Katie Sweeney
05/05/06
Biological Phenomenon
Introduction
Biofilms form when bacteria adhere to surfaces in aqueous environments and
begin to excrete a slimy, glue-like substance that can anchor them to all kinds of material
such as metals, plastics, soil particles, medical implant materials, and tissue. A biofilm
can be formed by a single bacterial species, but more often biofilms consist of many
species of bacteria, as well as fungi, algae, protozoa, debris and corrosion products.
Essentially, biofilm may form on any surface exposed to bacteria and some amount of
water. Once anchored to a surface, biofilm microorganisms carry out a variety of
detrimental or beneficial reactions, depending on the surrounding environmental
conditions. Dental plaque is a mixed microbial biofilm growing on teeth and is the prime
contributory agent of the two main oral diseases, dental caries and periodontal disease.
The microbial composition of plaque varies between individuals and the location on the
tooth, and generally reflects the complex nature of the ecology of the mouth.
The major sites of plaque accumulation are in the fissures of molar teeth, in the area
bounded by the margin of the gum and the tooth and between adjacent teeth. This is
where our samples will be taken from using toothpicks. In this experiment we will look
at the accumulation of plaque buildup under four different conditions. Gum chewing in
combination with brushing, will be evaluated to see if one is more effective then the
other. Therefore we look to see if changes in dental hygiene such as gum chewing, or
brushing more then twice a day, decrease the overall accumulation of plaque in the
fissures of molar teeth, regardless of diet.
Methods
In this experiment we will test the build up of biofilm on the teeth of 8 subjects.
This will be done over a 1 week period. To begin, an initial scraping of all patients’ teeth
will be done, in the morning prior to brushing. A tooth pick will be used for the
scrapings. The fissures of molar teeth, the area bounded by the margin of the gum and
the tooth and between adjacent teeth will be scraped. Three of the subjects, chosen
randomly, will then habitually brush every morning, chew gum after every meal, and then
once again at night before sleeping. Four other subjects will brush in the morning and at
night, with no gum-chewing throughout the day. One subject will brush once in the
morning and chew gum after every meal without brushing at night. The plaque index
chart will be used to determine the amount of plaque on the six chosen teeth to be scraped
(Figure 1, Table 1).
The morning of the seventh day, before brushing, plaque will be scraped from the fissures
of the molars, the margin of gum and the tooth and between adjacent teeth, from all 8
subjects. You will then plot the initial index of plaque and the final index of plaque
versus time for each subject to show the change, if any, on an individual basis. The next
graph will have the mean weight of plaque build up for each group of subjects, those who
chewed gum and brushed, those who brushed, and those who chewed gum, plotted
against time. Any change in point increase by .5 or more of a point is significant.
Results:
The gingival margin of the highlighted teeth, shown in figure 1, was scraped with
a toothpick. A score from 0-3 was assigned to each of these teeth. Zero meaning no
plaque, 1 meaning some buildup seen on the toothpick, 2 meaning buildup seen by the
naked eye, and 3 meaning a film covering the gingival pocket made up of soft debris
(Table 1). Group 1 containing, the 3 individuals who brushed twice a day and chewed
gum after each meal, showed a significant mean decrease of 0.7 in plaque buildup over
the 7 day period (Figure 2). Individually, one out of the three individuals showed a point
drop in plaque accumulation which is very significant (table 2). Group 2 showed a 0.5
point increase in mean plaque buildup when initial mean accumulation was compared to
the final mean accumulation (Figure 3). Of the 4 individuals in this group, one showed a
point increase in plaque buildup (Table 2). Group 3 also had an increase in plaque
accumulation. The one individual in this group showed a point increase in plaque build
up which is significant (Figure 4).
Figure 1. Diagram of teeth used for plaque buildup analysis
Table 1. Index score used to quantify plaque accumulation on observed teeth.
Scores Criteria
0 No plaque
1 A film of plaque adhering to the free gingival margin and adjacent area
of the tooth. The plaque may be seen in situ only after application of
disclosing solution or by using the toothpick on the tooth surface.
2 Moderate accumulation of soft deposit s within the gingival pocket, or
the tooth and gingival margin which can be seen with the naked eye.
3 Abundance of soft matter within the gingival pocket and/or on the tooth
and gingival margin.
Table 2. Scores used to indicate plaque accumulation for each individual
Initial Final Initial Mean Final Mean
Group 1 2, 2, 3 2, 2, 2 2.3 2
Group 2 2, 3, 2, 2 2, 3, 3, 3 2.25 2.75
Group 3 2 3 2 3
Group 4 2, 2 2, 2 2 2
Figure 2
2.35
2.3
Mean point index
2.25
2.2
2.15 Group 1
2.1
2.05
2
1.95
0 2 4 6 8
Time (days)
Figure 2. Demonstrates the decrease in group 1 of plaque buildup over a 7 day period.
They brushed twice a day and chewed gum after every meal. A point scale of 0-3 to
quantify plaque buildup was used.
Figure 3
3
2.5
Mean point index
2
1.5 Group 2
1
0.5
0
0 2 4 6 8
Time (days)
Figure 3. Demonstrates the plaque increase in group 3. They brushed twice a day
without gum chewing.
Figure 4
3.5
3
mean point index
2.5
2
Group 3
1.5
1
0.5
0
0 2 4 6 8
time (days)
Figure 4. Shows a point increase in the individual who brushed once a day with gum
chewing after every meal.
Discussion
The results yielded the expected outcomes showing that gum chewing has an
affect on plaque buildup (Figure 2). But with regular brushing twice a day, without gum
chewing, plaque began to increase (Figure 3). With gum chewing after every meal and
brushing once a day, plaque also increased (Figure 4). These results show that both
brushing and chewing are necessary in order to decrease plaque accumulation in the
mouth. In group 1, there was a drop in plaque accumulation from the initial count to the
final after brushing twice a day and chewing gum after every meal. This shows that gum
chewing helps to decrease plaque buildup, but only in conjunction with brushing twice a
day. Chewing sugar-free gum after a meal stimulates the production of saliva, which
helps to neutralize plaque acid. Some chewing gums contain a sugar-free sweetener
called xylitol, which suppresses certain types of plaque bacteria. To further study this
issue another factor such as intake of foods, specifying types and sugar content that
would effect the type and amount of plaque accumulated should be investigated. There is
a clear link between sugary food and drinks and tooth decay. Some types of sugar are
worse than others. The biggest offenders are those added to food during manufacturing
(refined sugars).It is how often these sugars are eaten - rather than the amount - that is
important. Avoiding refined sugars between meals gives your teeth a chance to be
rematerialized by saliva. Fruit, vegetables, cheese and milk all contain natural sugars that
are much less likely to cause decay. This makes them good alternatives to sweets, and
suitable for snacks between meals.