Tips for successful posterior resin composite restorations

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                                                                                                                     very deep (Figure 7&8).
Tips for successful                                                                                                        When the outer carious lesion is removed
                                                                                                                     according to the guide of staining with caries
                                                                                                                     detector and natural discoloration, patients don’t
posterior resin                                                                                                      feel severe pain during the caries excavation
                                                                                                                     (Figure 9). Clinical evaluation of the VAS (Visual

composite restorations                                                                                               Analogue Scale) value of the pain during the
                                                                                                                     treatment of caries revealed that the younger
                                                                                                                     patients tended to feel stronger pain than older
                                                                                                                     patients. However, the pain was much less than
                   Dr. Junji Tagami                          dentin, which is infected by bacteria and easily        the pain during a shot of local anesthesia
                   Chairman and Professor
                   Department of Cariology & Operative
                                                             stained with caries detecting dye solution, is          [Terano et al., JDR 79 abst.#1162, 2000].
                   Dentistry                                 removed, the cavity floor dentin is not sensitive,      Though various methods for diagnosing dentin
                   Tokyo Medical & Dental University         even if it is very close to the pulp. Once the          caries removal have been proposed, this
                   5-45 Yushima 1 Chome Bunkyo-ku Tokyo      intact dentin is exposed in the cavity, it must be
                   113-8549 Japan                                                                                    technique is the most practical for achieving
                   tagami.ope@tmd.ac.jp                      very sensitive because the dentinal tubules are         “minimum invasive” caries treatment.
                                                             open and transfer the stimuli to the pulp.                    After removal of the outer carious dentin,
      Because of the development of material                 Bonding with perfect sealing of the tubules is
science and cariology, it became very easy to                                                                        the cavity floor consists of the so called inner
                                                             essential for decreasing sensitivity. Furthermore,      carious dentin, which is also named as caries
obtain successful results with posterior                     cutting of sound dentin may cause pulpal
restorations using adhesive resin composites.                                                                        affected dentin. It is clearly shown that the
                                                             inflammation or hyperemia. In most cases,               caries affected dentin is not permeable (Figures
The successful results include esthetics, long               these pulpal changes recover with time,
lasting function, and of course, no                                                                                  10-13). It means that the cavity floor dentin is
                                                                            however, some cases requiring            not sensitive. The SEM picture exhibits the
post operative sensitivity of the                                           endodontic treatment may occur
tooth. At the same time, the                     Bonding with                                                        occluded dentinal tubules with mineral deposits
                                                                            because of irreversible pulpal           even after the phosphoric acid etching (Figure
procedures and manipulation of the              perfect sealing             changes.
materials should be simple and                                                                                       14). That’s why the lining is not necessary when
                                                 of the tubules                   The procedure of this              this technique is applied. The lining is
easy to reduce the operator’s                                               technique established by Dr.
technique sensitivity.                          is essential for                                                     recommended when the intact dentin was cut or
                                                                            Fusayama [New Concepts in                when the patients felt significant pain during the
1. Cavity preparation                              decreasing               Operative Dentistry, Quintessence        cavity preparation.
      Cavity preparation for the                                            Publishing, 1980] is as follows; 1.            When this minimal invasive technique for
                                                   sensitivity.             opening the cavity with high speed
adhesive restoration is extremely                                                                                    caries removal and cavity preparation is used,
simple and easy. The most                                                   cutting (Figures 1&2), 2. excavation     post operative tooth sensitivity seldom occurs.
significant reason for the post operative                    of the outer carious dentin according to the            Even when the cavities are left as it is without
sensitivity is over-cutting of dentin during the             guide of caries detector and natural discoloration      any filling, the tooth is not sensitive because the
cavity preparation. When the outer carious                   using slow speed steel burr or hand instruments         cavity floor dentin consists of the caries affected
                                                                                     (figures 3-5), 3. repeating
                                                                                     the staining of the lesion
                                                                                     and its removal until            INSIDE THIS ISSUE
                                                                                     staining becomes light pink
                                                                                     or less (figure 6). In
                                                                                     addition, the wetness of
                                                                                     the cutting debris and the
                                                                                     sensitivity of the tooth are
                                                                                     very valuable information
  Figure 1 Before treatment             Figure 3 Discoloration is seen               for diagnosing the amount        s   Continuing
                                                                                     of dentin to be removed.
                                                                                     Then the bonding and                 Education Credit
                                                                                     filling materials are applied        material in this issue.
                                                                                     without lining materials
                                                                                     even when the cavity is         Take the free exam at
                                                                                                                     www.dentrek.com/kuraray.asp


  Figure 2 Cavity is opened with high speed   Figure 4 Caries detector is applied
  diamond point
dentin with the occluded tubules.                                   recognized when you compare
                                                                    with any of the composite resins
2. Selection of the adhesive resin                                  which are used in your clinic. This
      High quality adhesive provides good                           is one of the most unique
sealing and reinforcement of the tooth                              characteristics of Clearfil AP-X.
substance and filling material. Adhesive resin                             Stickiness of the resin pastes
which exhibits strong bonding, low technique                        to filling instruments is reduced by
sensitivity and durable bond to both enamel and                     increasing the consistency of the
dentin should be selected.                                          paste in the resin materials so              Figure 9 VAS value of pain during the caries
      SE Bond is very well known as extremely                       called packable or condensable               removal and cavity preparation LA: VAS         Figure 12 Occlusal view after preparing the
                                                                                                                                                                flat surface. Lesion with the discoloration is
excellent adhesive resin for both enamel and                                                                     value during the shot of local anesthesia
                                                                                                                                                                removed according to the clinical
dentin. SE                                                                                                                                                      procedures.
Bond
consists of
two steps,
which is self-
etching
primer
application                                                                                                      Figure 10 Extracted molar with cavitated
and bonding                                                                                                      lesion
resin                Figure 5 Lesion to be removed is clearly       Figure 7 Bonding procedure is applied                                                       Figure 13 After the etching, the red dye
application.         indicated                                                                                                                                  solution infiltrated from the pulp. The dye
                                                                                                                                                                was seen only at the area of the intact
It does not                                                                                                                                                     dentin, indicating the cavity floor dentin is
require the                                                                                                                                                     not sensitive.
wet bonding
technique
since the                                                                                                                                                                 Especially in the
water rinsing                                                                                                    Figure 11 The occlusal surface was ground               cases of posterior
is not                                                                                                           and the root was also removed. The crown             restorations, the wet
necessary.                                                                                                       segment was bonded to a plastic plate and
Wet bonding          Figure 6 Removal of the outer lesion, and      Figure 8 After filling and polishing
                                                                                                                 connected to a syringe to be able to apply a
                                                                                                                 pressure from pulpal side. The pulp
                                                                                                                                                                      bonding technique is
technique is         the prepared cavity                                                                         chamber was filled with a red dye solution.          very difficult to apply,
well known                                                                                                                                                                      because
as a                                                                                resin. However, the
technique sensitive bonding                             Though various                                                                                                    configuration of
                                                                                    high consistency resin
procedure, since both the over-wet                        methods for               composites may have                                                                posterior cavities is
and over-dry condition result in                           diagnosing               disadvantages such as                                                                very complicated.
decrease of the bond. Especially in                                                 the difficulty of
the cases of posterior restorations,                      dentin caries
                                                         removal have               spreading, especially in                                                       obtaining good
the wet bonding technique is very                                                   a very small and
difficult to apply, because                             been proposed,                                                                                             adaptation between
                                                                                    complicated cavity,                                                            incremental layers.
configuration of posterior cavities is                                                                                       The
                                                       this technique is and poor adaptation to Figure 14dentindentinal tubuleswiththe caries      at
very complicated.                                                                                                affected          were occluded        mineral           Even the
                                                             the most               both cavity walls and        deposits even after the phosphoric acid
                                                                                                                                                                   consistency is very thin
      Operator technique sensitivity                                                the incremental              etching.
with SE Bond is much lower than                            practical for                                                                                           before polymerization,
                                                                                    interface.                                                                     flexural strength, Vickers
with the all-in-one type adhesive,                           achieving                      When the cavity wall
which consists of only the self-                                                                                                     hardness, and tooth brush wear resistance of
                                                           “minimum                 adaptation and voids in Class I resin Clearfil AP-X are very high. This is mainly
etching adhesive. Because of the                                                    composite restorations were
extremely simplified bonding                            invasive” caries                                                             because of the high filler content of 85.5 weight
                                                            treatment.              investigated, it was revealed that               % (Figure 15). Barium glass is used as the filler
procedure of the all-in-one type                                                    thick-consistency composite had
adhesives, both performance of                                                                                                       particles and this glass is relatively soft
                                                                                    more problems related                                                           compared to silica filler
bonding and technique sensitivity are generally                    to voids and wall adaptation than
sacrificed.                                                                                                                                                         particles. Because of
                                                                   the medium and thin consistency                                                                  this relatively soft filler,
3. Selection of the resin composite                                composites [Opdam et al., Dental                                                                 polishing of this resin is
      Clearfil AP-X, which is a heavy filled semi                  Materials 12:230-235, 1996].                                                                     very easy.
hybrid type resin composite, was developed for                            Thus, Clearfil AP-X, which can
both anterior and posterior restorations.                          be classified as a medium-                                                                       4. Long term clinical
      The consistency of Clearfil AP-X must be                     consistency resin composite, can                                                                 performance
felt relatively thin compared to most posterior                    be said to be very easy to fill into           Figure 15 SEM of the AP-X, showing the
                                                                                                                                                                           In most of the
resin composites. However, Clearfil AP-X is not                    cavities of posterior teeth and to             heavily filled with various sizes of fillers.     papers reporting the
sticky to the instruments. This unique property                    obtain excellent wall adaptation                                                                 longevity of posterior
was achieved by an original technology, named without voids. This property is also                                                                                  resin restorations, the
“interfacial boundary control” between filler                      advantageous when the incremental filling                         wear of the composite resin was not a
particle and matrix resin. It is very easily                       technique is applied to deep cavity restorations, significant reason for the replacement of that
2
restoration. The main cause of failure for                         Technique sensitivity                                                                      incomplete removal of
composite restoration is usually secondary caries                        Miyazaki et al. [American                                                            water from the hybrid
around the restorations. To increase the                         Journal of Dentistry 13:101-104,                                                             layer and insufficient pen-
longevity of the restorations, the refurbishing of               2000] also reported the larger varia-                                                        etration of the resinous
the restorations is believed to be very effective                tion in bond strength of an adhesive                                                         material into the collagen
                                                                 with total etching and wet bonding                                                           layer are considered to be
[Mjor, Adhesive Dentistry 19:236, 2002].                                                                                                                      main causes of the degra-
      The survival rate of the composite                         technique than a self etching adhe-
                                                                 sives (Figure 4). In the case of the                                                         dation of the hybrid layer.
restoration in posterior teeth was reported to be                wet bonding technique, both over              Figure 4 Dentin bond strengths(MPa) of         As the result, the quality
higher than that of cast restoration [Kubo et al.,               wet and over dry conditions result in         adhesives with a self-etching primer and       of the hybrid layer should
Japan J Conserv Dent.44:802-809, 2001]. The                                                                    phosphoric acid, obtained by the well
                                                                 the decrease of the bond.                     experienced operators, untrained clinicians    be inferior in the case of
calculation was based on the results of 19 years                         A new type of bonding materi-         attended a continuing education program, and   total etching technique
clinical assessment. This result is enough to                    al, an all-in-one type adhesive, con-         the dental students.                           and/or wet bonding tech-
assure the propriety of the Fusayama’s                           sists of a real one-step bonding pro-                                                        nique.
technique. The recent materials can be expected                  cedure. The self-etching adhesive is                                                               There might be a
to exhibit much better results than the reported                 applied and cured. The adhesive has                                                          concern if it is safe to
survival rate at 19 years, approximately 80 %,                   to include some amount of water to                                                           leave the acidic primer on
                                                                 be acidic, and it has to be polymer-                                                         the tooth surface, since
because of the improvements of the materials.                                                                                                                 water rinsing is not
                                                                 ized with dissolved smear layer.
                                                                 Although the bonding procedure is                                                            applied after the applica-
What is Clearfil SE Bond?                                        simplified, the technique sensitivity
                                                                 and bonding performance seem to               Figure 5 Long term dentin bond strengths
                                                                                                                                                              tion of the self etching
                                                                                                                                                              primer. Fortunately, a
Concept of SE Bond                                               be sacrificed. In fact, these all-in-one      (MPa) of a conventional adhesive with acidic   seven-year clinical evalua-
      The technology of self etching primers was                                                               conditioner and adhesive, and a product with
                                                                 adhesive resins demonstrated lower            the self-etching primer.                       tion of an adhesive using
developed by Kuraray Medical Inc. This was                       bonding than adhesives with a two-                                                           the self-etching primer,
achieved by the development of the so called adhe- step self-etching primer [Nakaoki et                                                                       Clearfil Liner Bond 2,
sive resin monomers, named MDP or Phenyl-P                       al., 79th IADR, Abst.#1815, 2001].                                                           revealed excellent results
(Fig. 1). The adhesive resin monomers includes the Another recent study revealed that                                                                         without any de-bonding,
acidic part, that is phosphate. Because of this                  SE Bond showed the most stable                                                               nor pulpal response
acidic part, the primer solution containing the                  and strong bond when compared                                                                [Akimoto et al., Japanese
MDP becomes acidic, and can etch the enamel                      with an adhesive with phosphoric                                                             Journal of Conservative
and dentin surface.                                                                acid etching (Single                                                       Dentistry 2001]. Enamel
      The wet bonding                                                              Bond) and an adhe-                                                         and dentin are very strong
technique is required only                                                         sive of all in one sys-                                                    buffers against the acid.
when the acid is applied                                                           tem (Touch & Bond)                                                         After application of the
and rinsed with water. In                                                                                       Figure 6 Phosphoric acid etching provided
                                                                                   [Nikaido et al.,31st         the typical etching pattern of the            primer for 20 seconds, the
the case of the bonding                                                            AADR, 2003]. Even            longitudinally cut enamel prisms              acidity of the primer must
procedures using the self                                                          when students with-                                                        be decreased dramatically.
etching primer, the uncer-                                                         out the experience of                                                      The excess of the primer
tain method of wet bond-                                                           using adhesive resins                                                      solution is also removed
ing technique is not                                                               prepared the speci-                                                        by air blasting. If it is
                                                                     developed
required since the collagen Figure 1 Adhesive resin monomers Phenyl-P,
                                 by Kuraray Medical Inc., MDP and                  mens, the best                                                             harmful to the dentin/pulp
fibers are already incorpo-      which include the phosphate bases. Because        results were obtained                                                      complex, the excellent
rated with the resin             of the acidic part, they are named to be acidic
                                                                                   with SE Bond. Also,                                                        clinical performance with-
monomers in the primer           monomer, which enables to reduce the pH of
                                 the primer solution.                              SE Bond exhibited                                                          out post operative sensitiv-
solution. The bonding pro-                                                                                      Figure 7 Self-etching primer of SE Bond       ity cannot be obtained.
                                                                                   less technique sensi-        provided relatively weak etching effect
cedure of Clearfil SE Bond                                                         tivity than the other        compared to phosphoric acid.                        The dissolved and
(Figure 2) is, application of                                                      bonding materials.                                                         softened smear layer can
self etching primer for 20                                                                The only prob-                                                      be blown away from the
seconds, drying the sur-                                                           lem with this adhe-                                                        surface when the excess
face with air blast remov-                                                         sive system is the consistency of the of the primer is removed. Also, the primer is
ing the excess primer solu-                                                        self etching primer, which is very              known to show some antibacterial effect. Even if
tions from the surface,                                                            thin. The primer flows very easily              some bacteria and smear layer remained, excellent
application of the bonding                                                         down the cavity walls, however, this clinical performance and durable bonding prove
resin, and light curing.         Figure 2 Clearfil SE Bond consists of one
                                 bottle self-etching primer and one bottle light   problem is easily solved by applying that it would not be a problem.
With this extremely simple cured adhesive                                          the primer 2 or 3 times during the
bonding procedure, very                                                                                                            Enamel bonding
                                                                                   application time [Ogata et al.,                        Another concern may be the bonding to
strong bonding to both                                                             Operative Dentistry 24:81-88,
enamel and dentin, as                                                                                                              enamel, since the acidity of the self etching primer
                                                                                   1999].                                          is considered to be much lower than that of phos-
well as to various dental
materials can be obtained                                                          Long term bond durability                       phoric acid. Actually, etching effect of the self-etch-
(Figure. 3) [Harada et al.,                                                               The bonding durability of the            ing primer is much less than that of the phosphoric
Dentistry in Japan 36: 47-                                                         adhesive with a self etching primer             acid etchant (Figure 6, 7). However, a recent study
53, 2000]. SE Bond is                                                              has been reported to be superior                revealed that SE Bond showed more stable bonding
used in the clinic for not                                                         than the adhesive with total etching to both cross-cut enamel prisms and longitudinally-
only restorative procedures                                                        technique even after 6 years (Figure cut enamel prisms than the adhesive with phos-
but also intraoral repairs       Figure 3 Bond strengths (MPa) of the SE
                                                                                   5) [Burrow et al., Adhesive Dentistry phoric acid etching (Figure 8) (Shimada et al.,
of fractured restorations,       Bond to enamel, dentin, metal, and porcelain.     19:254, 2002]. It is because of the             Operative Dentistry, 28:20-27, 2003). The phos-
secondary caries and             Alloy Primer (Kuraray Medical) and Activator      very stable hybrid layer formation,             phoric acid etching may be too strong to etch the
so on.                           (Kuraray Medical) were used for the bonding       though it is very thin. Effects of              longitudinally cut prisms, which resulted in the sep-
                                   to metal and porcelain respectively.
                                                                                                                                                                                             3
                                         Kuraray America, Inc.                                                                                                         Presorted
                                         2501 East Piedmont Road, Suite 143                                                                                             Standard
                                                                                                                                                                      U.S. Postage
                                         Marietta, GA 30062                                                                                                               Paid
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 aration of enamel prisms just beneath the bonding                      Opdam et al. (American Journal of Dentistry          dentinal fluid or precipitation of protein in dentinal
 interface (Figure 9, 10). In the clinical situation, the        11:229-234, 1998) evaluated the post operative              fluid, such as globulin and albumin, resulting in a
 cavity walls consist of mostly longitudinally cut               sensitivity with class I restorations. Post operative       reduction in dentin permeability (Tagami et al.,
 enamel prisms. As shown in the Figures 7,                                                            sensitivity was        Arch oral Biol 39 suppl: 146S, 1994). Self etching
 the SEM of the enamel after the self-etching                                                         observed with 25%      primer is expected to show the desensitizing effect
 primer application does not look great, how-                                                         of the cases re-       since the self etching primer shows the coagulation
 ever, we etch the tooth for the bonding, but                                                         stored with the ad-    of protein.
 not for the SEM.                                                                                     hesive using phos-            Based on our work, SE Bond is believed to
         Unfortunately, the uncut enamel sur-                                                         phoric acid etching,   have the best advantage in preventing post opera-
 face is much more acid resistant than                                                                whereas none of        tive sensi-
 ground enamel, and the self-etching primer                                                           the cases restored     tivity, as
 is not strong enough for strong bonding                                                              using a self etching   compared
 (Kanemura et al., American Journal of                 Figure 8 Enamel bond strengths (MPa) of SE
                                                                                                      primer, Clearfil       with the
 Dentistry, 27:523-530, 1999). In the cases            Bond and Single Bond to horizontal and axial   Liner Bond 2.          adhesives
 of the bonding of fissure sealant and direct          sectioned surfaces with the longitudinally cut        The desensi-    using
 composite veneer without cutting the                  enamel prisms, and to tangentially sectioned   tizing effect of the   phosphoric
                                                       surface with cross-cut prisms.
 enamel surface, phosphoric acid etching is                                                           adhesive resin         acid. After
 recommended.                                                                                         monomers is con-       the phos-
                                                                                                      sidered to con-        phoric acid
                          Post operative                                                              tribute to decrease    etching,        Figure 11 Incidence (%) of post-operative tooth
     In fact these        sensitivity                                                                 the post operative     the primer sensitivity after composite resin restorations
all-in-one adhesive             According to a                                                        tooth sensitivity.                                              self-etching primer,
                                                                                                                             application using the adhesives withwith light cured
                                                                                                                                             phosphoric acid etching
                          clinical evaluation of                                                      The desensitiz-        has a pos- adhesives, or chemical cured adhesives.
   resins demon-          post-operative tooth                                                        ing effect of          sibility of
    strated lower         sensitivity after resin                                                     adhesive primer        decreasing the sensitivity; however, the etching
                          composite restora-                                                          application to         increases dentin permeability by enlarging tubule
    bonding than          tions, teeth restored        Figure 9 Laser scanning microscopic image of   hypersensitive         diameters. SE Bond, which does not require any
  adhesives with          with the materials uti- the bonding interface between enamel and            teeth was con-         strong acidic treatment, and is not technique sensi-
                          lizing self-etching          Single Bond showing the crack propagation
    two-step self-                                     along the prisms under the interface.          firmed in clinical     tive as compared to the wet bonding technique,
                          primer showed the                                                           studies (Tagami        provides a successful restoration. s
  etching primer.         less post-operative                                                         et al., Dental
                          sensitivity than bond-                                                      Materials Journal
                          ing materials using                                                         6:201-208, 1987,
 phosphoric acid etching (Figure 11,                                                                  Suda et al., Dental
 Unemori et al., Journal of Dentistry, 29:7-                                                          Materials Journal      Published by Kuraray America., Inc.
 13,2001). It is considered that adhesive                                                             9: 163-166,            101 E. 52nd Street
 materials with self-etching primer have the                                                          1990). The mecha-      New York, NY 10022
                                                                                                                             (800) 879-1676
 advantage of better bonding performance                                                              nism of the desen-
                                                       Figure 10 Laser scanning microscopic image of
 and less technique sensitivity in the bond-           the bonding interface between enamel and SE    sitizing effect was    www.kurarayamerica.com
 ing procedure compared to those materials             Bond showing the tight bonding without crack   postulated due to      News-05/03 Printed in USA 05/03
 with phosphoric acid etching.                         propagation.
                                                                                                      the coagulation of

				
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