged                Stabilize or eliminate potential sites of          5. Is radiation therapy also planned?
    myelosuppression, including patients                   infection.
    undergoing hematopoietic stem cell                                                                     Questions to ask the radiation oncologist
                                                       Extract teeth in the radiation field that are
    transplantation; and patients undergoing head                                                          1. What parts of the mandible/maxilla and
                                                           nonrestorable or may pose a future
                                                                                                              salivary glands are in the field of radiation?
                                                                                                           2. What is the total dose of radiation the patient

Elite CME                                                                                                                                              Page 59
   will receive, and what will be the impact on            Exercise the jaw muscles three times a day to     called the endocardium. The condition also is
   these areas?                                             prevent and treat jaw stiffness from radiation    called infective endocarditis (IE)
3. Has the vascularity of the mandible been                 treatment.
                                                                                                              Infective endocarditis occurs if bacteria, fungi,
   previously compromised by surgery?                      Avoid candy, gum and soda unless they are
                                                                                                              or other germs invade the bloodstream and attach
4. How quickly does the patient need to start               sugar-free.
                                                                                                              to abnormal areas of the heart. The infection
   radiation treatment?                                    Avoid spicy or acidic foods, toothpicks,
                                                                                                              can damage the heart and cause serious and
5. Will there be induction chemotherapy with                tobacco products and alcohol.
                                                                                                              sometimes fatal complications. It can develop
   the radiation treatment?
                                                        special care for children                             quickly or slowly; it depends on what type of
Hematopoietic stem cell transplantation         Children receiving chemotherapy and/or                        germ is causing it and whether the patient has
Most stem cell transplant patients develop acuteradiation therapy are at risk for the same oral               an underlying heart problem. When it develops
oral complications, especially patients with graft-
                                                complications as adults. Other actions to consider            quickly, it is called acute infective endocarditis.
versus-host disease.                            in managing pediatric patients include:                       When it develops slowly, it is called subacute
                                                 Before the cancer treatment begins, extract                 infective endocarditis.
Before transplantation
 Conduct a pretreatment oral health                loose primary teeth and teeth expected to                 The disease mainly affects people who have:
   examination and prophylaxis.                     exfoliate during cancer treatment.                         Damaged or artificial (man-made) heart
 Consult the oncologist about scheduling           Š Remove orthodontic bands and brackets                      valves.
   dental treatment.                                    if highly stomatotoxic chemotherapy is                 Congenital heart defects (defects present at
 Schedule oral surgery at least seven to 10            planned or if the appliances will be in the              birth).
   days before myelosuppressive therapy begins.         radiation field.                                       Implanted medical devices in the heart or
 Prevent tooth demineralization and radiation   Monitor craniofacial and dental structures                     blood vessels.
   caries:                                          for abnormal growth and development.
                                                                                                              People who have normal heart valves also can
    Š     Instruct the patient in home application of   oral complications and the heart with                 have this disease. However, the condition is much
          fluoride gel (not fluoride rinses).           infective endocarditis                                more common in people who have abnormal
    Š     Explain the necessary oral hygiene            Endocarditis is a sometimes life-threatening          hearts.
          regimen to the patient.                       infection of the inner surface of the heart and/
                                                        or its valves. Of the approximately 15,000            Certain factors make it easier for bacteria to enter
After transplantation
                                                        cases of endocarditis reported each year in the       the bloodstream. These factors put the patient
 Consult the oncologist before any dental
                                                        United States, many likely arise when bacteria        at higher risk for infective endocarditis. For
   procedure, including prophylaxis.
                                                        that naturally attach to our teeth are displaced      example, poor dental hygiene and unhealthy teeth
 Monitor the patient’s oral health for plaque
                                                        and pass into the bloodstream during a dental         and gums increase the risk for the infection.
   control, tooth demineralization, dental caries
   and infection.                                       procedure, flossing, or even chewing food.            Other risk factors include using intravenous (IV)
 Watch for infections on the tongue and                These microbes, while relatively harmless in the      drugs, having a catheter (tube) or another medical
   oral mucosa. Herpes simplex and Candida              mouth, have an affinity for damaged endothelial       device in the body for long periods, and having a
   albicans are common oral infections.                 cells or blood clots in the heart, where they         history of infective endocarditis.
 Delay elective oral procedures for one year.          attach, multiply and form larger bacterial colonies   Common symptoms of infective endocarditis are
 Follow patients for long-term oral                    that trigger the endocarditis. Scientists have        fever and other flu-like symptoms. Because the
   complications. Such problems are strong              shown that immune cells called monocytes are          infection can affect people in different ways, the
   indicators of chronic graft-versus-host              prominently found in early inflammatory lesions       signs and symptoms vary. The disease may cause
   disease.                                             linked to endocarditis. What’s been puzzling is       problems in many other parts of the body besides
 Monitor transplant patients carefully for             the monocytes tend to disappear from the lesions      the heart.
   second malignancies in the oral region.              over time without becoming macrophages, a
                                                        scavenging immune cell formed from monocytes          What causes endocarditis?
Advice for your patients
                                                        that removes debris from tissues, such as             The disease occurs if bacteria, fungi or other
 Brush teeth, gums and tongue gently with an
                                                        the damaged, bacteria-laden cells linked to           germs invade the bloodstream and attach
   extra-soft toothbrush and fluoride toothpaste
                                                        endocarditis.                                         to abnormal areas of the heart. A common
   after every meal and at bedtime. If brushing
                                                                                                              underlying factor in infective endocarditis is a
   hurts, soften the bristles in warm water.            In a report in the journal Infection and Immunity,    structural heart defect, especially faulty heart
 Floss teeth gently every day. If gums bleed           NIDCR grantees show that the usual monocyte-          valves. Usually the immune system will kill
   and hurt, avoid the areas that are bleeding or       macrophage transformation rarely occurs               germs in the bloodstream. If the heart has a rough
   sore but keep flossing your other teeth.             because monocytes infected in studies with            lining or abnormal valves, the invading germs
 Follow instructions for fluoride gel                  the well-known oral bacterium Streptococcus           can attach and multiply in the heart.
   applications.                                        mutans instead become dendritic cells, a type
 Avoid mouthwashes containing alcohol.                 of immune cell that initiates an inflammation-        Other factors also can play a role in causing the
 Rinse the mouth several times a day with a            producing immune response upon interaction            disease. Common activities, such as brushing the
   baking soda and salt solution, followed by           with this bacterium. This finding indicates that      teeth or having certain dental procedures, can
   a plain water rinse. Use ¼ teaspoon each             oral streptococci-mediated changes in a person’s      allow bacteria to enter the bloodstream. This is
   of baking soda and salt in 1 quart of warm           normal immune response can contribute to              even more likely to happen if the teeth and gums
   water. Omit salt during mucositis.                   endocarditis. It also suggests that an effective      are in poor condition.
 Try the following if dry mouth is a problem:          future strategy to treat endocarditis might involve   Having a catheter, tube or other
   Š Sip water frequently.                              learning to turn off the destructive immune           medical device inserted through
   Š Suck ice chips or use sugar-free gum or            response and/or reprogram the monocytes to            the skin, especially for long periods,
       candy.                                           produce macrophages to clear away the disease-        can allow bacteria to enter the
   Š Use saliva substitute spray or gel or a            causing bacterial colonies from the heart.            bloodstream. People who use
       prescribed saliva stimulant if appropriate.                                                            intravenous (IV) drugs also are at risk for
   Š Avoid glycerin swabs.                              Endocarditis is an infection of the inner lining of
                                                        the heart chambers and valves. This lining is         infective endocarditis because of the germs on
                                                                                                              needles and syringes.

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Bacteria may spread to the blood and heart from                  Small, painful, red purplish bumps         rarely in patients with Sjögren’s syndrome. Pain
infections in other parts of the body such as the                 under the skin on the fingers or toes.     and stiffness in the joints with mild swelling may
gut, skin or genitals.                                         Tiny spots under the fingernails, on         occur in some patients, even in those without
                                                                  the whites of the eyes, on the roof of     rheumatoid arthritis or lupus. Rashes on the
Endocarditis complications                                                                                   arms and legs related to inflammation in small
   This disease can cause many complications;                    the mouth and inside of the cheeks,
                                                                  or on the chest. These spots are from      blood vessels (vasculitis) and inflammation in the
    the most common is problems with the
                                                                  broken blood vessels.                      lungs, liver, and kidney may occur rarely and be
    heart. They occur in one-third to one-half
                                                          Š   Nausea, vomiting, a decrease in appetite,      difficult to diagnose. Neurological complications
    of all people who have the infection. These
                                                              a sense of fullness with discomfort on the     that cause symptoms such as numbness, tingling
    problems may include:
                                                              upper left side of the abdomen or weight       and weakness have also been described in some
    Š A heart murmur.
                                                              loss with or without a change in appetite.     patients.
    Š Heart failure.
    Š Heart valve damage.                                 Š   Blood in the urine.                            What causes sjögren’s syndrome?
    Š Heart block.                                        Š   Swelling in the feet, legs or abdomen.         The cause of Sjögren’s syndrome is not known,
    Š Heart attack.                                                                                          but it is considered an autoimmune disorder.
   Complications of the central nervous system                                                              People with this disease have abnormal proteins
    occur in as many as 20 to 40 percent of                                                                  in their blood suggesting that their immune
    people who have infective endocarditis. The                                                              system, which normally functions to protect the
    central nervous system complications most                                                                body against cancers and invading infections, is
    often occur when bits of the vegetation called                                                           reacting against their own tissue. The decreased
    emboli break away and lodge in the brain.                                                                production of tears and saliva seen in Sjögren’s
    The emboli can cause local infections called                                                             syndrome occurs when the glands that produce
    brain abscesses. They also can cause a more       sjögren’s syndrome                                     these fluids are damaged by inflammation.
    widespread brain infection called meningitis.     In the early 20th century, Swedish physician           Research suggests that genetic factors and
    Š Emboli can cause strokes or seizures.           Henrik Sjögren (SHOW-gren) first described             possibly viral infections (as yet unidentified) may
         This happens if they block blood vessels     a group of women whose chronic arthritis was           predispose people to developing this condition.
         or affect the brain’s electrical signals.    accompanied by dry eyes and dry mouth. Today
         These complications can cause long-term      rheumatologists know more about the syndrome           Who gets sjögren’s syndrome?
                                                      that is named for Sjögren and, most significantly      Between 400,000 and 3.1 million adults have
         brain damage or even be fatal.
                                                      for patients, can provide advice about how to live     Sjögren’s syndrome. This condition can affect
   Infective endocarditis can affect other organs
                                                      with it.                                               people of any age, but symptoms usually appear
    in the body, such as the lungs, kidneys and
                                                       Sjögren’s syndrome sometimes develops                between the ages of 45 and 55. It affects 10 times
                                                          as a complication of another autoimmune            as many women as men. About half of affected
    Š The lungs are at risk when the
                                                          disorder.                                          patients also have rheumatoid arthritis or other
         endocarditis affects the right side of the
                                                       Symptoms vary in type and intensity, but             connective tissue diseases, such as lupus.
    Š The kidneys can become abscessed and                many people with Sjögren’s are able to live
                                                          normal lives.
                                                                                                             How is sjögren’s syndrome diagnosed?
         the infection can inflame the internal                                                              Diagnosis depends on a combination of
         filtering structures of the kidneys.          Although serious complications are rare,
                                                                                                             symptoms, physical findings, blood tests and
    Š The spleen can become enlarged,                     regular medical care is important.
                                                                                                             sometimes special studies. Dry eyes and mouth
         especially in people with long-term          What is sjögren’s syndrome?                            may be early signs of the condition but require
         infective endocarditis. Sometimes emboli     Sjögren’s syndrome is an inflammatory disease          further investigation because these symptoms
         can damage the spleen.                       that can affect many different parts of the body,      can be caused by many other conditions or
                                                      but most often affects the tear and saliva glands.     medications. Special tests may be used to assess
How can endocarditis be prevented?
                                                      Patients with this condition may notice irritation,    any decrease in tear or saliva production (an
To help your patients prevent endocarditis,
                                                      a gritty feeling or painful burning in the eyes. Dry   example would be the Schirmer test for tear
always take steps to maintain infection control in
                                                      mouth or difficulty eating dry foods and swelling      production). An eye examination is helpful in
your office and advise your patients to:
                                                      of the glands around the face and neck are also        detecting any eye changes seen in Sjögren’s.
 Let you know if they are at risk for
                                                      common. Some patients experience dryness of            Blood tests can determine the presence of
    endocarditis. (These patients may need an
                                                      other mucous membranes (such as the nasal              antibodies (immune system cells that help destroy
    antibiotic before routine dental exams and
                                                      passages, throat and vagina) and skin.                 foreign invaders) typical of the disease, including
    certain other dental and medical procedures.)
                                                                                                             anti-nuclear antibodies (ANA), anti-SSA and
 Brush and floss their teeth regularly.              “Primary” Sjögren’s syndrome occurs in
                                                                                                             SSB antibodies, or rheumatoid factor. Biopsies of
 Have regular dental checkups.                       people with no other rheumatologic disease.
                                                                                                             saliva glands around the face or under the surface
 Avoid body piercing, tattoos and other              “Secondary” Sjögren’s occurs in people who do
                                                                                                             of the inner lip may also sometimes be used to
    procedures that may allow germs to enter the      have another rheumatologic disease, most often
                                                                                                             establish a diagnosis.
    bloodstream.                                      lupus and rheumatoid arthritis.
 Be alert to the signs and symptoms of                                                                      How is sjögren’s syndrome treated?
                                                      Most of the complications of Sjögren’s syndrome
    infective endocarditis. (Advise the patient see                                                          Treatment is designed to lessen the most
                                                      occur because of decreased tears and saliva.
    a medical doctor if any of these symptoms                                                                bothersome symptoms. Dry eyes usually respond
                                                      Patients with dry eyes are at increased risk for
    persist.)                                                                                                to the use of artificial tears applied regularly
                                                      infections around the eye and may have damage
    Š Flu-like symptoms, such as fever chills,                                                               during the day or to gels applied at night. Other
                                                      to the cornea. Dry mouth may cause an increase
        fatigue (tiredness), aching muscles and                                                              measures, such as plugging or blocking tear
                                                      in dental decay, gingivitis (gum inflammation),
        joints, night sweat and headaches.                                                                   ducts, can be used in more severe cases. Eye
                                                      and oral yeast infections (thrush) that may cause
    Š Shortness of breath or a cough that won’t                                                              drops that reduce inflammation in the glands
                                                      pain and burning. Some patients have episodes of
        go away.                                                                                             around the eyes (cyclosporine-Restasis) may
                                                      painful swelling in the saliva glands around the
    Š A new heart murmur or a change in an                                                                   be used to increase tear production. Dry mouth
        existing heart murmur.                                                                               can be relieved by drinking water, chewing
    Š Skin changes such as :                          Complications in other parts of the body occur         gum or using saliva substitutes. Some patients
         Overall paleness.
Elite CME                                                                                                                                                Page 61
benefit from using prescription medications          Patients should see their physician regularly for       Apthous ulcers (canker sores): Red sores
that stimulate saliva flow, such as pilocarpine      general health screening and should pay close            that might also have a yellow-gray film on
(Salagen) or cevimuline (Evoxac). If patients        attention to any abnormal swelling in the glands         top. They are usually on the moveable parts
develop yeast infections, these can be relieved      around the face or neck, under the arms or in            of the mouth, such as the tongue or inside of
by anti-fungal therapies. The currently available    the groin areas because this may be a sign of            the cheeks and lips.
treatments may help relieve some of the dryness,     lymphoma.                                               Herpes: A viral infection, red sores usually
but usually some dryness persists.                   Sjögren’s syndrome is an autoimmune condition            on the roof of the mouth. They are sometimes
                                                     that can occur at any age, but is most common            on the outside of the lips, where they are
All patients should receive regular dental care in
                                                     in older women. Many patients develop                    called fever blisters.
order to prevent cavities and tooth loss that may
                                                     Sjögren’s syndrome as a complication of another         Hairy leukoplakia: This is caused by the
occur as a complication of the disorder. Patients
                                                     autoimmune disease, such as rheumatoid arthritis         Epstein-Barr virus. They are white patches
with dry eyes should see an ophthalmologist
                                                     or lupus.                                                that do not wipe away and are sometimes
regularly for signs of damage to the cornea.
                                                                                                              very thick and hairlike. They usually appear
Patients with excessive redness and pain in the      Most of the treatment for Sjögren’s syndrome             on the side of the tongue or sometimes on the
eyes should be evaluated for infections.             is aimed at relieving symptoms of dry eyes and           cheeks and lower lip.
Hydroxychloroquine (Plaquinel), an antimalarial      mouth and preventing and treating long-term             Candidiasis: This is a fungal yeast infection
drug used in lupus and rheumatoid arthritis,         complications such as infection and dental               that produces white or yellowish patches
may be helpful in some patients with Sjögren’s       disease. Currently available treatments often            (sometimes red). If wiped away, there will
syndrome by reducing joint pain and rash             do not completely eliminate the symptoms of              be redness or bleeding underneath. They can
experienced by some patients. Patients with          dryness in some patients.                                appear anywhere in the mouth.
rare but serious systemic symptoms, such             Most patients with Sjögren’s syndrome remain            Warts: Small, white, gray or pinkish rough
as fever, rashes, abdominal pain or lung or          healthy, but a number of rare complications have         bumps that look like cauliflower. They can
kidney problems, may require treatment with          been described, including an increased risk for          appear inside the lips and on other parts of
corticosteroids such as prednisone (Deltasone        cancer of the lymph glands (lymphoma). Thus,             the mouth.
and others) and/or immunosuppressive agents,         regular medical care and follow-up is important         Dry mouth xerostomia/salivary gland
such as methotrexate (Rheumatrex), azathioprine      for all patients.                                        dysfunction: This happens when the patient
(Imuran), mycophenolate (CellCept),                                                                           does not have enough saliva to keep the
cyclophosphamide (Cytoxan). In addition,             Mouth problems with human                                mouth wet. Without enough saliva, the
rituximab (Rituxan) and other biological             immunodeficiency virus (HIV)                             patient could develop tooth decay or other
therapies (as used in rheumatoid arthritis) are      Human immunodeficiency virus is a lentivirus             infections and might have trouble chewing
undergoing evaluation for treating patients with     (a member of the retrovirus family) that causes          and swallowing. This can cause the mouth to
severe systemic manifestations of disease.           acquired immunodeficiency syndrome (AIDS),               be very dry, with a burning feeling, cracked
                                                     a condition in humans in which the immune                and chapped lips. (See the section below on
Broader health impact of sjögren’s                   system begins to fail, leading to life-threatening       xerostomia).
syndrome                                             opportunistic infections. Infection with HIV
A vast majority of patients with Sjögren’s           occurs by the transfer of blood, semen, vaginal      Treatment for these include:
syndrome remain very healthy, without any            fluid, pre-ejaculate or breast milk. Within these     Infection control.
serious complications. Patients should be aware      bodily fluids, HIV is present as both free virus         Š Brush and floss regularly with a soft
that they do face an increased risk for infections   particles and virus within infected immune cells.            bristle toothbrush.
in and around the eyes and an increased risk for                                                           Apthous ulcers or canker sores: An over-
dental problems – both of which are due to the       HIV infection in humans is considered pandemic           the-counter cream or prescription mouthwash
long-term reduction in tears and saliva.             by the World Health Organization (WHO).                  that contains corticosteroids; for more severe
                                                     Nevertheless, complacency about HIV may play             cases, use corticosteroids pills.
Rarely, patients may have complications related      a key role in HIV risk. From its discovery in         Herpes: Antiviral medications can reduce the
to inflammation in other body systems, including:    1981 to 2006, AIDS killed more than 25 million           healing time and frequency of outbreaks.
 Joint and muscle pain with fatigue.                people. HIV infects about 0.6 percent of the          Hairy leukoplakia: Antivirals for the more
 Lung problems that may mimic pneumonia.            world’s population. In 2005 alone, AIDS claimed          severe cases may reduce symptoms. In some
 Abnormal liver and kidney function tests.          an estimated 2.4 million to 3.3 million lives, of        cases, a pain reliever may be required.
 Skin rashes related to inflammation of small       which more than 570,000 were children.                Candidiasis: A mild prescription for an
     blood vessels.
                                                     Oral problems are very common in people with             antifungal lozenge or mouthwash. An
 Neurologic problems causing weakness and
                                                     HIV. More than a third of people living with HIV         antifungal pill might be necessary for the
                                                     have oral conditions that arise because of their         more severe cases.
In a small number of people, Sjögren’s syndrome      weakened immune system. And even though               Warts in the mouth: These can be removed
may be associated with lymphoma, a cancer of         combination antiretroviral therapy has made              surgically or by cryosurgery. A prescription
the lymph glands.                                    some oral problems less common, others are               cream may be used for treatment. The warts
Living with sjögren’s syndrome                       occurring more often with this type of treatment.        may return after treatment.
People with Sjögren’s syndrome are usually able      These problems can be very painful, annoying         oral complications with xerostomia/
to live normal lives with very few adjustments.      and lead to other problems. Oral problems can
                                                                                                          salivary gland dysfunction or dry mouth
When a diagnosis is made, many patients must         also lead to trouble with eating, as well as cause
                                                                                                          Dry mouth is a complication of many of these
focus a great deal of attention dealing with dry     discomfort and embarrassment. If the mouth is
                                                                                                          diseases, but it is also a symptom of a gland
eyes and dry mouth, but these symptoms tend          in pain and has tenderness, it becomes difficult
to subside with time. Any pain or redness in         to chew and swallow, and the patient may
the eyes should be evaluated promptly, because       not eat enough, causing weight loss and other        Dry mouth is the feeling that there is not enough
this may signal an infection. To reduce risk for     complications. The body may not have enough          saliva in the mouth. Everyone has dry mouth
cavities and other dental problems, patients must    energy to deal with HIV.                             occasionally, often when they are nervous, upset,
pay close attention to proper oral hygiene and                                                            under stress or taking certain medications. Many
                                                     Some of the most common oral problems linked
regular dental care.                                                                                      older adults have dry mouth, but it is not a normal
                                                     with HIV can be treated; they include:
                                                                                                          part of aging.

Page 62                                                                                                                                            Elite CME
Saliva does more than keep the mouth wet. It            Tell patients to avoid tobacco or alcohol,          dental professional, you can help to prevent these
protects teeth from decay, it helps heal sores in        which will dry out the mouth.                       complications with a health care strategy and
the mouth and prevents infection by controlling         Suggest that the patient chew sugarless gum         advice on necessary home-care treatment, thus
bacteria, viruses and fungi in the mouth.                or suck on sugarless hard candy to stimulate        removing at least one problem for people facing
                                                         saliva flow.                                        such serious diseases.
Saliva helps digest food and helps us chew and
                                                        Tell the patient to stay away from spicy or
swallow. Saliva is involved in taste perception
                                                         salty foods because they will cause pain in a
as well. Each of these functions of saliva is
                                                         dry mouth.
hampered when a person has dry mouth. It can
                                                        Suggest using a humidifier at night to
                                                                                                                    oRAL CoMPLiCATions WiTH
be very uncomfortable. Some people notice a                                                                                DisEAsEs
                                                         promote moisture in the air while the patient
sticky, dry feeling in the mouth. Others notice a                                                                      Final Examination Exercises
                                                         is sleeping.
burning feeling or difficulty while eating. It may                                                                   Choose True or False for questions
cause the throat to feel dry, making swallowing      Scientists are exploring the potential use of               1 through 5 and mark your answers on the
difficult and choking common. People with dry        gene therapy – replacing, manipulating or                       Final Examination Sheet found on
mouth may get sores, cracked lips and a dry,         supplementing nonfunctional genes with healthy                  page 109 or take your test online at
rough tongue.                                        genes – to treat salivary gland dysfunction. The                   www.onlinedentalCE.com.
                                                     idea is to transfer additional or replacement genes
People get dry mouth when the glands in the
                                                     into the salivary glands of people with Sjögren’s
mouth that make saliva are not working properly
                                                     syndrome and cancer patients whose salivary              1. People with diabetes are not at risk for
and do not produce enough saliva to keep the
                                                     glands are damaged by radiation treatment.                  mouth infections such as thrush or dry
mouth healthy. There are several reasons why
                                                     The hope is that these genes will increase the              mouth.
salivary glands might not work right.
                                                     production of saliva and eliminate the chronic
More than 400 medicines, including some over-        parched sensation that bothers people with dry                     True                False
the-counter medications, can cause the salivary      mouth conditions.
glands to make less saliva, or to change the                                                                  2. After transplantation, you should monitor
                                                     Research efforts are also under way to develop an
composition of the saliva so that it can’t perform                                                               patients carefully for second malignancies
                                                     artificial salivary gland for patients who have lost
the functions it should. As an example, medicines                                                                in the oral region.
                                                     all salivary gland function. The first-generation
for urinary incontinence, allergies, high blood
                                                     artificial gland will be a tiny tube lined with cells              True                False
pressure and depression often cause dry mouth.
                                                     that have been engineered to produce saliva-like
Some diseases can affect the salivary glands. Dry    fluid. Made of biodegradable material, the tube          3. Infective endocarditis prevention includes
mouth can occur in patients with diabetes and        would be inserted into the inside of the cheek. All         avoiding body piercing or tattoos that can
Parkinson’s disease. Dry mouth is the hallmark       the components for the artificial gland have been           allow germs to enter the bloodstream.
symptom of the fairly common autoimmune              developed with the goal of producing a prototype
disease Sjögren’s syndrome.                          within a few years.                                                True                False
Sjögren’s syndrome can occur either by itself or     Advise patients to take these steps to prevent
with another autoimmune disease like rheumatoid                                                               4. Most people with Sjögren’s syndrome
                                                     xerostomia/salivary gland dysfunction or dry
arthritis or lupus. Salivary and tear glands are                                                                 suffer from lymphoma and have serious
the major targets of the syndrome, and the                                                                       complications.
                                                      Brush teeth several times a day with an
result is a decrease in production of saliva and         extra-soft toothbrush, at least after every meal               True                False
tears. The disorder can occur at any age, but the        and at bedtime. If brushing hurts, soften the
average person with the disorder at the Sjögren’s        bristles in warm water.                              5. Saliva protects teeth from decay, heals
Syndrome Clinic of the National Institute of          Floss teeth gently every day. If gums bleed,              sores in the mouth and prevents infection
Dental and Craniofacial Research (NIDCR) is              avoid the areas that are bleeding and sore.             by controlling bacteria, viruses and fungi in
in his or her late 50s. Women with the disorder       Always use toothpaste with fluoride.                      the mouth.
outnumber men 9 to 1.                                 Avoid sticky, sugary foods. Brush
                                                         immediately eating.                                            True                False
Certain cancer treatments can affect the salivary
glands. Head and neck radiation therapy can           Do not use mouthwashes with alcohol in
cause the glands to produce little or no saliva.         them. Alcohol can dry out the mouth.
Chemotherapy may cause the salivary glands to         If necessary, prescribe a fluoride gel to help
produce thicker saliva, which makes the mouth            prevent dental decay.
feel dry and sticky.                                 Conclusion
Injury to the head or neck can damage the nerves     There are many causes for oral complications,
that tell salivary glands to make saliva.            and the best way to help your patients is to stay
                                                     informed about the types of diseases, treatments
How is dry mouth treated?                            and ways to reduce the risk and impact of these
 First try to determine the cause.                  often painful side effects that diminish their
 Change the patient’s medication or dosage if       quality of life. Good oral health not only makes
  this is the cause.                                 them feel better, it also makes them look better
 Prescribe a medicine for the salivary glands,      and elevates their self-esteem, a very important
  if this is the cause.                              factor.
 Suggest the use of artificial saliva to keep the
  mouth wet.                                         But the most important fact to remember is that
 Suggest the patient drink lots of water and        good health begins in the mouth, and that saliva
  sugarless drinks.                                  carries germs through the bloodstream, which
 Instruct patients to avoid caffeine drinks such    can cause complications. Patients with these
  as coffee, tea and some sodas. (Caffeine can       diseases have been through so much that they
                                                     tend to ignore or “let go” their dental care. As a                                         DOH03OCE11
  dry out the mouth.)

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                    CHAPTER 6                          feelings and emotions through facial expressions.       was pursued as an important public health
      oRAL DisEAsEs, inFECTions                        They also provide protection against microbial          measure to prevent dental caries.
                                                       infections and environmental insults.
     AnD CRAnioFACiAL DisoRDERs                                                                                Although this measure has not been fully
                  (9 CE HouRs)                         The craniofacial tissues also provide a useful          implemented, the results have been dramatic.
Learning objectives                                    means to understanding organs and systems in            Dental caries began to decline in the 1950s
!   Explain new research and findings regarding        less accessible parts of the body. The salivary         among children who grew up in fluoridated
    the connection between oral health and             glands are a model of other exocrine glands, and        cities, and by the late 1970s, decline in decay
    overall health.                                    an analysis of saliva can provide telltale clues        was evident for many Americans. The application
!   Learn about the six major dental diseases.         of overall health or disease. The jawbones and          of science to improve diagnostic, treatment and
!   Discuss the connection between heart               their joints function like other musculoskeletal        prevention strategies has saved billions of dollars
    disease, diabetes and oral infections.             parts. The nervous system apparatus underlying          per year in the nation’s annual health bill. Even
!   Review some effective disease preventative         facial pain has its counterpart in nerves elsewhere     more significant, the result is that far fewer
    measures.                                          in the body. A thorough oral examination can            people are edentulous (toothless) today than a
!   Learn about craniofacial disorders.                detect signs of nutritional deficiencies as well as a   generation ago.
!   List factors affecting future dental health care   number of systemic diseases, including microbial
                                                                                                               The theme of prevention gained momentum as
    practices.                                         infections, immune disorders, injuries and some
                                                                                                               pioneering investigators and practitioners in the
                                                       cancers. Indeed, the phrase “the mouth is a
introduction                                                                                                   1950s and 1960s showed that not only dental
                                                       mirror” has been used to illustrate the wealth of
The realization that oral health can have a                                                                    caries but also periodontal diseases are bacterial
                                                       information that can be derived from examining
significant impact on the overall health and                                                                   infections. The researchers demonstrated that the
                                                       oral tissues.
well-being of the nation’s population has                                                                      infections could be prevented by increasing host
become a major issue in the world of science           New research is pointing to associations between        resistance to disease and reducing or eliminating
and research. Realizing the gains that have            chronic oral infections and heart and lung              the suspected microbial pathogens in the oral
been made in disease prevention, while                 diseases, stroke and low-birth-weight, premature        cavity. The applications of research discoveries
acknowledging that there are populations that          births. Associations between periodontal disease        have resulted in continuing improvements in the
suffer disproportionately from oral health             and diabetes have long been noted. Scientific           oral health of Americans, new approaches to the
problems, the purpose of this course is to help        reports assess these associations and explore           prevention and treatment of dental diseases, and
“define, describe and evaluate the interaction         mechanisms that might explain the oral-systemic         the growth of the science.
between oral health and health and well-being          disease connections.
                                                                                                               The significant role that scientists, dentists,
[quality of life], through the life span in the        The broadened meaning of oral health parallels          dental hygienists and other health professionals
context of changes in society.” Key elements to        the broadened meaning of health. In 1948,               have played in the prevention of oral disease and
be addressed are the determinants of health and        the World Health Organization expanded the              disability leads to a third theme of this course:
disease, with a primary focus on prevention and        definition of health to mean “a complete state          safe and effective disease prevention measures
“producing health” rather than “restoring health”;     of physical, mental and social well-being, and          exist that everyone can adopt to improve oral
a description of the burden of oral diseases and       not just the absence of infirmity.” It follows that     health and prevent disease. These measures
disorders in the nation; and the evidence for          oral health must also include well-being. Just as       include daily oral hygiene procedures and
actions to improve oral health to be taken across      we now understand that nature and nurture are           other lifestyle behaviors, community programs
the life span.                                         inextricably linked, and mind and body are both         such as community water fluoridation and
oral health                                            expressions of our human biology, so, too, we           tobacco cessation programs, and provider-based
The mouth includes not only the teeth and the          must recognize that oral health and general health      interventions such as the placement of dental
gums (gingiva) and their supporting tissues, but       are inseparable. We ignore signs and symptoms           sealants and examinations for common oral and
also the hard and soft palate, the mucosal lining      of oral disease and dysfunction to our detriment.       pharyngeal cancers.
of the mouth and throat, the tongue, the lips, the     Consequently, a second element of the course is
                                                                                                               General health risk factors, such as tobacco
salivary glands, the chewing muscles and the           that oral health is integral to general health. You
                                                                                                               use and poor dietary practices, also affect
upper and lower jaws. Equally important are the        cannot be healthy without good oral health; oral
                                                                                                               oral and craniofacial health. The evidence for
branches of the nervous, immune and vascular           health and general health are not separate entities.
                                                                                                               an association between tobacco use and oral
systems that animate, protect and nourish the oral     Oral health is a critical component of health and
                                                                                                               diseases has been clearly delineated in almost
tissues as well as provide connections to the brain    must be included in the provision of health care
                                                                                                               every surgeon general’s report on tobacco since
and the rest of the body. The genetic patterning of    and the design of community programs.
                                                                                                               1964, and the oral effects of nutrition and diet
development in utero further reveals the intimate      The wider meaning of oral health in no way              are presented in the surgeon general’s report on
relationship of the oral tissues to the developing     diminishes the relevance and importance of              nutrition (1988). All the dental professions can
brain and to the tissues of the face and head that     the two leading dental diseases, caries and the         play a role in reducing the burden of disease in
surround the mouth, structures whose location is       periodontal diseases. They remain common and            America by calling attention to these and other
captured in the word craniofacial.                     widespread, affecting nearly everyone at some           risk factors and suggesting appropriate actions.
A key element to discuss is that oral health means     point in the life span. What has changed is what
                                                                                                               Clearly, promoting health and preventing diseases
much more than healthy teeth. It means being           we can do about them.
                                                                                                               are concepts the American people have taken
free of chronic oral-facial pain conditions, oral      Researchers in the 1930s discovered that people         to heart. As a nation, we hope to eliminate
and pharyngeal (throat) cancers, oral soft tissue      living in communities with naturally fluoridated        disparities in health and prevent oral diseases,
lesions, birth defects such as cleft lip and palate,   water supplies had fewer dental caries than             cancer, birth defects, AIDS and other devastating
and scores of other diseases and disorders that        people drinking unfluoridated water. But not until      infections; mental illness and suicide; and the
affect the oral, dental and craniofacial tissues,      the end of World War II were the investigators          chronic diseases of aging. To live well into old
collectively known as the craniofacial complex.        able to design and implement the community              age free of pain and infirmity and with a high
These are tissues whose functions we often take        clinical trials that confirmed their observations       quality of life is the American dream.
for granted, yet they represent the very essence       and launch a better approach to the problem of
of our humanity. They allow us to speak and                                                                    Scientists today take that dream seriously in
                                                       dental caries: prevention. Soon after, adjusting
smile; sigh and kiss; smell, taste, touch, chew and                                                            researching the intricacies of the craniofacial
                                                       the fluoride content of community water supplies
swallow; cry out in pain; and convey a world of                                                                complex. They are using an ever-growing array

Page 64                                                                                                                                                 Elite CME
of sophisticated analytic tools and imaging           counseling and other health promotion efforts        (mechanoreceptors), hot and cold temperatures
systems to study normal function and diagnose         into their practices.                                (thermoreceptors) and pain (nociceptors). The
disease. They are completing the mapping and                                                               dense concentration of these receptors in the
sequencing of human, animal, microbial and
                                                      There are profound and consequential                 facial skin, joints, muscle and oral soft tissues,
plant genomes, the better to understand the           oral health disparities within the u.s.              relayed to an image of the body mapped onto
complexities of human development, aging and          population                                           the sensory cortex of the brain, accounts for
pathological processes. They are growing cell         Disparities for various oral conditions may          the finesse with which we can discriminate the
lines, synthesizing molecules and using a new         relate to income, age, sex, race or ethnicity, or    qualities and precise location of these sensations.
generation of biomaterials to revolutionize tissue    medical status. Although common dental diseases      In particular, the periodontal ligament, which
repair and regeneration. More than ever before,       are preventable, not all members of society are      anchors the teeth in the jaws, is a tactilely
they are working in multidisciplinary teams to        informed about or able to avail themselves of        sensitive tissue providing important feedback
bring new knowledge and expertise to the goal         appropriate oral-health-promoting measures.          with regard to mastication and dental occlusion.
of understanding complex human diseases and           Similarly, not all health providers may be aware     As a test of this sensibility, a human hair placed
disorders.                                            of the services needed to improve oral health. In    between the tips of the fingers will rarely be
                                                      addition, oral health care is not fully integrated   sufficient to stimulate the nerve endings, but the
oral diseases and disorders in and of                 into many care programs. Social, economic            same hair placed between the lips or incisors will
themselves affect health and well-being               and cultural factors and changing population         instantly be felt.
throughout life                                       demographics affect how health services are
                                                                                                           Pain and thermal sensitivity in the teeth are
The burden of oral problems is extensive and may delivered and used, and how people care for
                                                      themselves. Reducing disparities requires wide-      transmitted through nerve endings in the pulp.
be particularly severe in vulnerable populations.
                                                                                                           Because the pulp is in a narrow canal composed
It includes the common dental diseases and other ranging approaches that target populations at
                                                                                                           of connective tissue, blood vessels and nerves
oral infections such as cold sores and candidiasis highest risk for specific oral diseases and involves
                                                                                                           and surrounded by hard tissue, any infection or
that can occur at any stage of life, as well as birth improving access to existing care. One approach
                                                      includes making dental insurance more available      inflammation that would normally cause tissue
defects in infancy and the chronic facial pain
                                                      to Americans. Public coverage for dental care is     to swell creates pressure on the pulpal nerves.
conditions and oral cancers seen in later years.
                                                      minimal for adults, and programs for children        That pressure, along with bacterial or immune
Many of these conditions and their treatments
                                                      have not reached the many eligible beneficiaries.    system products that stimulate the nerve endings,
may undermine self-image and self-esteem,
                                                                                                           produces the severe pain of pulpal infections.
discourage normal social interaction, cause other
                                                      The mouth reflects general health and
health problems and lead to chronic stress and                                                             Neuroscientists have long studied oral-facial
depression as well as incur great financial cost.     well-being                                           pain, not only because of its importance in
They may also interfere with vital functions such The mouth is a readily accessible and visible part       oral disease, but also because it provides an
as breathing, food selection, eating, swallowing      of the body and provides health care providers
                                                                                                           accessible model of pain elsewhere in the body.
and speaking and with activities of daily living      and individuals with a window on their general
                                                                                                           These investigations have greatly enriched our
such as work, school and family interactions.         health status. As the gateway of the body, the
                                                                                                           understanding of the basic mechanisms of pain
                                                      mouth senses and responds to the external world
                                                                                                           perception and modulation. They have helped
safe and effective measures exist to                  and at the same time reflects what is happening
                                                                                                           delineate the complex pathways and multiple
prevent the most common dental                        deep inside the body. The mouth may show
                                                                                                           transmitters that convey pain signals to the brain
diseases – dental caries and periodontal              signs of nutritional deficiencies and serve as an
                                                                                                           and spinal cord, as well as the mechanisms
diseases                                              early warning system for diseases such as HIV
                                                                                                           and molecules that can modulate and inhibit
Community water fluoridation is safe and              infection and other immune system problems.
                                                                                                           nociceptive input. These studies have also
effective in preventing dental caries in both         The mouth can also show signs of general
                                                                                                           exploited new brain-imaging techniques to
children and adults. Water fluoridation benefits      infection and stress. As the number of substances
                                                                                                           confirm the wide distribution of pain pathways
all residents served by community water               that can be reliably measured in saliva increases,
                                                                                                           and relay centers in the cerebral hemispheres and
supplies regardless of their social or economic       it may well become the diagnostic fluid of choice,
status. Professional and individual measures,         enabling the diagnosis of specific disease as well
                                                      as the measurement of the concentration of a         This research has generated new approaches
including the use of fluoride mouth rinses, gels,
                                                      variety of drugs, hormones and other molecules       to the control of acute and chronic pain. These
dentifrices and dietary supplements and the
                                                      of interest. Cells and fluids in the mouth may       approaches include the use of nonsteroidal,
application of dental sealants, are additional
                                                      also be used for genetic analysis to help uncover    anti-inflammatory drugs and long-acting local
means of preventing dental caries. Gingivitis
                                                      risks for disease and predict outcomes of medical    anesthetics for acute oral and dental pain, and the
can be prevented by good personal oral hygiene
                                                      treatments.                                          use of more potent drugs, drug combinations and
practices, including brushing and flossing.
                                                                                                           other kinds of therapies to treat chronic pain.
                                                      oral diseases and conditions are
Lifestyle behaviors that affect general                                                                    Researchers have emphasized the importance of
                                                      associated with other health problems
health such as tobacco use, excessive                                                                      adequate pain control in patients with chronic
                                                      Oral infections can be the source of systemic
alcohol use and poor dietary choices                  infections in people with weakened immune            pain conditions.
affect oral and craniofacial health as well           systems, and oral signs and symptoms often are       Otherwise, the constant barrage of signals can
These individual behaviors are associated with        part of a general health condition. Associations     effect long-term changes in the brain that actually
increased risk for craniofacial birth defects, oral   between chronic oral infections and other health     worsen the pain (producing hyperalgesia)
and pharyngeal cancers, periodontal disease,          problems, including diabetes, heart disease          and cause normally nonpainful stimuli to
dental caries and candidiasis, among other oral       and adverse pregnancy outcomes, have also            be perceived as painful (a condition called
health problems. Opportunities exist to expand        been reported. Ongoing research may uncover          allodynia). Unrelieved chronic pain may also
the oral disease prevention and health promotion      mechanisms that strengthen the current findings      suppress the immune system.
knowledge and practices of the public through         and explain these relationships.
community programs and in health care settings.                                                            Recently, investigators discovered a link between
All health care providers can play a role in          Touch, temperature and pain                          certain taste sensations, pain and temperature.
promoting healthy lifestyles by incorporating         The mouth also contains large numbers of             Their findings indicate that capsaicin, the
tobacco cessation programs, nutritional               nerve endings, similar to those found elsewhere      ingredient that makes hot peppers taste hot, binds
                                                      in the body, that are sensitive to touch             to a receptor on the surface of nociceptors that

Elite CME                                                                                                                                              Page 65
also responds to noxious heat. The researchers         to the lungs for respiration or the esophagus for      The bacteria colonizing the mouth are known as
have cloned the gene for the capsaicin receptor        further digestion and passage to the stomach.          the oral flora. They form a complex community
(called vanilloid receptor 1); they believe it is      This is a point of vulnerability: Should food or       that adheres to tooth surfaces in a gelatinous mat,
involved in several chronic pain conditions,           some other obstruction lodge in the airway, it         or biofilm, commonly called dental plaque. A
especially those where inflammation plays a role,      could lead to death by asphyxiation.                   cariogenic biofilm at a single tooth may contain
such as viral and diabetic neuropathy, rheumatoid                                                             one-half billion bacteria, of which mutans
                                                       Externally, the oral cavity is bounded by the
arthritis and oral mucositis pain caused by cancer                                                            streptococci are critical components.
                                                       maxilla (the upper jaw bone), attached to the
chemotherapy or radiation.
                                                       cranium, and the mandible (the lower jaw),             These bacteria are able to ferment sugars and
There is evidence that the prevalence of a             attached to the temporal bone of the skull by the      other carbohydrates to form lactic and other
number of pain conditions varies by gender             temporomandibular joint.                               acids. Repeated cycles of acid generation can
and that men and women respond differently                                                                    result in the microscopic dissolution of minerals
to different analgesic drugs. These findings
                                                       oral invaders                                          in tooth enamel and the formation of an opaque
                                                       As the gateway to the body, the mouth is
have prompted studies aimed at determining                                                                    white or brown spot under the enamel surface.
                                                       challenged by a constant barrage of invaders –
whether there are sex differences in pain anatomy                                                             Frequency of carbohydrate consumption, physical
                                                       bacteria, viruses, parasites, fungi. Thus infectious
and neurochemistry and whether (and how)                                                                      characteristics of food (i.e., stickiness), and
                                                       diseases, notably dental caries and periodontal
nociception is affected by sex hormones.                                                                      timing of food intake also play a role.
                                                       diseases, predominate among the ills that can
speech                                                 compromise oral health. Injuries take their toll       The essential role of bacteria in caries initiation
Human speech and language are the faculties that       as well, with the face and head particularly           was established in landmark experiments in the
most distinguish us from other higher primates;        vulnerable to sports injuries, motor vehicle           1950s. Investigators observed that germ-free
they are also the links that bind people together in   crashes, violence and abuse. Less common but           animals fed high-sugar diets remained caries-
diverse social groups and cultures.                    very serious are oral and pharyngeal cancers,          free until the introduction of mutans streptococci
                                                       with a five-year survival rate of hardly better        (a particular group of bacterial strains having a
Central to speech are laryngeal mechanisms                                                                    number of common characteristics and which
                                                       than 50 percent. Birth defects and developmental
involving the vocal cords. Equally critical are the                                                           adhere tightly to the tooth). Later experiments
                                                       disorders frequently affect the craniofacial
respiratory system, the pharynx and the nasal and                                                             demonstrated the transmissibility of the
                                                       complex. These appear most commonly as
oral cavities. The tongue is the most important                                                               bacteria from mother to litter and from caries-
                                                       isolated cases of cleft lip or palate, but clefting
structure of the peripheral speech mechanisms,                                                                infected to uninfected cage-mates. Species of
                                                       or other craniofacial defects can also be part
working in conjunction with the lips, teeth and                                                               Lactobacillus, Actinomyces and other acid-
                                                       of complex hereditary diseases or syndromes.
palate to produce a rich repertoire of sounds.                                                                producing streptococci within the plaque may
                                                       Additionally, acute and chronic pain can affect
Abnormalities in oral structures, from missing         the oral-facial region, particularly in and around     also contribute to the process.
or malformed teeth and malocclusion to cleft           the temporomandibular (jaw) joint, and accounts        If the caries infection in enamel goes unchecked,
lip and palate, can seriously affect articulation.     for a disproportionate amount of all types of pain     the acid dissolution can advance to form a
The movements of speech are orchestrated               that drive individuals to seek health care.            cavity that can extend through the dentin (the
by brain centers that coordinate the muscles                                                                  component of the tooth located under the enamel)
                                                       Many systemic diseases such as diabetes,
of mastication, facial expression and jaw                                                                     to the pulp tissue, which is rich in nerves and
                                                       arthritis, osteoporosis and AIDS as well as
movements.                                                                                                    blood vessels. The resulting toothache can be
                                                       therapies for systemic diseases can directly or
Hearing impairments can also affect speech.            indirectly compromise oral tissues. The World          severe and often is accompanied by sensitivity
To learn to speak, children must be able to hear       Health Organization’s International Classification     to temperature and sweets. Treatment requires
others and monitor the feedback from their own         of Diseases and Stomatology currently lists more       endodontic (root canal) therapy. If untreated, the
voices. Congenital deafness and the serious            than 120 specific diseases, distributed in 10 or       pulp infection can lead to abscess, destruction
hearing defects associated with some craniofacial      more classes, that have manifestations in the oral     of bone and spread of the infection via the
                                                       cavity.                                                bloodstream.
syndromes can severely compromise speech
acquisition.                                           Dental and periodontal infections                      Dental caries can occur at any age after teeth
                                                       The most common oral diseases are dental caries        erupt. Particularly damaging forms can begin
The oral cavity                                                                                               early, when developing primary teeth are
The mouth is the gateway to the body, performing       and the periodontal diseases. Individuals are
                                                       vulnerable to dental caries throughout life, with      especially vulnerable. This type of dental caries
dozens of functions that place high demands                                                                   is called early childhood caries (ECC). Some
on its unique hard and soft tissues. The point of      85 percent of adults aged 18 and older affected.
                                                       Periodontal diseases are most often seen in            six out of 10 children in the United States have
entry is the lips, which open into the oral cavity.                                                           one or more decayed or filled primary teeth
The cheeks form the sides of the cavity, and the       maturity, with the majority of adults experiencing
                                                       some signs and symptoms by the mid-30s.                by age 5. ECC may occur in children who
roof is formed by the palate, which separates                                                                 are given pacifying bottles of juice, milk or
the mouth from the nose above and the pharynx          Certain rare forms of periodontal disease affect
                                                       young people. The major oral health success            formula to drink during the day or overnight.
(throat) behind. The anterior palate is hard,                                                                 The sugar contents pool around the upper front
formed by underlying bone, and serves as a             story of the past half century is that both caries
                                                       and periodontal diseases can be prevented by           teeth, mix with cariogenic bacteria and give rise
shield against trauma to the face and head. The                                                               to rapidly progressing destruction. Other risk
posterior palate is soft, composed of muscles          a combination of individual, professional and
                                                       community measures.                                    factors for ECC include arrested development
and connective tissue that blend into the walls                                                               of tooth enamel, chronic illness, altered salivary
of the pharynx. Hanging from the rear of the           Dental caries                                          composition and volume (resulting from the
soft palate is the uvula, a mass of muscle and         The word caries derives from the Latin for             use of certain medications or malnourishment),
connective tissue. Under the tongue is the floor       rotten, and many cultures early on posited a tooth     mouth breathing and blockage of saliva flow in a
of the mouth, composed primarily of muscle and         worm as the cause of this rottenness. By the 20th      bottle-fed infant.
salivary glands. The paired tonsils and adenoids,      century, caries came to describe the condition
important components of the immune system,                                                                    Although there have been continuing reductions
                                                       of having holes in the teeth – cavities. This
lie at the sides of the palate and within the                                                                 in dental caries in permanent teeth among
                                                       description, although not incorrect, is misleading.
nasopharynx, respectively.                                                                                    children and adolescents over the past few
                                                       In actuality, a cavity is a late manifestation of a
                                                                                                              decades, caries prevalence in the primary
The pharynx opens into channels leading either         bacterial infection.
                                                                                                              dentition may have stabilized or increased
Page 66                                                                                                                                                 Elite CME
slightly in some population groups. Reductions        are infected before their first birthday, around         may occur for other reasons as well).
in caries in permanent teeth also have been           the time the first incisors emerge. However, one        Patients should realize that the gingival
proportionately greater on the smooth surfaces        study found the median age of acquisition to             inflammation and bone destruction are largely
rather than on the pit-and-fissure surfaces           be 26 months, coinciding with the emergence              painless. Hence, people may wrongly assume
characteristic of chewing surfaces. The gingival      of the primary molars. DNA fingerprinting has            that painless bleeding after teeth cleaning
tissues tend to recede over time, exposing the        demonstrated that the source of transmission is          is insignificant, although this may be a
tooth root to cariogenic bacteria that can cause      usually the mother.                                      symptom of progressing periodontitis in that
root caries. An important risk factor for root                                                                 patient.
                                                      It is not clear why some individuals are more
caries in older people is the use of medications                                                           Certain factors increase the risk for periodontal
                                                      susceptible and others more resistant to
that inhibit salivary flow, leading to dry mouth                                                           disease:
                                                      caries. Genetic differences in the structure and
(xerostomia).                                                                                               Smoking.
                                                      biochemistry of enamel proteins and crystals
Saliva contains components that can directly          as well as variations in the quality and quantity     Diabetes.
attack cariogenic bacteria, and it is also rich in    of saliva and in immune defense mechanisms            Poor oral hygiene.
calcium and phosphates that help to remineralize      are among the factors under study. Analysis of        Stress.
tooth enamel. Demineralization of enamel              mutans streptococci genomes may also shed light,      Heredity.
occurs when pH levels fall as a result of acid        indicating which species are particularly virulent    Crooked teeth.
production by bacteria. It can be reversed            and which genes contribute to that virulence.         Underlying immunodeficiencies – i.e., AIDS.
at early stages if the local environment can                                                                Fillings that have become defective.
                                                      Even the most protective genetic endowment
counteract acid production, restoring pH to                                                                 Taking medications that cause dry mouth.
                                                      and developmental milieu are unlikely to confer
neutral levels. Remineralization can occur                                                                  Bridges that no longer fit properly.
                                                      resistance to decay in the absence of positive
through the replacement of lost mineral (calcium                                                            Female hormonal changes, such as with
                                                      personal behaviors. These include sound dietary
and phosphates) from the stores in saliva.                                                                     pregnancy or the use of oral contraceptives.
                                                      habits and good oral hygiene, including the use
Fluoride in saliva and dental plaque and the
                                                      of fluorides, and seeking professional care. There   Prevention
buffering capacity of saliva also contribute to
                                                      are indications, however, that some destructive      Daily oral hygiene measures to prevent
this process. Indeed, it is now believed that
                                                      oral habits are on the rise, such as the use of      periodontal disease include:
fluoride exerts its chief caries-preventive effect
                                                      smokeless (spit) tobacco products by teenage          Brushing properly on a regular basis (at least
by facilitating remineralization. Several studies
                                                      boys. Although the chief concern here lies in the        twice daily), with the patient attempting to
have demonstrated that remineralization results
                                                      long-term risk for oral cancers, spit tobacco that       direct the toothbrush bristles underneath the
in an increase in tooth hardness and mineral
                                                      contains high levels of sugar is also associated         gumline to help disrupt the bacterial growth
content, rendering the tooth surface more
                                                      with increased levels of decay of both crown and         and formation of subgingival plaque.
resistant to subsequent acid attack. Overt caries
                                                      root surfaces.                                        Flossing daily and using interdental brushes
lesions develop when there is insufficient time for
                                                                                                               (if there is a sufficiently large space between
remineralization between periods of acidogenesis      Periodontal diseases                                     teeth), as well as cleaning behind the last
or when the saliva production is compromised.         Like dental caries, the periodontal diseases are
                                                                                                               tooth, the third molar, in each quarter.
Over 400 medications list dry mouth as a              infections caused by bacteria in the biofilm
                                                                                                            Using an antiseptic mouthwash. Chlorexidine
side effect, notably some antidepressants,            (dental plaque) that forms on oral surfaces. The
                                                                                                               gluconate based mouthwash in combination
antipsychotics, antihistamines, decongestants,        basic division in the periodontal diseases is
                                                                                                               with careful oral hygiene may cure gingivitis,
antihypertensives, diuretics and anti-Parkinsonian    between gingivitis, which affects the gums, and
                                                                                                               although they cannot reverse any attachment
drugs. The effects of xerostomia may be               periodontitis, which may involve all of the soft
                                                                                                               loss due to periodontitis.
particularly severe in cancer patients receiving      tissue and bone supporting the teeth. Gingivitis
                                                                                                            Using a “soft” toothbrush to prevent damage
radiation to the head or neck because the rays can    and milder forms of periodontitis are common
                                                                                                               to tooth enamel and sensitive gums.
destroy salivary gland tissue rather than simply      in adults. The percentage of individuals with
                                                                                                            Using periodontal trays to maintain dentist-
inhibiting salivary secretion.                        moderate to severe periodontitis, in which the
                                                                                                               prescribed medications at the source of
                                                      destruction of supporting tissue can cause the
The professional application of dental sealants                                                                the disease. The use of trays allows the
                                                      tooth to loosen and fall out, increases with age.
(plastic films coated onto the chewing surfaces                                                                medication to stay in place long enough to
of teeth) is an important caries-preventive           signs and symptoms                                       penetrate the biofilms where the bacteria are
measure that complements the use of fluorides.        In the early stages, periodontitis has very few          found.
The films prevent decay from developing in the        symptoms, and in many individuals the disease         Regular dental check-ups and professional
pits and fissures of teeth, channels that are often   has progressed significantly before they seek            teeth cleaning as required. Dental check-ups
inaccessible to brushing and where fluoride may       treatment. Symptoms may include the following:           serve to monitor the person’s oral hygiene
be less effective.                                     Redness or bleeding of gums while brushing             methods and levels of attachment around
                                                          teeth, using dental floss or biting into hard        teeth, identify any early signs of periodontitis,
The rate of caries progression through enamel
                                                          food, for example, apples (though this may           and monitor response to treatment.
is relatively slow and may be slower in patients
who have received regular fluoride treatment or           occur even in gingivitis, where there is no      Typically dental hygienists (or dentists) use
who consume fluoridated water. Because a large            attachment loss).                                special instruments to clean (debride) teeth below
percentage of enamel lesions remain unchanged          Gum swelling that recurs.                          the gumline and disrupt any plaque growing
over periods of three to four years, and because       Halitosis, or bad breath, and a persistent         below the gumline. This is a standard treatment
progression rates through dentin are comparably           metallic taste in the mouth.                     to prevent any further progress of established
slow, the application of infection control and         Gingival recession, resulting in apparent          periodontitis. Studies show that after such a
monitoring procedures to assess caries risk status,       lengthening of teeth. (This may also be          professional cleaning (periodontal debridement),
lesion activity status, evidence of lesion arrest         caused by heavy-handed brushing or with a        bacteria and plaque tend to grow back to pre-
and evidence of lesion remineralization over              stiff toothbrush.)                               cleaning levels after about three to four months.
extended periods of time is recommended.               Deep pockets between the teeth and the             Hence, in theory, cleanings every three to four
                                                          gums (pockets are sites where the attachment     months might be expected to also prevent the
Experts believe that the earlier mutans                   has been gradually destroyed by collagen-        initial onset of periodontitis. However, analysis
streptococci are acquired in infancy, the higher          destroying enzymes, known as collagenases).      of published research has reported little evidence
the caries risk. Most studies indicate that infants    Loose teeth, in the later stages (though this
Elite CME                                                                                                                                               Page 67
either to support this or the intervals at which        bone loss over time. This is especially true in        surgery to access the depths of the pockets and
this should occur. Instead, it is advocated that        molar tooth sites where furcations (areas between      perhaps even change the pocket depths so that
the interval between dental check-ups should be         the roots) have been exposed.                          they become 3 mm or less in depth and can once
determined specifically for each patient between                                                               again be properly cleaned by the patient at home
every three to 24 months.
                                                        Periodontal surgery                                    with his or her toothbrush.
                                                        If nonsurgical therapy is found to have been
Nonetheless, the continued stabilization of a           unsuccessful in managing signs of disease              If a patient has 7 mm or deeper pockets
patient’s periodontal state depends largely, if not     activity, periodontal surgery may be needed to         around the teeth, then he or she would likely
primarily, on the patient’s oral hygiene at home        stop progressive bone loss and regenerate lost         risk eventual tooth loss over the years. If this
as well as on the go. Without daily oral hygiene,       bone where possible. There are many surgical           periodontal condition is not identified and the
periodontal disease will not be overcome,               approaches used in treatment of advanced               patient remains unaware of the progressive nature
especially if the patient has a history of extensive    periodontitis, including open flap debridement,        of the disease then, years later, he or she may be
periodontal disease.                                    osseous surgery, guided tissue regeneration and        surprised that some teeth will gradually become
                                                        bone grafting. The goal of periodontal surgery         loose and may need to be extracted, sometimes
A contributing cause may be low selenium in
                                                        is access for definitive calculus removal and          due to a severe infection or even pain.
the diet: “Results showed that selenium has the
strongest association with gum disease, with low        surgical management of bony irregularities             According to the Sri Lankan Tea Labourer study,
levels increasing the risk by 13-fold.”                 that have resulted from the disease process            in the absence of any oral hygiene activity,
                                                        to reduce pockets as much as possible. Long-           approximately 10 percent will suffer from severe
The cornerstone of successful periodontal               term studies have shown that in moderate to            periodontal disease with rapid loss of attachment
treatment starts with establishing excellent oral       advanced periodontitis, surgically treated cases       (more than 2 mm/year). Eighty percent will
hygiene. This includes twice daily brushing with        often have less ongoing breakdown over time,           suffer from moderate loss (1-2 mm/year), and the
daily flossing. The use of an interdental brush         and when coupled with a regular post-treatment         remaining 10 percent will not suffer any loss.
(called a proxi-brush) also is helpful if space         maintenance regimen are successful in nearly
between the teeth allows. Persons with dexterity        halting tooth loss in nearly 85 percent of patients.   Alternative treatments
problems such as arthritis may find oral hygiene                                                               Periodontitis has an inescapable relationship
to be difficult and may require more frequent           Maintenance                                            with subgingival calculus (tartar). The first step
professional care and the use of a powered              Once successful periodontal treatment has              in any procedure is to eliminate calculus under
toothbrush. Persons with periodontitis must             been completed, with or without surgery, an            the gumline, as it houses destructive anaerobic
realize that it is a chronic inflammatory disease       ongoing regimen of periodontal maintenance             bacteria that consume bone, gum and cementum
and that a lifelong regimen of excellent hygiene        is required. This involves regular checkups and        (connective tissue) for food.
and professional maintenance care with a dentist/       detailed cleanings every three months to prevent
                                                        repopulation of periodontitis-causing bacteria,        Most alternative “at-home” gum disease
hygienist or periodontist is required to maintain
                                                        and to closely monitor affected teeth so that          treatments involve injecting antimicrobial
affected teeth.
                                                        early treatment can be rendered if disease recurs.     solutions, such as hydrogen peroxide, into
initial therapy                                         Usually periodontal disease exists due to poor         periodontal pockets via slender applicators or
Removal of bacterial plaque and calculus is             plaque control, so if brushing techniques are not      oral irrigators. This process disrupts anaerobic
necessary to establish periodontal health. The          modified, a periodontal recurrence is probable.        bacteria colonies and is effective at reducing
first step in the treatment of periodontitis involves                                                          infections and inflammation when used daily.
nonsurgical cleaning below the gumline with             Assessment and prognosis                               There are any number of potions and elixirs
a procedure called scaling and debridement.             Dentists and dental hygienists “measure”               that are commercially available that are
In the past, root planing was used (removal             periodontal disease using a device called a            functionally equivalent to hydrogen peroxide,
of cemental layer as well as calculus). This            periodontal probe. This is a thin measuring stick      but at substantially higher cost. These treatments,
procedure involves use of specialized curettes          that is gently placed into the space between           however, do not address calculus formations and
to mechanically remove plaque and calculus              the gums and the teeth and slipped below the           are therefore short-lived, as anaerobic bacteria
from below the gumline, and may require                 gumline. If the probe can slip more than 3 mm          colonies quickly regenerate in and around
multiple visits and local anesthesia to adequately      below the gumline, the patient is said to have         calculus.
complete. In addition to initial scaling and root       a “gingival pocket” around that tooth. This is
planing, it may also be necessary to adjust the         somewhat of a misnomer, as any depth is in
occlusion (bite) to prevent excessive force on          essence a pocket, which in turn is defined by its
teeth with reduced bone support. It also may be         depth, i.e., a 2 mm pocket or a 6 mm pocket.
necessary to complete any other dental needs,           However, it is generally accepted that pockets
such as replacement of rough, plaque retentive          are self-cleansable (at home, by the patient,
restorations, closure of open contacts between          with a toothbrush) if they are 3 mm or less in
teeth and any other requirements diagnosed at the       depth. This is important because if a pocket is
initial evaluation.                                     deeper than 3 mm around the tooth, at-home
                                                        care will not be sufficient to cleanse the pocket,
Re-evaluation                                           and professional care should be sought. When
Multiple clinical studies have shown that               the pocket depths reach 6 and 7 mm in depth,
nonsurgical scaling and root planing is usually         the hand instruments and cavitrons used by the         In a new field of study, calculus formations are
successful in periodontal pocket depths no greater      dental professionals may not reach deeply enough       addressed on a more fundamental level. At the
than 4-5 mm. It is necessary for the dentist or         into the pocket to clean out the bacterial plaque      heart of the formation of subgingival calculus,
hygienist to check four to six weeks after the          that cause gingival inflammation. In such a            growing plaque formations starve out the lowest
initial scaling and root planing to determine           situation the bone or the gums around that tooth       members of the community, which calcify into
whether the treatment was successful in reducing        should be surgically altered or it will always         calcium phosphate salts of the same shape and
pocket depths and eliminating inflammation. It          have inflammation, which will likely result in         size of the original, organic bacilli. Calcium
has been found that pocket depths that remain           more bone loss around that tooth. An additional        phosphate salts (unlike calcium phosphate, the
after initial therapy of greater than 5-6 mm with       way to stop the inflammation would be for the          primary component in teeth) are ionic and adhere
bleeding upon probing are indicative of continued       patient to receive subgingival antibiotics (such as    to tooth surfaces via electrostatic attraction.
active disease and will very likely show further        minocycline) or undergo some form of gingival          Smaller, free floating calcium phosphate salt

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particles are equally attracted to the same areas,    Ranney (1989) notes, “The complexity of the          resistance, the clinical attachment loss of the
as are additional calcified bacteria, growing         results defies any attempt to define a discrete      periodontal ligament measured from a fixed
calculus formations as unorganized, yet strong        group clearly and consistently associated with       point on the tooth (usually the cemento-enamel
“brick and mortar” matrices. The microscopic          gingivitis.”                                         junction), and the loss of adjacent alveolar bone
voids in calculus formations house new anaerobic                                                           as measured by x-ray. Severity is determined by
                                                      Gingival inflammation may be influenced by
bacteria, as does the top diseased layer.                                                                  the rate of disease progression over time and the
                                                      steroid hormones, occurring as puberty gingivitis,
                                                                                                           response of the tissues to treatment.
Because the root cause of subgingival calculus        pregnancy gingivitis, and gingivitis associated
development is ionic attraction, it was               with birth control medication or steroid therapy.    Adult periodontitis often begins in adolescence
hypothesized that the introduction of oppositely      The presence of steroid hormones in tissues          but is usually not clinically significant until the
charged particles around the formations might         adjacent to biofilm apparently encourages            mid-30s. Prevalence and severity increase but
chelate calcium phosphate salt components away        the growth of certain bacteria and triggers an       do not accelerate with age. One view proposes
from the matrix, thus actually reducing the size of   exaggerated response to biofilm accumulation.        that destruction occurs at a specific site during
subgingival calculus formations.                      Again, thorough oral hygiene can control this        a defined period, after which the disease goes
                                                      response.                                            into remission. The current view is that the
To accomplish this, a sequestering agent solution
                                                                                                           disease process may not be continuous but rather
comprised partly of sodium tripolyphosphate           Certain prescription drugs can also lead
                                                                                                           progresses in random bursts in which short
(STPP) and sodium flouride (charge-1) was tested      to gingival overgrowth and inflammation.
                                                                                                           periods of breakdown of periodontal ligament
on a patient with burnished and new subgingival       These include the antiepileptic drug
                                                                                                           and bone alternate with periods of quiescence.
calculus at a depth of 6 mm. The patient              phenytoin (Dilantin); cyclosporin, used for
                                                                                                           These episodes occur randomly over time and at
delivered the solution using an oral irrigator        immunosuppressive therapy in transplant
                                                                                                           random sites in the mouth. Part of the difficulty
once a day for 60 days. The results of this test      patients; and various calcium channel blockers
                                                                                                           in determining the pattern of progression reflects
were the successful elimination of all calculus       used in heart disease. Treatment often requires
                                                                                                           variation in the sensitivity of the instruments used
formations studied. This test was conducted using     surgical removal of the excess tissue followed by
                                                                                                           to measure the loss of soft tissue and bone. The
a subgingival endoscopic camera (perioscope) by       appropriate personal and professional oral health
                                                                                                           latest generation of probes finds evidence of both
an independent periodontist.                          care.
                                                                                                           continuous and multiple-burst patterns of loss in
This alternative treatment keeps subgingival          A form of gingivitis common 50 years ago             different patients and at different times.
calculus at bay, in concert with traditional          but relatively rare today is acute necrotizing
periodontal treatments. In this way, periodontitis    ulcerative gingivitis, also known as Vincent’s
may be controlled by the patient, with complete       infection or trench mouth. This aggressive
restoration of dental health being a collaborative    infection is characterized by destruction of the
effort between the patient and the dental             gingiva between the teeth, spontaneous bleeding,
professional.                                         pain and oral odor. People under extreme stress
                                                      have an increased susceptibility. Spirochetes and
gingivitis                                            other bacteria have been found in the connective
Gingivitis is an inflammation of the gums             tissue of those affected. An association between
characterized by a change in color from normal        smoking and this type of gingivitis is well
pink to red, swelling, bleeding and often                                                                  This drawing shows a dentist using a probe to
                                                      recognized and was demonstrated as early as                check for inflammatory pockets.
sensitivity and tenderness. These changes             1946. This condition has been seen in some
result from an accumulation of biofilm along          HIV-positive patients. Treatment requires            Most researchers agree that periodontitis results
the gingival margins and the immune system’s          a combination of professional periodontal            from a mixed infection, but that a particular
inflammatory response to the release of               treatment and antibacterial therapy along with       group of gram-negative bacteria are key to the
destructive bacterial products. The early changes     professional smoking cessation assistance as         process and markedly increase in the subgingival
of gingivitis are reversible with thorough            appropriate.                                         plaque. The bacteria most frequently cited are
toothbrushing and flossing to reduce plaque.                                                               Porphyromonas gingivalis, Prevotella intermedia,
Without adequate oral hygiene, however,               Adult periodontitis                                  Bacteroides forsythus, Treponema denticola
these early changes can become more severe,           The most common form of adult periodontitis is       and Actinobacillus actinomycetemcomitans.
with infiltration of inflammatory cells and           described as general and moderately progressing;     Their role in disease initiation and progression
establishment of a chronic infection. Biofilm         a second form is described as rapidly progressing    is determined in part by their virulence factors.
on tooth surfaces opposite the openings of the        and severe, and is often resistant to treatment.     These include the ability to colonize subgingival
salivary glands often mineralizes to form calculus    The moderately progressive adult form is             plaque, generate products that can directly
or tartar, which is covered by unmineralized          characterized by a gradual loss of attachment        injure tissues and elicit an inflammatory or
biofilm – a combination that can exacerbate local     of the periodontal ligament to the gingiva and       immune response. The potentially noxious
inflammatory responses. A gingival infection may      bone along with loss of the supporting bone.         bacterial products include hydrogen sulfide,
persist for months or years, yet never progress to    It is most often accompanied by gingivitis.          polyamines, the fatty acids butyrate and
periodontitis.                                        It is not necessarily preceded by gingivitis,        propionate, lipopolysaccharide (also known
                                                      but the gingivitis-related biofilm often seeds       as endotoxin), and a number of destructive
Gingival inflammation does not appear until the
                                                      the subgingival plaque. The destruction of           enzymes. The interaction of this arsenal with
biofilm changes from one composed largely of
                                                      periodontal ligament and bone results in the         the host response is at the core of periodontal
gram-positive streptococci (which can live with
                                                      formation of a pocket between the tooth and          pathology, (Socransky and Haffajee 1991, 1992).
or without oxygen) to one containing gram-
                                                      adjacent tissues, which harbors subgingival          Sequencing of the genomes of several key
negative anaerobes (which cannot live in the
                                                      plaque. The calculus formed in the pocket by         periodontal pathogens is under way and should
presence of oxygen). Numerous attempts have
                                                      inflammatory fluids and minerals in adjacent         provide further insight into these pathogens as
been made to pinpoint which microorganisms
                                                      tissues is especially damaging.                      well as catalyze new treatment approaches.
in the supragingival (above the gumline)
plaque are the culprits in gingivitis. Frequently     The severity of periodontal disease is determined    Delicate balances
mentioned organisms include Fusobacterium             through a series of measurements, including the      Neutrophils (a type of white blood cell) and
nucleatum, Veillonella parvula, and species           extent of gingival inflammation and bleeding,        antibodies are the major immune defenses
of Campylobacter and Treponema. But as                the probing depth of the pocket to the point of      against bacterial attack. Neutrophils move to

Elite CME                                                                                                                                              Page 69
the site of infection, where they engulf bacteria       additional factors as increasing age, infrequent      in different subjects. It is not known whether
and elaborate antibacterial agents and enzymes          dental visits, low education level, low income,       variations in pathogenicity of the bacteria, defects
to destroy bacteria. Although stimulation of            comorbidities and inclusion in certain racial or      in the subject’s defense systems or combinations
the immune system to attack the offending               ethnic populations are associated with increased      of these factors are responsible for the refractory
bacteria is generally protective, immune hyper-         prevalence of periodontitis. It is important that     nature of the disease. The adoption of new
responsiveness and hypersensitivity can be              epidemiologic studies also take into consideration    diagnostic technology to detect predominant
counterproductive, leading to the destruction           the fact that tobacco use, oral hygiene,              bacterial species followed by selective antibiotic
of healthy tissue. Nevertheless, the neutrophil/        professional prophylaxis and routine dental care      treatment may help resolve infection and disease
antibody axis is critical for full protection against   are correlated to socioeconomic status, as are        in these patients.
periodontal diseases.                                   race and ethnicity. Sex is another factor. Males
                                                        tend to have higher levels of periodontal diseases,
                                                                                                              Early-onset periodontitis
Also important is the release of certain potent                                                               The forms of periodontitis occurring in
                                                        presumably because of a history of greater
molecules called cytokines and prostaglandins,                                                                adolescents and young adults generally involve
                                                        tobacco use and differences in personal care
especially prostaglandin E2 (PGE2) which can                                                                  defects in neutrophil function. Localized juvenile
                                                        and frequency of dental visits. However, female
contribute to tissue destruction. Cytokines are                                                               periodontitis (LJP) mainly affects the first molar
                                                        hormones may play a protective role (as they do
proteins secreted by immune cells that help                                                                   and incisor teeth of teenagers and young adults,
                                                        in protecting against osteoporosis).
regulate immune responses and also affect bone,                                                               with rapid destruction of bone but almost no
epithelial and connective tissues. Most prominent       Certain systemic diseases heighten susceptibility.    telltale signs of inflammation and very little
in periodontal diseases are interleukin 1 (IL-1),       Epidemiological studies have confirmed that           supragingival plaque or calculus. Actinobacillus
tumor necrosis factor alpha (TNF-gamma) and             patients with diabetes mellitus, both type 1          actinomycetemcomitans has been isolated at 90
interferon gamma (IFN-gamma). These cytokines           and type 2, are more susceptible to periodontal       to 100 percent of diseased sites in these patients,
mediate the processes of bone resorption and            diseases. Measures such as the gingival index,        but is absent or appears in very low frequency in
connective tissue destruction.                          pocket depth and loss of attachment are more          healthy or minimally diseased sites. It is possible
                                                        severe if the diabetic patients are smokers. The      that the bacteria are transmitted among family
susceptibility and resistance                           likelihood of periodontal disease increases           members through oral contacts such as kissing or
PGE2 may play a central role in the tissue
                                                        markedly when diabetes is poorly controlled.          sharing utensils, because the same bacterial strain
destruction that occurs in periodontal diseases.
                                                        In contrast, periodontal diseases respond well        appears in affected family members. However,
Levels of PGE2 in periodontal tissue are low
                                                        to therapy and can be managed successfully            evidence of a neutrophil defect argues for a
or undetectable in health, increase in gingivitis
                                                        in patients with well-controlled diabetes. Such       genetic component. Another organism frequently
and rise significantly in periodontitis. Now there
                                                        therapy can result in improvements in the             associated with LJP is Capnocytophaga ochracea.
is increasing evidence that the level of PGE2
                                                        diabetic condition itself. There is some evidence     Neither of these bacteria dominate in the
produced in response to bacterial challenge
                                                        that osteoporosis may be a risk factor for            generalized adult form of the disease, where
(especially by endotoxin) can be used as a
                                                        periodontal disease. More clinical attachment         Porphyromonas gingivalis is considered of
measure of susceptibility.
                                                        loss and edentulousness have been reported in         greatest significance.
Presumably, the level of PGE2 production is             osteoporotic than in nonosteoporotic women.
                                                                                                              Prepubertal periodontitis is rare and can be
subject to genetic influence. Studies of identical      Two studies in 1996 showed that estrogen
                                                                                                              either general or localized. The generalized form
and fraternal twins, either reared together or          replacement therapy in postmenopausal women
                                                                                                              begins with the eruption of the primary teeth and
apart, provide evidence that genetic factors may        not only gives protection against osteoporosis,
                                                                                                              proceeds to involve the permanent teeth. There
indeed influence susceptibility or resistance           but also results in fewer teeth lost to periodontal
                                                                                                              is severe inflammation, rapid bone loss, tooth
to the common adult form of periodontitis.              disease.
                                                                                                              mobility and tooth loss. The localized form of the
Recently, a commercial test for a genetic marker
                                                        The less common rapidly progressive form of           disease is less aggressive, affecting only some
of susceptibility has been introduced. The marker
                                                        adult periodontitis typically affects people in       primary teeth. The infection involves many of the
is associated with increased production of a
                                                        their early 20s and 30s. It is characterized by       organisms associated with periodontitis, but the
particular form of interleukin 1-beta (IL-1-beta)
                                                        severe gingival inflammation and rapid loss of        mix may differ somewhat, with Actinobacillus
when stimulated by periodontopathic bacteria. In
                                                        connective tissue and bone. Many patients have        actinomycetemcomitans, Prevotella intermedia,
1996, it was found that nonsmoking adults who
                                                        an inherent defect in neutrophil response to          Eikenella corrodens and several species
are positive for the marker are 6 to 19 times more
                                                        infection. Several systemic diseases have been        of Capnocytophaga implicated. Defects in
likely to develop severe periodontitis.
                                                        associated with this form of periodontal disease,     neutrophil function noted in both forms of the
Susceptibility to adult periodontitis has also been     including type 1 diabetes, Down syndrome,             may explain why patients are highly susceptible
explored in relation to a variety of behavioral         Papillon-Lefevre syndrome, Chediak-Higashi            to other infections as well.
and demographic variables as well as to the             syndrome and HIV infection. Specific bacteria
                                                                                                              selected mucosal infections and
presence of other diseases. One of the strongest        associated with rapidly progressive disease
behavioral associations is with tobacco use. The        include Porphyromonas gingivalis, Prevotella          conditions
                                                        intermedia, Eikenella corrodens, and Wolinella        Like the skin, the mucosal lining of the mouth
risk of alveolar bone loss for heavy smokers is
                                                        recta. Most recently, mutations in the cathepsin      serves to protect the body from injury. This lining
seven times greater than for those who have not
                                                        C gene have been associated with the Papillon-        is itself subject to a variety of infections and
smoked. Cigarette smoking also may impair the
                                                        Lefevre syndrome and how the defect can result        conditions, ranging from benign canker sores to
normal host response in neutralizing infection,
                                                        in periodontal disease.                               often fatal cancers.
resulting in the destruction of healthy periodontal
tissues adjacent to the site of infection. Smokers                                                            oral candidiasis
                                                        Refractory periodontitis.
also have decreased levels of salivary and serum                                                              Chronic hyperplastic candidiasis is a red or
                                                        Refractory periodontitis is not a specific form
immunoglobulins to Prevotella intermedia and                                                                  white lesion that may be flat or slightly elevated
                                                        of disease, but refers to cases in which patients
Fusobacterium nucleatum and depressed numbers                                                                 and may adhere to soft or hard tissue surfaces,
                                                        continue to exhibit progressive disease at
of helper T cells as well. Finally, smoking alters                                                            including dental appliances. It is caused by
                                                        multiple sites despite aggressive mechanical
the cells that engulf and dispose of bacteria –                                                               species of Candida, especially Candida albicans,
                                                        therapy to remove biofilm and calculus, along
neutrophils and other phagocytes – affecting their                                                            the most common fungal pathogen isolated from
                                                        with the use of antibiotics. Refractory sites
ability to clear pathogens.                                                                                   the oral cavity. Normally, the fungi are present
                                                        exhibit elevated levels of a number of different
Epidemiologic studies have found that such                                                                    in relatively low numbers in up to 65 percent
                                                        bacteria, with the dominant species different
                                                                                                              of healthy children and adults and cause no
Page 70                                                                                                                                                Elite CME
harm. Problems arise when there is a change            young children and young adults, infection may        Recurrent aphthous ulcers or canker
in oral homeostasis – the normal balance of            take the form of primary herpetic stomatitis, with    sores
protective mechanisms and resident oral flora          symptoms of malaise, muscle aches, sore throat        Recurrent aphthous ulcers (RAU), also referred to
that maintain the health of the oral cavity, so that   and enlarged and tender lymph nodes before            as recurrent aphthous stomatitis, is the technical
defense mechanisms are compromised. Under              the appearance of the familiar cold sore blisters.    term for canker sores, the most common and
these circumstances, the fungal organisms can          These blisters usually show up on the lips, but       generally mild oral mucosal disease. Between
overgrow to cause disease. A primary disruption        any of the mucosal surfaces can be affected.          5 and 25 percent of the general population is
in homeostasis occurs with the use of antibiotics      Bright-red ulcerated areas and marked gingivitis      affected, with higher numbers in selected groups,
and corticosteroids, which can markedly change         may also be seen.                                     such as health professional students. The disease
the composition of the oral flora.                                                                           takes three clinical forms: RAU minor, RAU
                                                       Herpes viruses also cause genital infections,
Deficiencies in the immune and endocrine               which are transmitted sexually. Both HSV-1            major and herpetiform RAU. The minor form
systems are also important. Indeed, the diagnosis      and HSV-2 have been found in oral and genital         accounts for 70 to 87 percent of cases. The sores
of candidiasis in an otherwise seemingly               infections, with HSV-1 predominating in oral          are small, discrete, shallow ulcers surrounded
healthy young adult may be the first sign of HIV       areas and HSV-2 in genital areas. Herpes viruses      by a red halo appearing at the front of the mouth
infection. Other causes of candidiasis include         have also been implicated as cofactors in the         or the tongue. The ulcers, which usually last
cancer chemotherapy or radiotherapy to the head        development of oral cancers. Crowded living           up to two weeks, are painful and may make
and neck, xerostomia resulting from radiation to       conditions can result in greater contact with         eating or speaking difficult. About half of RAU
the head and neck, medications, chronic mucosal        infected individuals, which aids in transmission      patients experience recurrences every one to three
irritation, certain blood diseases and other           of HSV.                                               months; as many as 30 percent report continuous
systemic conditions. Tobacco use also has been                                                               recurrences.
                                                       Normally, the immune system mounts a
identified as a cofactor.                              successful attack on the viruses, with symptoms       RAU major accounts for 7 to 20 percent of cases
Candidiasis often causes symptoms of burning           abating by the time neutralizing antibodies appear    and usually appears as one to 10 larger coalescent
and soreness as well as sensitivity to acidic          in the bloodstream, in about 10 days. However,        ulcers at a time, which can persist for weeks or
and spicy foods. Patients may complain of a            herpes viruses are notorious for their ability to     months. Herpetiform RAU has been reported
foul taste in the mouth. However, it can also be       avoid immune detection by taking refuge in the        as occurring in 7 to 10 percent of RAU cases.
asymptomatic. Genomic analysis of the Candida          nervous system, where they can remain latent          The ulcers appear in crops of 10 to 100 at a
albicans genome is helping investigators identify      for years. In oral herpes, the virus commonly         time, concentrating in the back of the mouth and
numerous genes that code for virulence factors,        migrates to the nearby trigeminal ganglion, the       lasting for seven to 14 days.
including enzymes that can facilitate adhesion         cluster of nerve cells whose fibers branch out to     RAU can begin in childhood, but the peak period
to and penetration of mucous membranes. At the         the face and mouth. In about 20 to 40 percent         for onset is the second decade. About 50 percent
same time, researchers are exploring novel gene        of people who are virus-positive, the virus may       of close relatives of patients with RAU also have
technologies to increase production of a family        reactivate, with infectious virus particles moving    the condition, and a high correlation of RAU has
of native salivary proteins, the histatins that        to the oral cavity to cause recurrent disease.        been noted in identical but not fraternal twins.
have known anticandidal and other antimicrobial        The usual site of a recurrent lesion is on or near    Associations have been found between RAU and
effects.                                               the lips. Recurrences are rarely severe, and          specific genetic markers.
The most common form of oral candidiasis is            lesions heal in seven to 10 days without scarring.
denture stomatitis. It occurs when tissues are         The recurrences may be provoked by a wide
traumatized by continued wearing of ill-fitting        range of stimuli, including sunlight, mechanical
or inadequately cleaned dental appliances and is       trauma and mild fevers such as occur with a cold.
described as chronic erythematous candidiasis.         Emotional factors may play a role as well.
Another form, candidal angular cheilosis, occurs
                                                       oral human papillomavirus infections
in the folds at the angles of the mouth and is
                                                       There are more than 100 recognized strains of
closely associated with denture sore mouth.
                                                       oral human papillomavirus (HPV), a member of
Other common forms of Candida infection are                                                                  This picture shows a canker sore in the mouth
                                                       the papovavirus family, implicated in a variety
pseudomembranous candidiasis (thrush), which                                                                                on the upper lip.
                                                       of oral lesions. Most common are papillomas
may affect any of the mucosal surfaces, and acute
                                                       (warts) found on or around the lips and in the
erythematous candidiasis, a red and markedly                                                                 RAU has also been associated with
                                                       mouth. HPV is found in 80 percent of these oral
painful variant commonly seen in AIDS patients.                                                              hypersensitivities to some foods, food dyes and
                                                       squamous papillomas. The virus has also been
                                                                                                             food preservatives. Nutritional deficiencies –
In most cases, Candida infection can be                identified in 30 to 40 percent of oral squamous
                                                                                                             especially in iron, folic acid, various B vitamins
controlled with antifungal medications used            cell carcinomas and has been implicated in
                                                                                                             or combinations thereof – have also been
locally or systemically. Control is difficult,         cervical cancer as well. Whether a cancer or
                                                                                                             reported, and improvements noted with suitable
however, in patients with immune dysfunction,          nonmalignant wart develops may depend on
                                                                                                             dietary supplements.
as in AIDS, or other chronic debilitating diseases.    which virus is present or on which viral genes are
Often the organisms become resistant to standard       activated.                                            The two factors that have been found to have the
therapy, and aggressive approaches are necessary.                                                            strongest association with RAU are immunologic
                                                       Oral warts are most often found in children,
The spread of oral candidiasis to the esophagus                                                              abnormality, possibly involving autoimmunity
                                                       probably as a result of chewing warts on the
or lungs can be life-threatening and is one of the                                                           and trauma.
                                                       hands. In adults, sexual transmission from the
criteria used to define frank AIDS.
                                                       anogenital region can occur.                          Volunteers with and without a history of RAU
Herpes simplex virus infections                                                                              were studied for their reaction to the trauma of a
                                                       In general, viral warts spontaneously regress after
In any given year, about a half-million Americans                                                            needle prick to the inner cheek tissue. No ulcers
                                                       one or two years. The immune system normally
will experience their first encounter with the                                                               developed in non-RAU subjects, but nearly half
                                                       keeps HPV infections under control, as evidenced
herpes simplex virus type 1 (HSV-1), the cause                                                               of those prone to canker sores had a recurrence.
                                                       by the increased prevalence of HPV-associated
of cold sores. That first encounter usually occurs     lesions in HIV-infected patients and others with      RAU also can occur in a number of systemic
in the oral region and may be so mild as to go         immunodeficiency.                                     diseases, including HIV infection, ulcerative
unnoticed. But in some people, particularly                                                                  colitis, Crohn’s disease and Behçet’s disease. In
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general, people who are immunocompromised               number of teratogens (environmental agents that      facial deformities exacerbate the psychological
are more susceptible to RAU, as are people with         can cause birth defects) have been implicated,       difficulties these youngsters face.
a variety of blood diseases.                            as well as defects in essential nutrients such
                                                                                                             Investigators have identified the gene involved
                                                        as folic acid. Smoking by the mother during
RAU itself does not give rise to other illnesses                                                             in an autosomal dominant form of the syndrome.
                                                        pregnancy also increases the risk. It is becoming
but is uncomfortable. Symptomatic treatment                                                                  The function of the gene is not yet known, but its
                                                        increasingly evident that most diseases and
includes topical analgesics, antibacterial rinses,                                                           identity will provide opportunities for prenatal
                                                        disorders, not just craniofacial anomalies, result
topical corticosteroids and a new prescription                                                               diagnosis, gene therapy and further understanding
                                                        from interactions involving multiple genes and
medication that reduces pain and healing time.                                                               of craniofacial development.
                                                        environmental factors.
Developmental disorders                                 Infants with clefts have difficulty with vital
                                                                                                             The Pierre Robin syndrome
The importance of the face as the bearer of                                                                  Deficient development of the first-branchial-
                                                        oral functions such as feeding, breathing,
identity, character, intelligence and beauty is                                                              arch-derived mandibular portion results in the
                                                        speaking and swallowing. They are also
universal. Craniofacial birth defects, which can                                                             lower jaw being set far back in relation to the
                                                        susceptible to repeated respiratory infections.
include such manifestations as cleft lip or palate,                                                          forehead. As a result, the tongue is set back and
                                                        As these children grow, they must cope with
eyes too closely or widely spaced, deformed ears,                                                            may obstruct the posterior airway, compromising
                                                        the social consequences of a facial deformity,
eyes mismatched in color and facial asymmetries,                                                             respiration and, in severe cases, leading to
                                                        delayed and altered speech, frequent illness and
can be devastating to the parents and child                                                                  inadequate aeration and failure to thrive. The
                                                        repeated surgeries that may persist through late
affected. Surgery, dental care, psychological                                                                infant is also at risk for the development of cor
counseling and rehabilitation may help to                                                                    pulmonale, an enlargement of the right ventricle
ameliorate the problems but often at great cost         Current molecular epidemiology investigations        of the heart that occurs secondarily to a chronic
and over many years.                                    have examined both syndromic and                     lung condition. Cleft palate may be another
                                                        nonsyndromic (isolated) cleft lip/palate and cleft   consequence.
Although each developmental craniofacial
                                                        palate. Linkage studies have identified a number
disease or syndrome is relatively rare, the                                                                  The Digeorge/velocardiofacial syndrome
                                                        of candidate genes, including MSX1, RAR, an
number of children affected worldwide is in                                                                  The primary defect in the DiGeorge syndrome
                                                        X-linked locus and the genes for TGF-beta-3 and
the millions. In addition, craniofacial defects                                                              results from altered development of the
                                                        TGF-alpha. The pattern of inheritance in cleft
form a substantial component of many other                                                                   fourth branchial arch and the third and fourth
                                                        lip/palate and cleft palate suggests that between
developmental birth defects, largely because they                                                            pharyngeal pouches. Deficiencies affecting the
                                                        two and 20 genes may be involved, with one
occur very early in gestation, when many of the                                                              thymus, parathyroid glands and the great vessels
                                                        gene representing a major component in the
same genes that orchestrate the development of                                                               that derive from these structures result. The facial
                                                        development of the cleft. One of the common
the brain, head, face and mouth are also directing                                                           features are subtle and include a squared-off
                                                        syndromic forms of cleft lip/palate, the Van der
the development of the limbs and many vital                                                                  nasal tip, small mouth and widely spaced eyes.
                                                        Woude syndrome, is caused by an autosomal
internal organs, such as the heart, lungs and liver.                                                         Similar facial features, along with heart defects,
                                                        dominant form of inheritance at a locus on
By about the third week after fertilization, the        chromosome 1. Future molecular genetic studies       are seen in the velocardiofacial syndrome. Both
three germ layers of the embryo – the ectoderm,         will be needed to provide the information            syndromes are associated with deletions on the
endoderm and mesoderm – have formed, as well            necessary for prenatal diagnosis, calculation of     long arm of chromosome 22 (22q11). Further
as the first of four sets of paired swellings – the     risk and potential gene therapy.                     characterization of this chromosomal deletion
branchial arches – that appear at the sides of                                                               region will provide information on the specific
                                                        The Treacher Collins syndrome –                      gene(s) affected and its function in craniofacial
the head end of the embryo. Some craniofacial
defects result from failure of the arches to            mandibulofacial dysostosis                           development.
complete their morphogenetic development.               Children with the Treacher Collins syndrome
                                                                                                             The thymus defects severely compromise cellular
Others are the result of the abnormal                   have downward-sloping eyelids; depressed
                                                                                                             immunity, depriving the body of thymus-derived
differentiation of cells derived from the ectoderm      cheekbones; a large fishlike mouth; deformed
                                                                                                             T cells and paving the way for severe infectious
and endoderm or from ectomesenchyme cells,              ears with conductive deafness; a small, receding
                                                                                                             disease. Inadequate or missing parathyroid
which originate in a part of the ectoderm (the          chin and lower jaw; a highly arched or cleft
                                                                                                             glands cause severe hypocalcemia (low blood
neural crest), in interaction with future connective    palate; and severe dental malocclusion. These
                                                                                                             calcium levels) and seizures. The great vessel
tissue (the mesenchyme).                                defects result from defective cranial neural crest
                                                                                                             abnormalities alter cardiac output and lead to
                                                        cell differentiation, migration and proliferation.
                                                                                                             compromised circulation to heart tissues.
Craniofacial anomalies caused by altered                Consequently, the first branchial arch structures
branchial arch morphogenesis                            are deficient, and all derivative craniofacial       Cranial bone and dental anomalies
Cleft lip/palate and cleft palate                       components are affected.                             Defects in the timing of developmental events
The most common of all craniofacial anomalies                                                                can cause premature fusion of cranial bones.
and among the most common of all birth defects,                                                              Impairments of tooth development can result
are clefts of the lip with or without cleft palate                                                           from interruptions of the developmental sequence
and cleft palate alone; these occur at a rate of 1 to                                                        at several different stages.
2 out of 1,000 births, resulting in more than 8,000
affected newborns every year. Cleft lip/palate and
cleft palate are distinct conditions with different
patterns of inheritance and embryological origins.
The male to female ratio of cleft lip/palate is 2
to 1; the ratio for cleft palate alone is just the      Treacher Collins syndrome patients have a jaw
reverse, 1 to 2.                                                          deformity.

These anomalies result from the failure of              The underdeveloped facial structures can
the first branchial arches to complete fusion           contribute to airway blockage and repeated
processes. Clefting can occur independently or as       upper respiratory infections, either of which
part of a larger syndrome that may include mental       can be fatal. The faulty development of the           This child has a facial deformity caused by a
retardation and defects of the heart and other          ears leads to a conductive deafness. The severe                      cleft lip/palate.
organs. Not all cases of clefting are inherited; a
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Craniosynostoses                                       recessive dystrophic type – manifests as blisters      determined but appears to be essential for bone
Some craniofacial anomalies are associated with        or bullae that appear shortly after birth on skin      development.
so-called master genes that orchestrate a program      areas following minor trauma. Mutations in
by which the embryo assumes its basic shape.           keratin genes that contribute to the epithelial        injury
                                                       cell cytoskeleton have been correlated with this       The common perception is that injuries are
Craniosynostosis, which occurs in approximately
                                                       condition.                                             random occurrences that are unpredictable and
1 out of 3,000 births, is one such anomaly. It
                                                                                                              hence unpreventable. In actuality, experts in
results in the premature fusion of the cranial         The oral manifestations include both mucosal           the field make the point that there are no basic
sutures, a dangerous condition that puts pressure      bullae and altered teeth. Altered teeth with           scientific distinctions between injury and disease.
on the developing brain. A number of diseases          hypoplastic enamel develop and exhibit an              Injuries have been categorized as “intentional”
and syndromes, including Crouzon’s, Apert’s            increased susceptibility to caries. Oral bullae        and “unintentional.” People identified as being
Boston-type craniosynostosis, Pfeiffer’s and           develop from even the slightest mucosal trauma.        at risk for certain injuries, as well as the causes
Saethre-Chotzen, share this anomaly, but differ        The condition is painful and dangerous because         of those injuries, can be targeted for appropriate
in other features, which can include structural        of the constant risk that the bullae will become       prevention strategies. Such an approach is
defects such as webbing of the hands and feet          infected.                                              broadly applicable to sports, falls and motor
as well as mental retardation. Boston-type
                                                       Craniofacial manifestations of single-gene             vehicle injuries (unintentional) as well as to
craniosynostosis has been linked to MSX2, one of
                                                                                                              injuries caused by abusive and violent behaviors
the master genes. Several of the other syndromes       defects
involve point mutations at one or another locus        In many craniofacial defects, mutations within a
in genes that code for fibroblast growth factor        single gene manifest as complex syndromes with         Injuries are a major public health problem,
receptors (FGFR 1, 2 and 3). Collectively, these       varied organ and limb defects as well as facial        outranking cancer and heart disease as a leading
genes are associated with cell regulation, either      anomalies.                                             cause of death in some age groups of the
through mediating growth factor effects or by                                                                 population. Cranial injuries in particular are a
serving as transcription factors.                      Ectodermal dysplasias                                  leading cause of mortality. Oral-facial injuries
                                                       The ectodermal dysplasias (EDs) are a family           can bring disfigurement and dysfunction, greatly
Hereditary hypodontia or anodontia                     of hereditary diseases first observed by Charles       diminishing the quality of life and contributing to
Conditions of underdeveloped teeth (hypodontia)        Darwin over a century ago. They involve defects        social and economic burdens.
or their complete absence (anodontia) have been        in two or more tissues derived from the ectoderm
correlated with specific genes, such as MSX1 and       – skin, hair, teeth, nails and sweat glands.           The leading causes of oral and craniofacial
LEF1. The complete absence of teeth alters the         The ectodermal structures fail to differentiate        injuries are sports, violence, falls and motor
bony development of the mandible and maxilla.          properly owing to altered epithelial-mesenchymal       vehicle collisions. Oral cavity injuries may also
                                                       signaling. A gene, EDA, at an X-linked locus           be caused by foreign objects in food.
Amelogenesis imperfecta and
                                                       has been linked to the syndrome, and ongoing           sports
dentinogenesis imperfecta                              research is aimed at determining the function
Amelogenesis imperfecta and dentinogenesis                                                                    Craniofacial sports injuries occur not only in
                                                       of the gene and the molecular mechanism of             contact sports, but also in individual activities
imperfecta are linked to defects in structural         the syndromes. More recently, investigators
genes that code for proteins essential to the                                                                 such as bicycling, skating, and gymnastics,
                                                       have discovered genes linked to autosomal              especially on trampolines. Each sport predisposes
development of tooth enamel (amelogenesis              (e.g., non-sex-linked) forms of ED, displaying
imperfecta) or dentin (dentinogenesis                                                                         its participants to a specific array of extrinsic
                                                       both dominant and recessive inheritance. Oral          risk factors. These include physical contact,
imperfecta). The teeth are weak and extremely          manifestations of the ectodermal dysplasias are
sensitive to temperature and pressure. The                                                                    projectiles such as balls and pucks, and the
                                                       associated with the teeth. Alterations in tooth        quality of the playing field and equipment.
ordinary forces of chewing are painful and can         development can include hypodontia, anodontia
lead to further wear and pain.                                                                                In contact sports, the absence of protective
                                                       and conically shaped teeth.                            equipment such as head guards and mouth
The enamel matrix genes include tuftelin,                                                                     guards is a major risk factor. In a recent survey of
                                                       The Waardenburg syndrome
ameloblastin and amelogenin; researchers have          The Waardenburg syndrome has been subdivided           school-aged children in organized sports, football
begun to link mutations in these genes with            into several types. All involve a variety of           was the only sport in which the majority of
amelogenesis imperfecta. Similarly, genes labeled      abnormalities in the position and appearance of        participants used mouth guards and headgear.
DSP and DPP have been characterized for dentin         the nose and eyes, with pigment changes that may       There are intrinsic risk factors as well, relating to
matrix and are associated with the inheritance of      cause one eye to differ in color from the other.       characteristics of the individual participant. These
dentinogenesis imperfecta.                             Other signs include deafness, a mildly protruding      include age, sex, injury history, body size, aerobic
                                                       jaw, cleft lip and palate, and skeletal deformities.   fitness and muscle strength, central motor control
Craniofacial defects secondary to other
                                                       The syndrome is inherited in an autosomal              and general mental ability.
developmental disorders                                dominant manner with complete penetrance and
A number of genetic diseases occur in which                                                                   Falls
                                                       variable expression. Specific genes associated
craniofacial defects are secondary to a more                                                                  Falls are a major cause of trauma to teeth,
                                                       with this syndrome are members of the
generalized structural defect.                                                                                primarily to incisors. Fractures of the crowns of
                                                       homeobox family that regulate the transcription
osteogenesis imperfecta                                of other genes: Waardenburg type 1 with PAX3;          the teeth, unlike fractures of bones, do not heal or
Inherited mutations of collagen genes lead to a        Waardenburg type 2 with MITF, 3q14.1; and              repair, and affected teeth often have an uncertain
number of “brittle bone” diseases characterized        Waardenburg type 3 with PAX3, 2q35.                    prognosis. Problems may develop later due to
by defects in mineralized tissues that form from                                                              damage to the pulp.
                                                       Cleidocranial dysplasia
a collagen-rich matrix. Osteogenesis imperfecta                                                               Motor vehicle collisions
                                                       The inheritance of a regulatory gene defect in
presents a spectrum of deficiencies that includes                                                             The effects of motor vehicle collisions may range
                                                       cleidocranial dysplasia leads to features that
fragile bones, clear or blue sclera, deafness, loose                                                          from minor and reversible effects to long-term
ligaments and painful dentinogenesis imperfecta-       include delayed tooth eruption, supernumerary
                                                       teeth, altered or missing collarbones, short stature   medical, surgical and rehabilitative consequences.
like changes in the teeth.                                                                                    Post-traumatic headaches and chronic oral-facial
                                                       and possible failure of cranial suture closure.
Epidermolysis bullosa – recessive                                                                             pain can occur. Neuromuscular and glandular
                                                       The exact mechanism of the associated gene,
dystrophic type                                                                                               damage may cause short- or long-term problems
                                                       CBFA1, located on chromosome 6, has not been
The gene defect in epidermolysis bullosa –                                                                    with chewing, swallowing and tearing or result in
                                                                                                              facial tics or paralysis.
Elite CME                                                                                                                                                  Page 73
violence                                              Diagnosis is difficult in the early stages, and       successful use of antidepressants, psychotherapy
The family is the single most frequent locus of       women often report that it took many years            or both.
violence in Western society. Domestic violence        and consultations with many specialists before
                                                      they received the correct diagnosis. Diagnosis
                                                                                                            Tic douloureux
includes child abuse, spousal and elder abuse,
                                                                                                            The oral-facial region is also subject to pain
and abuse of the disabled. Child abuse is of          involves demonstration of specific antibodies
                                                                                                            that can be paroxysmal or continuous along a
particular concern to the oral health community       in the blood characteristic of an autoimmune
                                                                                                            distinct nerve distribution. The most frequently
because 65 percent of cases involve head and          disorder, a labial (minor) salivary gland biopsy,
                                                                                                            encountered of these oral facial neuralgias is tic
oral-facial trauma, and dentists are required to      and a series of eye tests to measure flow rate and
                                                                                                            douloureux, or trigeminal neuralgia, a disease
report suspected cases of child abuse. In the         tissue characteristics. Confirmatory tests include
                                                                                                            of unknown etiology affecting one, two or all
young child, head injury is the most common           an evaluation of salivary flow and chemistry.
                                                                                                            three branches of the trigeminal nerve. The pain
cause of death.
                                                      Patients with Sjögren’s syndrome are at some risk     is highly intense and of a stabbing nature, and
Psychological trauma from abuse can result            of developing diseases such as non-Hodgkin’s          lasts for a few seconds. This transient attack
in sleep disturbances, eating disorders,              lymphoma; clinical data indicate that such            may be repeated every few minutes or several
developmental growth failure in young                 lymphomas develop in 5 percent of patients with       hours. There may be no precipitating factor, or
children and nervous habits such as lip and           Sjögren’s syndrome.                                   it may occur in response to a gentle touch or
fingernail biting and thumb sucking. Effects                                                                a breeze wafting across the face – a condition
may also include chronic underachievement in          Histological examination shows that immune            experts call allodynia, the feeling of pain in
school and poor peer relationships. In abusive        cells infiltrate the glands and cluster around the    response to a normally nonpainful stimulus. On
families, physical neglect is commonplace, with       secretory elements, resulting in a breakdown          other occasions, there may be a specific trigger
inadequate provision of basic needs, including        of the normal structure of the gland. The             zone. Although spontaneous remission for weeks
medical and oral health care.                         mechanisms by which this occurs involve               or months may occur, it is rarely permanent.
                                                      immune-cell-mediated inflammation and                 Given the unknown, unpredictable nature of tic
selected chronic pain conditions                      stimulation of the salivary gland cells themselves
Oral, dental or craniofacial signs and symptoms                                                             douloureux, it is not surprising that fear of pain
                                                      to produce tissue-destructive molecules such          comes to dominate these patients’ lives, as they
play a critical role in autoimmune disorders
                                                      as cytokines. Another hypothesis is that a viral      avoid doing anything that might trigger an attack.
such as Sjögren’s syndrome and in a number of
                                                      infection of the glands may trigger the immune
chronic and disabling pain conditions.                                                                      Trigeminal neuralgia generally occurs in later
                                                      response that leads to autoimmunity, whereas
sjögren’s syndrome                                    genetic or regulatory alterations might lead to       life, but also occurs in younger individuals
Sjögren’s syndrome is one of several autoimmune       abnormalities in apoptosis.                           affected by multiple sclerosis, where it is
disorders in which the body’s own cells and                                                                 assumed to be associated with lesions (multiple
                                                      In addition to saliva substitutes and artificial      sclerosis “plaques”) in the brain stem. Medical
tissues are mistakenly targeted for destruction
                                                      tears, some medications, such as pilocarpine and      treatment depends largely on the use of a
by the immune system. Like other autoimmune
                                                      cevimeline, are prescribed to increase salivary       drug that has become a virtual specific, the
conditions, Sjögren’s syndrome is more prevalent
                                                      flow from the residual healthy gland tissue, again    antiepileptic drug carbamazepine. For those
among women. The ratio of females to males
                                                      providing symptomatic relief only. The problems       patients with no consequential adverse effects, it
affected is 9 to 1, with symptoms usually
                                                      that develop in the other organ systems are also      can control the disease. An alternative for chronic
developing in middle age. There are an estimated
                                                      treated symptomatically. At advanced stages,          sufferers is the surgical removal of a small vein or
1 million to 2 million individuals in the United
                                                      steroids are employed intermittently to alleviate     artery that may be exerting pressure on the nerve
States with Sjögren’s syndrome.
                                                      problems.                                             root or the selective destruction of the nerve
The disease occurs in two forms. Primary                                                                    fibers themselves using chemical or electrical
Sjögren’s involves the salivary and lacrimal (tear)   Acute and chronic oral-facial pain
                                                                                                            methods. In many cases, these procedures can
glands. In secondary Sjögren’s the glandular          Since the 19th century when two dentists, Horace
                                                                                                            produce complete relief from pain.
involvement is accompanied by the development         Wells and Frederick Morton, demonstrated the
of a connective tissue or collagen disease, most      analgesic powers of nitrous oxide and ether, oral     Temporomandibular disorders
often rheumatoid arthritis, lupus erythematosis,      health investigators have been recognized leaders     Various etiological factors, including trauma,
scleroderma or biliary cirrhosis.                     in the field of pain management worldwide. Their      can give rise to pain and dysfunction in the
                                                      analyses of the cells, pathways and molecules         temporomandibular joint and surrounding
The glandular involvement causes a marked             involved in the transmission and modulation           muscles, conditions collectively called
reduction in fluid secretion, resulting in            of pain have given rise to a growing variety          temporomandibular disorders (TMDs). The pain
xerostomia and xerophthalmia (dry eyes).              of medications, often combined with other             may be localized or radiate to the teeth, head,
The constant oral dryness causes difficulty in        approaches, that can control acute and chronic        ears, neck, and shoulders. Abnormal grating,
speaking, chewing and swallowing; the dry eyes        pain. Pain researchers today stress that chronic      clicking or crackling sounds, known as crepitus,
often itch and feel gritty. There is no cure for      pain can become a disease in itself, causing long-    in the joint often accompany localized pain. Pain
Sjögren’s, and patients often carry eyedrops and      term detrimental changes in the nervous system.       is also found in response to clinical palpation
water bottles or saliva substitutes in an attempt     These changes may affect resistance to other          of the affected structures. TMDs are common,
to provide symptomatic relief. Clinically, the        diseases as well as effectively destroy quality of    occurring in as many as 10 million Americans.
reduction in salivary flow changes the bacterial      life. Most people have experienced acute pain         Although surveys indicate that both sexes are
flora, which, in addition to the reduction in         involving teeth and the oral tissues at one time or   affected, the majority of individuals seeking
salivary protective components, increases the         another.                                              treatment are women of childbearing age, a
risk of caries and candidiasis. Recent studies
                                                                                                            phenomenon suggesting that hormonal influences
have indicated that there is a reduction in           Atypical facial pain
                                                                                                            should be investigated.
masticatory function and an increased prevalence      Atypical facial pain is characterized by a
of periodontal disease. In advanced stages, the       continuous dull ache on one or both sides, most       Several factors can contribute to the onset or
salivary glands may swell because of obstruction      frequently in the region of the maxilla (the          exacerbation of TMD symptoms. These factors
and infection or lymphatic infiltration. In           upper jaw). The pain tends to be episodic and is      include:
both forms of the disease, other systems may          aggravated by fatigue, worry or emotional upset.       Certain developmental anomalies.
eventually become affected. Nasal, laryngeal          It is often accompanied by pain elsewhere in           Injury to the jaw from accidents or abuse.
and vaginal dryness may occur, as well as             the body and depression. Once a dental cause           Oral habits that greatly stress the joint
abnormalities in internal organs.                     can be ruled out, pain resolution depends on the
Page 74                                                                                                                                              Elite CME
    and musculature, such as tooth grinding           infection and disorder highlights                     large overlap in the clinical appearance of oral
    (bruxism).                                           Microbial infections, including those caused      manifestations of various diseases with different
   Jaw manifestations of systemic diseases such          by bacteria, viruses and fungi, are the primary   etiologies, and the clinical diagnosis often
    as fibromyalgia and arthritic diseases; and           cause of the most prevalent oral diseases.        involves ancillary procedures, which may include
    some irreversible treatments for initial signs        Examples include dental caries, periodontal       laboratory tests, diagnostic imaging and biopsy.
    and symptoms.                                         diseases, herpes labialis and candidiasis.        Oral tissues may also reflect immune deficiency.
The multiplicity of factors that may cause or            The etiology and pathogenesis of diseases         For example, nearly all HIV-infected individuals
contribute to TMDs has unfortunately led to               and disorders affecting the craniofacial          develop oral lesions at some time during their
a multiplicity of treatments. Most of these               structures are multifactorial and complex,        illness. Other immunosuppressed individuals may
treatments have not been tested in randomized             involving an interplay among genetic,             have the same lesions. However, the presentation
controlled clinical trials. During the 1970s and          environmental and behavioral factors.             and the extent, severity and management of
1980s, many individuals underwent surgery that           Many inherited and congenital conditions          some of these lesions may reflect nuances due to
proved unsuccessful in many cases.                        affect the craniofacial complex, often            variation in the underlying systemic condition.
                                                          resulting in disfigurement and impairments        For example, the linear gingival erythema and
Leading investigators have proposed standardized          that may involve many body organs and             necrotizing ulcerative periodontitis sometimes
research diagnostic criteria to clarify the kinds         systems and affect millions of children           seen in HIV infection have been difficult
of pathology that can give rise to TMDs and to            worldwide.                                        to resolve with routine dental curettage and
classify the most common forms of TMDs. Such             Tobacco use, excessive alcohol use and            prophylaxis.
criteria could be used in designing clinical trials       inappropriate dietary practices contribute to
and could ultimately lead to better diagnostics,          many diseases and disorders. In particular,       The appearance of soft or hard tissue
treatments and prevention.                                tobacco use is a risk factor for oral cavity      pigmentation is associated with a number of
                                                          and pharyngeal cancers, periodontal diseases,     diseases and treatments. Malignant melanoma
The criteria use two dimensions or axes:
                                                          candidiasis and dental caries, among other        can appear in the mouth as brown or black flat or
 Axis I delineates various forms of joint or
                                                          diseases.                                         raised spots. Kaposi’s sarcoma can appear as a
   muscle pathology.
                                                         Some chronic diseases, such as Sjögren’s          flat or raised pigmented lesion. Addison’s disease
 Axis II explores pain-related disability and
                                                          syndrome, present with primary oral               causes blotches or spots of bluish-black or dark
   psychological status.
                                                          symptoms.                                         brown pigmentation to occur early in the disease.
The approach requires detailed clinical                  Oral-facial pain conditions are common and        Congenital discrete brown or black patches (nevi)
examinations and patient histories.                       often have complex etiologies.                    can appear in any part of the mouth. Pigmentation
                                                                                                            of the tooth crowns may be seen in children with
A mirror, a model and a better                        The range of oral, dental and craniofacial diseases   cystic fibrosis and porphyria and those exposed to
understanding of diseases and disorders               and conditions that take a toll on the U.S.           tetracycline during tooth development.
Studying the diseases and disorders that affect       population is extensive. This course provides
craniofacial tissues can provide scientists with      highlights of diseases and conditions affecting       The oral tissues can also reflect nutritional status
models of systemic pathology. Because some            Americans using available national and state data     and exposure to risk factors such as tobacco. The
craniofacial tissues, such as bones, mucosa,          to describe the burden of disease in the United       tongue appears smooth in pernicious anemia.
muscles, joints and nerve endings, have               States. There is no single measure of oral health     Group B vitamin deficiency is associated with
counterparts in other parts of the body and these     or the burden of oral diseases and conditions, just   oral mucositis and ulcers, glossitis, and burning
tissues are often more accessible to research         as there is no single measure of overall health or    sensations of the tongue. Scurvy, caused by
analysis than deeper-lying tissues, researchers       overall disease. The relationship of oral health to   severe vitamin C deficiency, is associated with
studying craniofacial tissues can gain valuable       the use of dental services is described.              gingival swelling, bleeding, ulceration and
insights into how cancer develops, the role of                                                              tooth loosening. Lack of vitamin D in utero or
                                                      However, the effects of health care visits and of     infancy impairs tooth development. Enamel
inflammation in infection and pain, the effects of    specific services rendered need further study.
diet and smoking, the consequences of depressed                                                             hypoplasia may result from high levels of
immunity and the changes that can arise from a        Physical signs and symptoms of disease                fluoride or from disturbances in calcium and
mutated gene.                                         and risk factors                                      phosphate metabolism, which can occur in
                                                      A number of signs and symptoms of disease,            hypoparathyroidism, gastroenteritis, and celiac
Other craniofacial tissues, teeth, gingiva, tongue,                                                         disease. The mouth also can reflect the effects of
                                                      lifestyle behaviors and exposure to toxins
salivary glands and the organs of taste and                                                                 tobacco use, perhaps providing the only visible
                                                      can be detected in or around the craniofacial
smell, are unique to the craniofacial complex.                                                              evidence of its adverse effects.
                                                      complex. Pathogens entering the mouth may
Study of the diseases affecting these tissues
                                                      proliferate locally with oral and pharyngeal          oral manifestations of Hiv infection and
has revealed a wealth of information about
                                                      signs and symptoms; other pathogens may enter         of osteoporosis
their special nature as well as the molecules
                                                      the bloodstream directly or through lymphatic         The mouth can serve as an early warning system,
and mechanisms that normally operate for the
                                                      channels and cause generalized disease. Oral          diagnostic of systemic infectious disease and
protection, maintenance and repair of all the oral,
                                                      signs suspected to be indications of systemic         predictive of its progression, such as with HIV
dental and craniofacial tissues. When factors
                                                      illness may be confirmed by the presence of rash,     infection. In the case where oral cells and tissues
perturb these nurturing elements, the oral health
                                                      fever, headache, malaise, enlarged lymph nodes        have counterparts in other parts of the body, oral
scale can tip toward disease. When those factors
                                                      or lesions elsewhere on the body.                     changes may indicate a common pathological
stem from systemic diseases or disorders, the
mouth can sometimes mirror the body’s ill health.     Swollen parotid glands are a cardinal sign            process. During routine oral examinations and
Similarly underscoring the connection between         of infection with the mumps virus and can             perhaps in future screening tests, radiographic or
oral and general health are studies suggesting        also be seen in individuals with Sjögren’s            magnetic resonance imaging of oral bone may be
that poor dental health, mainly due to chronic        syndrome and HIV. The salivary glands are             diagnostic of early osteoporotic changes in the
dental infections, may heighten the risk for both     also frequently involved in tuberculosis and          skeleton. The following sections provide details.
cardiovascular disease and stroke independently       histoplasmosis infections. Oral signs of infectious
                                                                                                            Hiv infection
of factors such as social class and established       mononucleosis, caused by Epstein-Barr virus,
                                                                                                            The progressive destruction of the body’s
cardiovascular risk factors.                          include sore throat, gingival bleeding and
                                                                                                            immune system by HIV leads to a number of
                                                      multiple pinpoint-sized hemorrhagic spots
                                                                                                            oral lesions, such as oral candidiasis and oral
                                                      (pettechiae) on the oral mucosa. There can be a
Elite CME                                                                                                                                                Page 75
hairy leukoplakia, that have been used not only       these instances the saliva/plasma concentration         saliva as a result of chemotherapy, radiation and
in diagnosis but also in determining specific         ratio must be determined experimentally. Most           medications causing hyposalivation, allows a
stages of HIV infection. Oral candidiasis is rarely   recently, oral fluids have been used as a source of     portal of entry for invading pathogens.
seen in previously healthy young adults who           microbial or host DNA.
have not received prior medical therapy such
                                                                                                              oral infections and bacteremia
                                                      Saliva has the potential of replacing blood, the        Oral microorganisms and cytotoxic byproducts
as cancer chemotherapy or treatment with other
                                                      current standard for testing many diseases and          associated with local infections can enter the
immunosuppressive drugs. It was associated
                                                      conditions (e.g., diabetes, infectious disease,         bloodstream or lymphatic system and cause
with AIDS as early as 1981 in the first report
                                                      Parkinson’s disease, alcoholic cirrhosis,               damage or potentiate an inappropriate immune
of the syndrome and was frequently noted
                                                      Sjögren’s syndrome and cystic fibrosis                  response elsewhere in the body. Dissemination of
among otherwise asymptomatic HIV-positive
                                                      sarcoidosis). Important goals for the future are        oral bacteria into the bloodstream (bacteremia)
populations. Oral candidiasis may be the first
                                                      the development of new diagnostic tests for early       can occur after most invasive dental procedures,
sign of HIV infection and often occurs as part
                                                      disease detection, defining individual patient          including tooth extractions, endodontic therapy,
of the initial phase of infection, the acute HIV
                                                      risk of adverse response to drugs, monitoring           periodontal surgery and scaling and root planing.
syndrome. It tends to increase in prevalence
                                                      therapeutic progress and determining outcomes           Even routine oral hygiene procedures such as
with progression of HIV infection when CD4
                                                      of treatment. Key issues in the development of a        daily toothbrushing, subgingival irrigation and
lymphocyte counts fall. It also appears to be the
                                                      new generation of saliva diagnostics include their      flossing may cause bacteremia. However, these
most common oral manifestation in pediatric
                                                      selectivity, sensitivity, response time, dynamic        distant infections have been seen more often
HIV infection and has been shown to proceed
                                                      range (values of interest), representative sampling     in high-risk patients such as those who are
to esophageal candidiasis, a sign of overt
                                                      and, perhaps most important, their reliability or       immunocompromised.
AIDS. Both the pseudomembranous and the
                                                      stability as well as their ability to assess multiple
erythematous forms of candidiasis appear to                                                                   Oral bacteria have several mechanisms by
                                                      substances simultaneously.
be important predictors of progression of HIV                                                                 which they invade mucosal tissues, perhaps
infection.                                            For the clinician, the mouth and face provide           contributing to their ability to cause bacteremias.
                                                      ready access to physical signs and symptoms             For example, oral bacteria and their products
Like oral candidiasis, oral hairy leukoplakia
                                                      of local and generalized disease and risk factor        may invade the periodontal tissues directly.
in HIV-positive persons heralds more rapid
                                                      exposure. These signs and symptoms augment              Actinobacillus actinomycetemcomitans has been
progression to AIDS. Oral hairy leukoplakia is
                                                      other clinical features of underlying conditions.       found in gingival connective tissue in patients
an oral lesion first reported in the early days of
                                                      Comprehensive care of the patient requires              with localized juvenile periodontitis. Invasion
the AIDS epidemic. Since its discovery, hairy
                                                      knowledge of these signs and symptoms,                  of tissue by Porphyromonas gingivalis has also
leukoplakia has been found in HIV-negative
                                                      their role in the clinical spectrum of general          been described in vivo and in vitro. Although oral
persons with other forms of immunosuppression,
                                                      diseases and conditions, and their appropriate          bacteria can enter the blood through injured or
such as organ or bone marrow recipients and
                                                      management. Oral biomarkers and surrogate               ulcerated tissue, bacterial invasion of periodontal
those on long-term steroid therapy and less
                                                      measures are also being explored as means               tissues represents another possible mechanism.
frequently among immunocompetent persons.
                                                      of early diagnosis. With further development
                                                                                                              In the immunocompetent individual, bacteremia
Osteoporosis, a degenerative disease                  and refinement, oral-based diagnostics such
                                                                                                              originating from the oral cavity is usually
characterized by the loss of bone mineral and         as salivary tests can become widely used and
                                                                                                              transient and harmless. However, if the
associated structural changes, has long been          acceptable tools for individuals, health care
                                                                                                              individual’s immune system is compromised,
suspected as a risk factor for oral bone loss.        professionals, researchers and community
                                                                                                              the normally harmless oral bacteria may pose
In addition, measures of oral bone loss have          programs. The continued refinement of imaging
                                                                                                              a significant risk. The morbidity and mortality
been proposed as potential screening tests for        techniques also has the potential of using oral
                                                                                                              associated with oral foci of infections are hard
osteoporosis. Osteoporosis affects more than          imaging to identify early signs of skeletal bone
                                                                                                              to assess. This is due to the formidable task of
20 million people in the United States, most of       degeneration.
                                                                                                              tracking the source of an infection unless the
whom are women, and results in nearly 2 million
fractures per year. The disease is more prevalent
                                                      The mouth as a portal of entry for                      responsible pathogen is indigenous to a specific
                                                      infection                                               anatomic location.
in white and Asian American women than in
black women. Oral bone loss has been reported to      More than 500 bacterial strains have been               Viridans group streptococci (VGS) have a
be more prevalent in women than in men.               identified in dental biofilm, and more than 150         low degree of virulence but can be associated
                                                      bacterial strains have been isolated from dental        with morbidity and mortality under certain
Oral-fluid-based diagnostics: The example             pulp infections. More recently, 37 unique and           circumstances. Increased pathogenicity of
of saliva                                             previously unknown strains of bacteria were             Streptococcus viridans is most prominent in
The diagnostic value of salivary secretions           identified in dental plaque (biofilm). Most oral        individuals with neutropenia (low blood counts of
to detect systemic diseases has long been             lesions are opportunistic infections – that is,         circulating white blood cells called neutrophils)
recognized, and oral fluids and tissues (buccal       they are caused by microorganisms commonly              and has been associated with a toxic-shock-like
cells) are increasingly being used to diagnose a      found in the mouth, but normally kept in check          syndrome (TSLS) or viridans streptococcal
wide range of conditions. Saliva- and oral-based      by the body’s defense mechanisms. These                 shock syndrome (VSSS), as well as with adult
diagnostics use readily available samples and         microorganisms can induce extensive localized           respiratory distress syndrome (ARDS).
do not require invasive procedures. Researchers       infections that compromise general well-being in
have detected antibodies in saliva that are           and of themselves.                                      Although a high degree of morbidity is associated
directed against viral pathogens such as human                                                                with viridans streptococcal bacteremia, a low
                                                      However, they also may spread to other parts of         incidence of mortality has been reported.
immunodeficiency virus and hepatitis A virus or
                                                      the body if normal barriers are breached. The           Several studies have shown that under adverse
B virus. Saliva is being used to detect antibodies,
                                                      oral mucosa is one such barrier that provides           circumstances, oral flora and oral infections are
drugs, hormones, and environmental toxins. The
                                                      critical defense against pathogens and other            associated with increased incidence of morbidity.
simplest tests are those that detect the presence
                                                      challenges. Salivary secretions are a second            Reduction of oral foci of infection decreases
or absence of a substance in the saliva, such
                                                      major line of defense. Damage to the oral               systemic complications, specifically in severely
as various drugs. Greater technical challenges
                                                      mucosa from mechanical trauma, infection or             neutropenic patients undergoing chemotherapy.
are presented for tests that will be used for
                                                      salivary dysfunction with resulting derangements        In addition, hospital stays for patients with oral
therapeutic monitoring since accurate levels of
                                                      in lubricatory and antimicrobial functions of
a substance and/or its metabolites are needed. In

Page 76                                                                                                                                                Elite CME
mucositis undergoing autologous bone marrow            In addition, gram-negative pathogens including          of transforming growth factor beta (TGF-B) in
transplants were longer than for those without         P. aeruginosa, Neisseria spp. and Escherichia coli      the hamster model of oral mucositis significantly
oral mucositis.                                        remain of concern.                                      reduced basal cell proliferation and reduced
                                                                                                               the severity of mucositis associated with
Other cohorts identified at increased risk for         Cancer patients undergoing bone marrow
                                                                                                               5-fluorouracil treatment.
systemic complications due to oral bacteria            radiation who have chronic periodontal disease
include hospitalized patients unable to perform        may also develop acute periodontal infections           Other growth factors considered for use in
adequate oral hygiene, those receiving saliva-         with systemic complications. The extensive              reducing mucositis include granulocyte-
reducing medications and those taking antibiotics      ulceration of gingival sulcular epithelium              monocyte colony-stimulating factor and
that alter the oral flora. A positive dental plaque    associated with periodontal disease is not directly     granulocyte colony-stimulating factor. Bone
culture for aerobic pathogens was significantly        observable clinically, yet may represent a source       morphogenetic proteins are also in development
associated with the development of hospital-           for disseminated infection by an extensive array        for alleviating the toxicity and mucositis that
acquired pneumonia and bacteremia in a study of        of organisms. Inflammatory signs may be masked          follow chemotherapy and radiation therapy. Other
individuals in an intensive care unit.                 due to the underlying bone marrow suppression.          approaches to reducing mucositis and adverse
                                                                                                               oral effects of chemotherapy and radiation
In addition, several case reports have been            Viruses are also associated with clinically
                                                                                                               therapy include fractionating the dose of radiation
published implicating indigenous oral flora in         important oral disease in patients receiving
                                                                                                               and combining chemotherapy with growth factors
the development of brain abscesses. This serious       chemotherapy. Infections caused by herpes
                                                                                                               or with less toxic oncostatic agents.
condition is associated with a mortality rate of       simplex virus, varicella-zoster virus and Epstein-
almost 20 percent, and full recovery in only           Barr virus typically result from reactivation of a      Although the oral mucositis occurring in
slightly more than 50 percent of all patients.         latent virus, whereas cytomegalovirus infections        chemotherapy and in head and neck radiation
These data are based on single case reports and        can result via reactivation of a latent virus or        patients shares many characteristics, distinct
most probably represent rare events. However,          a newly acquired virus. The severity of the             differences also exist. For example, in contrast
they provide additional examples that point to the     infection, including fatal outcome, depends on          to chemotherapy-associated lesions, radiation
potential pathogenicity of the normal oral flora       the degree of immunocompromise.                         damage is anatomically site-specific; toxicity is
during special adverse circumstances.                                                                          localized to irradiated tissue volumes. The degree
                                                       Radiation therapy                                       of damage depends on treatment-regimen-related
oral infections as a result of therapy                 Radiation therapy disrupts cell division in healthy
                                                                                                               factors, including the type of radiation used, the
Chemotherapy                                           tissue as well as in tumors and also affects the
                                                                                                               total dose administered, the fractionation, and
Oral mucositis can be a major dose-limiting            normal structure and function of craniofacial
                                                                                                               field size. Thus, research involving both cohorts
problem during chemotherapy with some                  tissues, including the oral mucosa, salivary
                                                                                                               of cancer patients remains essential to enhancing
anticancer drugs, such as 5-fluorouracil,              glands and bone. Oral-facial complications are
                                                                                                               patient management.
methotrexate, and doxorubicin. It is estimated         common after radiation therapy to the head
that approximately 400,000 patients undergoing         and neck. The most frequent, and often the              Development of new technologies to prevent
cancer therapy each year will develop oral             most distressing, complication is mucositis, but        cancer-therapy-induced oral mucositis could
complications (NIH 1990). Infection of                 adverse reactions can affect all oral-facial tissues.   substantially reduce the risk for oral and
ulcerated mucous membranes often occurs                                                                        systemic infections, oral pain and the number
                                                       Radiation can cause irreversible damage to the
after chemotherapy, especially since patients                                                                  of hospital days. Improvement in quality of life
                                                       salivary glands, resulting in dramatic increases
are usually immunocompromised. Bacterial,                                                                      and reduction in health costs are also likely and
                                                       in dental caries. Oral mucosal alterations may
fungal and viral causes of mucositis have been                                                                 desirable outcomes.
                                                       become portals for invasion by pathogens, which
identified.                                            may be life-threatening to immunosuppressed             The new technologies could also provide a setting
The mechanism by which cancer-chemotherapy-            or bone-marrow-suppressed patients. A less              in which novel classes of chemotherapeutic
induced mucositis occurs is likely associated with     common but very serious adverse consequence is          drugs, used at increased doses, could be
the rapid rate of turnover of oral epithelial cells.   destruction of bone cells and bone death, called        implemented. These advances in turn could lead
In addition, other components likely include           osteoradionecrosis (ORN). ORN can result in             to enhanced cancer patient survival and lengthen
upregulation of pro-inflammatory cytokines             infection of the bone and soft tissue and can           the duration of disease remission.
and metabolic by-products of colonizing oral           require surgery to excise the dead tissue, which
microflora. Chemotherapy alters the integrity of       can in turn leave the face badly disfigured as
                                                                                                               A number of medications used to treat systemic
the mucosa and contributes to acute and chronic        well as functionally impaired. The likelihood
                                                                                                               diseases can cause oral complications, ranging
changes in oral tissue and physiologic processes.      of ORN is increased with trauma to the bone,
                                                                                                               from xerostomic effects to alterations in the
The ulcerated mucosa is susceptible to infection       including that caused by tooth extraction. The
                                                                                                               surface structure of the enamel or mucosa. More
by microbial flora that normally inhabit the oral      risk is especially marked when the trauma
                                                                                                               than 400 over-the-counter and prescription drugs
cavity, as well as by exogenous organisms, and         occurs near the time of radiation. Management
                                                                                                               have xerostomic side effects. These include
exacerbates the existing mucositis. Further,           includes elimination of acute or potential dental
                                                                                                               tricyclic antidepressants, antihistamines and
these microflora can disseminate systemically.         and periodontal foci of disease, increased
                                                                                                               diuretics. The dimensions and impact of these
Compromised salivary function can further              patient participation in oral hygiene, use of oral
                                                                                                               side effects vary depending on the response of the
elevate risk for systemic infection of oral origin.    topical fluorides for caries prevention and use
                                                                                                               individual patient and the duration of medication
                                                       of antiviral, antifungal or antimicrobial therapy
Both indigenous oral flora and hospital-acquired                                                               use.
                                                       for management of infections associated with
pathogens have been associated with bacteremias                                                                Staining of the teeth or mucosa is associated with
and systemic infection. Changes in infection                                                                   a variety of drugs, including tranquilizers, oral
profiles in myelosuppressed (immunosuppressed)         Combined cancer therapies                               contraceptives and antimalarials. The antibiotic
cancer patients tend to occur in cyclic fashion        Rapid developments have occurred in the                 tetracycline can cause enamel hypoplasia when
over many years. This evolving epidemiology            use of blood cell growth factors for treatment          taken by the mother during pregnancy and
is caused by multiple factors including use of         of various conditions, including the anemia             by children during tooth development. The
antibiotics. Gram-positive organisms including         of end-stage renal disease, the neutropenia             antimicrobial mouth rinse agent chlorhexidine
viridans streptococci and enterococci are              occurring with cancer care and the bone                 also can stain the teeth, but this staining
currently associated with systemic infection of        marrow toxicity and mucositis that can follow           is external and can be removed by dental
oral origin in myelosuppressed cancer patients.        aggressive chemotherapy or radiation therapy.           prophylaxis.
                                                       Researchers have found that topical application
Elite CME                                                                                                                                                  Page 77
Other drugs have been associated with gingival        include rheumatic and congenital heart disease,       have learned that many common respiratory
overgrowth, including cyclosporin, which has          complex cyanotic heart disease in children, and       infections, such as influenza, the common cold,
been used as an immunosuppressant in the              mitral valve prolapse with regurgitation. Recent      pneumonia and tuberculosis, can be transmitted
United States since 1984 to prevent rejection         studies indicate that the use of certain diet drugs   from oral secretions. Before the development of
of transplanted organs and bone marrow. This          (fenfluramine and dexfenfluramine) has induced        effective vaccines, orally transmitted diseases
drug has also been used in other countries            cardiac valvulopathy, which may in some cases         such as chickenpox, measles, mumps, polio and
for treatment of type 2 diabetes, rheumatoid          be transient. Among at-risk persons, bacteremias      diphtheria were a major source of morbidity
arthritis, psoriasis, multiple sclerosis, malaria,    are more likely to occur in those with periodontal    and mortality in childhood. Viral diseases such
sarcoidosis and several other diseases with an        disease. However, the oral pathogens causing          as hepatitis B, herpes labialis, acute herpetic
immunological basis. Other drugs that cause           periodontitis have only rarely been shown to          gingivostomatitis, cytomegalovirus and infectious
gingival overgrowth include calcium ion channel       cause endocarditis.                                   mononucleosis may also originate from oral
blocking agents used in the treatment of angina                                                             contact.
                                                      Prevention of infective endocarditis from
pectoris and postmyocardial syndrome, such as
                                                      oral bacteria depends on limiting the entry           Disease-causing microorganisms can be spread
nifedipine and verapamil, and phenytoin (sodium
                                                      and dissemination of bacteria through the             by direct contact (with saliva or blood from
5,5-phenylhydantoin), used in the treatment
                                                      bloodstream and lymphatic circulation. Antibiotic     the mouth) or indirect contact (with saliva- or
of epilepsy and also for management of other
                                                      prophylaxis for dental procedures that are            blood-contaminated surfaces, including hands or
neurological disorders. Treatment often consists
                                                      likely to provoke bacteremia has historically         lips), droplet infection (from coughing, sneezing
of using an alternate drug, although this is not
                                                      been recommended. A recent study, however,            or even normal speech), or by aerosolized
always possible. Conservative periodontal
                                                      suggests that receiving dental treatment does         organisms. These organisms can be inhaled,
therapy can reduce the inflammatory component
                                                      not significantly increase the risk of infective      ingested or taken in through mucous membranes
of enlargement, but surgery is often required.
                                                      endocarditis, even in patients with valvular          in the eyes, nose or mouth or through breaks in
Drugs that cause systemic bone marrow
                                                      abnormalities. Further research is necessary          the skin. A number of diseases can be spread via
suppression, oral mucosal injury or salivary
                                                      to determine whether some heart or valvular           oral sexual contact, including gonorrhea, syphilis,
compromise collectively promote the risk for
                                                      conditions or certain dental procedures, such as      trichomoniasis, chlamydia and mononucleosis.
clinical infection. In addition, antibiotics and
                                                      surgery or scaling, would require coverage with
concurrent steroid therapy often alter oral flora,                                                          As mentioned earlier, the oral mucosa and saliva
                                                      pre-procedural antibiotics and others would be
thereby creating an environment for fungal                                                                  provide significant defense against disease
overgrowth. In high-risk cancer patients, fungal                                                            transmission. Epidemiological and animal studies
infection can cause severe morbidity and even         oral infections and respiratory disease               are providing evidence, however, that the oral
death.                                                Pathogens in the oral cavity can also gain            cavity may be the site for transmission of serious
                                                      access to the airway, sometimes with serious          systemic infections despite the protective factors
infective endocarditis                                                                                      in saliva. Infection with HIV provides a case in
                                                      consequences. In adults, bacterial pneumonias
The purported connection between oral                                                                       point.
                                                      are strongly associated with aspiration of
infection and a specific heart disease, infective
                                                      bacteria into the lower respiratory tract, which      Early in the 1980s, when AIDS was first
endocarditis, has a long history. Endocarditis is
                                                      is normally sterile. Common respiratory               identified in the United States, concern was
caused by bacteria that adhere to damaged or
                                                      pathogens such as Streptococcus pneumoniae,           expressed about casual (i.e., nonsexual)
otherwise receptive surfaces of the tissue that
                                                      Streptococcus pyogenes, Mycoplasma                    transmission of HIV. Detailed household studies
lines heart valves (the endocardium). Dental
                                                      pneumoniae and Haemophilus influenzae                 did not demonstrate transmission of HIV, even
and other surgical procedures may predispose
                                                      can colonize the oropharynx and the lower             when family members shared eating utensils
susceptible patients to infective endocarditis by
                                                      airway. In addition, oral bacteria including A.       and toothbrushes with an HIV-affected member.
inducing bacteremias. However, bacteremias
                                                      actinomycetemcomitans, Actinomyces israelii,          Similarly, surveillance data collected over time
from oral infections that occur frequently
                                                      Capnocytophaga spp., Eikenella corrodens,             showed no evidence of casual transmission.
during normal daily activities, coincidental
                                                      Prevotella intermedia and Streptococcus
even with chewing food, toothbrushing                                                                       Only one nonoccupational episode of HIV
                                                      constellatus can be aspirated into the lower
and flossing, contribute more substantially                                                                 transmission has been attributed to blood-
to the risk of infective endocarditis. Oral                                                                 contaminated saliva; this incident involved
organisms are common etiologic agents of              Chronic obstructive pulmonary disease,
                                                                                                            intimate kissing between sexual partners. There
infective endocarditis. For example, strains          characterized by obstruction of airflow due
                                                                                                            have been a few cases of HIV transmission from
of S. sanguis, as well as gram-negative oral          to chronic bronchitis or emphysema and by
                                                                                                            performing oral sex on a person infected with
bacteria including Haemophilus aphrophilus,           recurrent episodes of respiratory infection, has
                                                                                                            HIV, and it is also possible to become infected
A. actinomycetemcomitans, E. corrodens,               been associated with poor oral health status.
                                                                                                            with HIV by receiving oral sex. In the San
Capnocytophaga spp., and Fusobacterium                Although oral bacteria, including periodontal
                                                                                                            Francisco Options Study of men who have sex
nucleatum, have been associated with bacterial        pathogens, have the potential for causing
                                                                                                            with men identified within 12 months of HIV
endocarditis.                                         respiratory infections, the frequency and nature of
                                                                                                            seroconversion, oral transmission represented 7.8
                                                      such infections are not known and merit further
Infective endocarditis occurs with different                                                                percent of primary HIV infections. Rothenberg
incubation periods, which differ in causative                                                               et al. (1998) reviewed epidemiologic studies and
bacteria and signs and symptoms. For example,         oral transmission of infections                       reports of 38 cases of oral transmission of HIV in
Staphylococcus aureus endocarditis may have a         Besides being a portal of entry for infections,       the literature. They concluded that although oral-
rapid onset and fatal course if it affects the left   the mouth is an important source of potentially       genital conta