Composite resin shrinks when cured; statistics show that the shrinkage may be between 2 and 9% by volume. This is a significant statistic and must be addressed, or the restoration will impart a high degree of stress on the remaining tooth structure.1-3
Dental amalgam has traditionally been used to restore typical class I and II lesions. With the use of pins, many teeth with lost cusps were also restored to form and function with this material. It was not uncommon to use several pins to support an amalgam restoration replacing 1 or more cusps.4-6 Today, dentists are increasingly using composite resin materials to restore posterior teeth. Patients demand not only tooth-colored fillings, but mercury-free fillings as well. However, composite resin material does not allow us the luxury of total tooth fabrication unless we first pre-shrink the material.1,2,7
Pre-shrinking by post-curing permits the clinician in a single office visit to restore teeth that have been severely compromised by decayed or fractured cusps.1,3,7 No pins are required, since the composite restoration can be bonded into place not only to restore the tooth to form and function, but also to give a very aesthetic appearance to the newly restored tooth.5
Traditionally, a large restoration such as an onlay was accomplished in 2 visits: the first visit would involve the preparation and impression, and the second visit would involve the installation of the onlay.3 Using the direct resin onlay technique described in this article, the clinician is able to restore a wide variety of dental problems in a single visit, without laboratory support.1,2,7
THE TECHNIQUE: CASE REPORT
|Figure 1. Preoperative view.|
The patient presented to the office with the chief complaint of discomfort in tooth No. 30. Examination revealed an old composite filling that had broken and a distal split that could be causing the discomfort when the patient chewed (Figure 1). Radiographic evidence revealed no other pathology, and the patient was informed about the treatment options available, which included a crown or an onlay. We decided to treat both teeth Nos. 29 and 30 in one visit, but for the purposes of this article, we will discuss tooth No. 30.
Because more than 50% of the intracoronal portion of the tooth required restoration, laboratory support was necessary…or was it? Would the restoration have to be constructed using an indirect technique with at least 2 office visits?
The patient informed us that he would be leaving the next day for a 6-week business trip to Africa and would not be able to wait the 2 weeks necessary to receive the prosthesis back from the laboratory. With the Direct Resin Onlay Technique, the clinician can be the technician and construct a strong aesthetic restoration in the office in about an hour. The patient agreed to this treatment plan, and treatment began immediately.
|Figure 2. Rubber dam placed.|
|Figure 3. Burs used for tooth preparation.||Figure 4. Preparation under dam.|
First, the patient was anesthetized with lidocaine 2% 1/100,000 epinephrine, and the rubber dam was applied (Figure 2). Preparation of the tooth was accomplished under a rubber dam (Flexi Dam, Coltène Whaledent) to keep the patient from ingesting any particles of old restoration created during its removal. A No. 12a clamp was used to secure the dam, and the preparation was completed.5,9 An 845 KR-016 diamond (Brasseler) was used for the preparation, and a 8862-010 diamond (Axis) was used to finish the cavosurface walls (Figures 3 and 4).
|Figure 5. Preparation under dam with matrix.||Figure 6. Rough onlay.|
Next, a matrix was placed, and True-Vitality Releasing Agent (Den-Mat) was placed in the preparation (K-Y Jelly [McNeil-PPC] or glycerin is acceptable, Figure 5). The hybrid composite system Virtuoso Universal (Den-Mat) and appropriate shade were selected. One shade of Virtuoso works well in the posterior segment, as Virtuoso Universal has a chameleon effect and blends in well with the surrounding tooth structure. An amount of hybrid was dispensed that overfilled the preparation, and the onlay was packed with a large packing instrument. Alternatively, the clinician’s finger can be used (Figure 6). (The anatomical form of the onlay will be addressed later.)
|Figure 7. Allegro curing light.||Figure 8. Translux post-curing oven.|
The composite was cured with the Allegro LED curing light (Den-Mat) buccally, lingually, and occlusally (Figure 7). The “rough” onlay was then removed for post-curing.7 Any heat-producing post-curing system is acceptable for the post-curing process because it not only light-cures, but it also heat-cures.7 The onlay was post-cured for 5 minutes4,7 using the Translux post-curing oven (Hereaus Kulzer, Figure 8). This post-curing process polymerizes and causes maximum conversion of the resin polymer. This increases the physical properties of the composite as much as 50%.6 In addition, the pre-shrinking eliminates the possibility of cusp torquing upon cementation, therefore minimizing postoperative sensitivity.7,10
|Figure 9. Onlays on pad after post curing.|
The onlay was removed from the post-curing oven and checked for integrity (Figure 9), then seated back into the tooth and checked for fit. If the onlay does not fit well, go back to the first step, relubricate the tooth with releasing agent, apply fresh Virtuoso, and cure, remove, post-cure, rinse, and try-in again. The beauty of this technique is that if the onlay doesn’t fit properly, it only takes 5 minutes to make another one.
|Figure 10. Air-abrasion device (Kreativ).|
Once the fit was confirmed, the internal surface of the onlay was micro-etched. This can be done with a micro-etcher or air-abrasion system (Figure 10). Den-Mat porcelain conditioner was applied to the internal area of the onlay for 30 seconds and rinsed off with water, and then Cerinate Prime Silane (Den-Mat) was brushed onto the portion of the onlay that would be cemented into the tooth. The silane was air-dried to volatilize solvent, and the onlay was set aside.
The rubber dam was checked for integrity, and the matrix was placed with a large wedge (Flexi-Wedge, Common Sense Dental) to “prewedge” the tooth and allow for space for the matrix and onlay.5,9 The tooth was etched with Etch and Seal (Den-Mat) for 15 seconds only,11 then rinsed for 60 seconds and disinfected with Tubulicid Red (Global Dental). The disinfecting step is intended to kill any residual bacterial contaminants remaining in the preparation.
Some may ask why a clinician should disinfect if he or she has etched with acid pH 2.0? Remember that the bacteria that caused the caries in the first place produce acids and gasses as byproducts of bacterial metabolism. Therefore, the bacteria thrive in an acidic environment; they are not killed by it. The Tubulicid Red is a good disinfecting agent that will help protect the tooth from recurrent caries.8
|Figure 11. Rough finish.|
|Figure 12. Polishing pastes.||Figure 13. Final onlay.|
The bonding agent Tenure (Den-Mat) was applied to the tooth preparation, and the dual-cure resin cement Infinity (Den-Mat) was prepared.12 The cement was placed in a Centrix syringe tip and dispensing gun, and was placed into the preparation. The onlay was seated, cured in all parameters, and finished with appropriate diamonds and carbides. A 379-023 carbide (Axis) and a 247-009 12-fluted, round-ended, ET-type finishing bur (Brasseler, Figure 3) were used to refine the anatomical form of the tooth. The occlusion was checked, and finishing was completed with appropriate discs, ultrafine polishing paste (Den-Mat), and Enamelize (Cosmedent, Figures 11 to 13).
Sometimes the clinician needs a restorative technique to provide the patient with a rapid, predictable, strong “pre-shrunk” restoration. One visit is preferable. The limitations of composite systems can be overcome with the direct resin onlay technique described in this article.
1. Abel MG. In-office inlays with today’s new materials. Dent Clin North Am. 1998;42:657-664.
2. Alavi AA, Kianimanesh N. Microleakage of direct and indirect composite restorations with three dentin bonding agents. Oper Dent. 2002;27:19-24.
3. Herrero AA, Yaman P, Dennison JB. Polymerization shrinkage and depth of cure of packable composites. Quintessence Int. 2005;36:25-31.
4. Amussen E, Peutzfeldt A. Mechanical properties of heat treated restorative resins for use in the inlay/onlay technique. Scand J Dent Res. 1990;98:564-567.
5. Summitt JB, Burgess JO, Berry TG, et al. The performance of bonded vs. pin-retained complex amalgam restorations: a five-year clinical evaluation. J Am Dent Assoc. 2001;132:923-931.
7. Loza-Herrero MA, Rueggeberg FA. Time-temperature profiles of post-cure composite ovens. Gen Dent. 1998;46:79-83.
8. Pappas M, Burns DR, Moon PC, et al. Influence of a 3-step tooth disinfection procedure on dentin bond strength. J Prosthet Dent. 2005;93:545-550.
10. Tantbirojn D, Versluis A, Pintado MR, et al. Tooth deformation patterns in molars after composite restoration. Dent Mater. 2004;20:535-542.
11. Leinfelder KF. The ever-changing world of dentinal adhesives. Dental Town. Jan 2005:38-48.
Dr. Abel is an accredited member of the American Academy of Cosmetic Dentistry, a member of the American Society for Dental Aesthetics, a fellow in the Academy of General Dentistry, and a fellow in the International Society for Dental and Facial Aesthetics. He is published both nationally and internationally and lectures on the techniques necessary for using composite resins to restore both anterior and posterior teeth predictably. He maintains a cosmetic dental practice in Rockville, Md, and can be reached at (301) 770-1447.
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