Class I Composite Resin Restoration Theodore P . Croll, D.D.S."
Composite resin materials and methods for their use have improved to the extent that long lasting Class I carious lesions on stress-bearing surfaces can be restored with predictable results. This article demonstrates a step-by-step clinical technique for placement of a Class I composite resin restoration lined with a lighthardened glass-ionomer dentin replacement foundation. Emphasis is placed on tooth isolation, thoughtful handling of the respective materials, and the importance of final sealing of the resin/enamel margins.
ince the advent of preventive resin restorations and the subsequent verification of their value,14 composite resin materials have improved substantially. Some of the newer photopolymerized composites are much more wear resistant and dimensionally stable in the moist, traumatic, 98.6"Fenvironment in which they are placed and must function. Class I occlusal surface composite resins larger than preventive resin restorations can be long lasting. If one uses a suitable composite material, places and photopolymerizes it correctly, perfects the finished surface, and obturates marginal microgaps using unfilled resin, such a bonded restoration can be an excellent alternative to a traditional silver amalgam. This article demonstrates a technique for placement of an occlusal composite resin restoration with an underlying lighthardened glass-ionomer dentin replacement foundstion.
m e 1. Occlusal pit and fissure caries is seen involving this mandibular first molar.
TECHNIQUE Class I composite resin restoration of a mandibular first permanent molar is illustrated in Figures 1 to 22.
'Private Practice, Pediatric Dentistry. Doylestown, Pennsylvania: Clinical AssociateProfessor,Department of Pediatric Dentlshy.Universityof PennsylvaniaSchoo1ofDentalMedicine,Philadelphia.Pennsylvania:Adjunct Clinical Professor. Department of Pediatric Dentistry. University of Texas Health Science Center at Houston (Dental Branch), Houston, Texas Address reprint requests to Theodore P. Croll. D.D.S., Georgetown Cornmom. Suite 2, 708 Shady Retreat Rd.. Doylestown, PA 18901-3897 0 1992 Decker Periodicals Inc.
we 2' After appropriate
injections and Illbber dam isolation, initial preparation is made using a water-cooled high-speed No. 33 1/2 inverted cone bur.
Composite Resin Restoration
Figure 3. Caries is debrided with slow speed round burs and the preparation extended to include all infected grooves.The last traces of caries can be seen in the buccal aspect of the Preparation.
Figure 6. Using a slow speed inverted cone bur, the walls of the preparation are cleared of the glass-ionomermaterial, and the preparation completed with cavity walls converging toward the occlusal aspect.
Figure 4. After mixing Vitrebond (3M Dental Products Division. St. Paul, MN) according to manufacturer’s instructions, the material is placed in a Centrix syringe tip (Centrix. Inc.. Milford. 0 and injected into the cavity preparation. There is no pretreatment of exposed dentin surfaces.
Figure 7. The prepared Vitrebond dentin liner/foundation is shown.
Figure 5. After the Vitrebond material is spread throughout
Figure 8. Forty percent phosphoric acid conditioner is placed on the enamel surfaces by injection syringe.
the preparation in its creamy consistency, the material is hardened with 40 seconds exposure to the visible light beam.
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 5 September/October 1992
Figure 9. The phosphoric acid conditionerremains in place for 30 seconds while being agitated with a ball burnisher.
Figure 12. The preparation is shown after application of the unfilled enamel resin bonding agent.
Figure 10. After 20 seconds of rinsing and drying. unfilled enamel resin bonding agent is painted into the preparation and upon adjacent enamel surfaces.
Figure 13. Aflrstincrementofwear-resistantcompositeresin
Figure 11. If excessive resin bonding agent is inadvertently placed, the thick end of an endodontic paper point can be used to absorb the excess.
Figure 14. Using a ball burnisher the fist increment of
i s injected with care to avoid entrapment
of air bubbles.
composite resin is compressed into the cavity preparation.
Composite Resin Restoration
Figure 15. The resin is polymerized with 30 seconds light application from the lingual, 30 seconds application from the buccal direction, and 30 seconds additional light exposure from the occlusal aspect.’
Figure 18. The occlusal composite resin is shown prior to application of the final sealant layer.
Figure 19. After application of 40% phosphoric acid gel for 30 Figure 16. The second increment of resin is injected.
seconds followed by washing and drying. a light-polymerized clear resin sealant is painted over the resin and resin/enamel margins.
Figure 17. After an additional 60 seconds exposure to the light, occlusal surface sculpting is performed.Very sharp large round burs can be used for reduction of excess material, and slowspeed large invertedconeburs can be used to carve occlusal anatomic form.
Flgure 20. The liquid sealant should reunpolymerized for 10-15 seconds to permit marginal microgap penetration by capillary action. The sealant layer is then polymerized by light application for 30 seconds.
.JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 5 September/Ortober 1992
Pigure 21. The final restoration is shown before removal ofthe rubber d a m .
Figure 23. A 3X-year-old occlusallingual composite resin with a glass-ionomer dentin replacement base is shown.
Pysure 22. Occlusal relationships are assessed with articulating paper. Any required adjustments are made at this time.
EYgure 24. A large occlusal Class I composite resin is shown 5 years after placement. This restoration replaced a large defective silver amalgam restoration, and was documented in 1989.7
DISCUSSION 2. The restoration is repairable.* 3. The composite resin/glass-ionomer restoration is mercury free, which is a desirable feature to some patients, parents, and dentists. 4. Composite resins are tooth colored. 5. Composite resin restorations can be resealed as needed to perfect margins and improve surface quality.
The disadvantages to restoring Class I carious lesions with composite resin overlying glass-ionomer dentin foundations are few but important. Placement of the respectivematerials requires an exacting technique and isvery time consuming. Treatment usually takes at least twice as long as for placement of an analogous silver amalgam restoration and therefore fees for the composite resins/glass ionomer restoration should be higher. The other chief disadvantage is that moisture and humidity control needed to avoid contamination of the bonded materials is absolutely essential. The composite resin/glass-ionomer Class I restoration would be difficult to perform without use of a rubber dam. The advantages to composite resin Class I restorations include:
Selection of materials for both dentin replacement and enamel replacement is most critical in this technique. The ideal dentin replacement material would bond to tooth structure, harden rapidly, be insoluble in oral fluids, be biocompatible with the dental pulp, have sufficient compressive strength early on to withstand occlusal loading of the overlying composite resin, be radiopaque, and be easily placed. The composite resin selected would ideally be very wear resistant, have minimal polymerization shrinkage, have a coefficient of
1. The respective filling materials are bonded, so
marginal microleakage is minimized. 152
Composite Resin Restoration
thermal expansion close to that of tooth structure, be dimensionally stable to resist loading forces and the influence of the moist intraoral environment, and have good handling properties. Vitrebond glass-ionomer liner/base was used in this case because of its rapid light-hardening reaction and excellent clinical performance to date. PertacHybrid (ESPE - Premier Sales Corp., Nomstown, PA) was used because of its high filler content, low moisture sorption, low polymerization shrinkage, and hard surface resulting from a finely ground quartz filler. Three years of clinical use have shown excellent results with Pertac-Hybrid (personal communication, Dr. D. Maltz, Dr. R. Cavanaugh). Class I composite resin restorations differ from preventive resin restorations, first advocated by Simonsen,’ chiefly in the extent of carious involvement and preparation. In many preventive resin restorations, caries is limited to enamel in pits and fissures, so extended preparation and glass-ionomer dentin replacement may be limited to local areas or not needed at all. It is prudent for the dentist to debride all stained regions in pits and fissures to assure complete removal of carious enamel and dentin. One cannot assess caries penetration without full bur cut investigation of stained Class I regions. It should also be recognized that traditional bur cut retention form is included in the preparation. When mechanical undercuts are used for retention, supplemented by dentin and enamel bonding of the restorative materials, retention is optimized and marginal leakage minimized. Undercut retention form may also help to reduce the dimensional changes that occur during photopolymerization. That possibility should be studied in uitro. A photopolymerized composite resin, the full thickness of which will be more than about 1 mm, should probably be placed in several increments (Figs. 13-16). Incremental placement reduces overall dimensional alterations of the resin mass due to the influence of the polymerizing light beam.g.10Even though incremental insertion takes a bit longer, the resultant resin/tooth interface is enhanced. The final sealant application (Figs. 18-20) is critical to success of a class I composite resin restoration (Figs.
23 and 241.’ Not only does the sealant layer perfect the resin surface after occlusal sculpting and finishing of the hardened resin,I*but marginal microgaps are also obturated.’*Marginal microimperfections in composite resin restorations, which can be seen only microscopically, should be regarded in the same light as enamel pits and fissures that need to be sealed with acid etch retained bonded resin sealant material. If the final sealant layer is not placed, the patent marginal opening will predictably permit bacterial penetration, which can lead to dental caries.
REFERENCES 1. Simonsen RJ