Dentistry, like many other professions, is seeing revolutionary changes on a consistent basis. Product improvements and the techniques that employ them are allowing dental professionals to provide more efficient dental care while satisfying the aesthetic concerns of their patients. This article focuses on using a new-generation resin cement with the chairside in-office CAD/ CAM restorative system, providing the ultimate in predictability and customization in a single dental visit.
One of our industry’s main growth areas has been aesthetic indirect restoratives, heightening the visibility of permanent resin cements with their good bond strengths and improved esthetics. 1 A traditional adhesive protocol requires an etching gel for the enamel and dentin, primer and adhesive components in multiple bottles or unit dose carriers followed by an application of cement. 2 Using this total-etch protocol, inlays, onlays and full-coverage all-ceramic restorations can be placed with confidence to meet the high aesthetic demands of today’s dental patient.
Preparation App ointment
A middle-aged woman presented with recurrent cervical decay that compromised the margins on an old porcelain-fused-to-metal (PFM) restoration on her upper-left first molar (Fig. 1). It was decided that this new restoration would be fabricated in-office with the chairside CAD/CAM restorative system, CEREC 3D® (Sirona, Charlotte, NC). The existing restoration was removed and the presence of decay was verified with a caries detector and a spoon excavator. All decay was removed from the tooth and any necessary buildups were placed to eliminate undercuts or gain proper retention form in the resulting preparations. Prior to the optical scanning of the preparations for restoration design, the soft tissue was retracted in the subgingival areas with a putty-type retraction system, Expasyl (Kerr, Orange, CA) (Fig. 2). A putty retraction system was chosen over a traditional retraction cord or other hemostatic agent because of the latter’s potential for tissue (epithelial attachment) damage and recession.3-5 After two minutes, the putty retraction material was thoroughly rinsed away with air/ water spray and dried (Fig. 3). The preparation was powdered with talc-like powder (functions as a contrast medium for taking the optical impressions), and several optical images of the preparation were taken (Fig. 4).
Restoration Fabrication
The in-office CEREC 3D® CAD/ CAM restorative system, version 3.01, was chosen for this restoration because of its high success rate6 and for the aesthetic properties, inherent strength and fracture resistance of the porcelain blocks used after oven glazing. 7 After achieving the optical images of the preparation, the restoration was fabricated using the CEREC 3D database mode. This mode allows the dentist to select the correctly shaped tooth while the computer software positions it ideally in the arch. After the restoration was milled, it was tried in to verify fit (Fig. 5) and then stained and glazed in a porcelain oven to obtain the desired surface glaze (Fig. 6). Preparing the internal aspect of the restoration involved 1) microabrading with a microether containing 50-micron aluminum oxide powder, being careful not to damage the margins, and then rinsing with water and drying for approximately five seconds; 2) application of a 9.5% hydrofluoric acid gel for one minute, rinsing with water for approximately 20 seconds, and drying thoroughly; and 3) application a silanating agent and air-drying. Because we are using the total-etch adhesive technique, an unfilled resin was applied to the internal aspect of the restoration and was gently air-dried and placed in a light-protected container until insertion.
Insertion Appointment
After proper isolation of the area with a rubber dam, the preparation was cleaned with 2% chlorhexidine, rinsed and dried, but not to the point of dessication8 (Fig. 7). The tooth was etched with 37% phosphoric acid (Fig. 8) and rinsed thoroughly. After lightly removing any excess water, the moist tooth surface was covered with OptiBond Solo Plus adhesive (Kerr, Orange, CA) and spread over the preparation for 20 seconds (Fig. 9). A moisture-free air dryer was used to evaporate the solvent in the adhesive (Fig. 10). The restoration was filled with dual-cure resin cement system, NX3 Nexus® Third Generation (Kerr, Orange, CA), and seated (Fig. 11). The excess resin cement was removed with microbrushes (Fig. 12) and tacked down midcervically on the buccal with a 4mm turbo tip in an L. E. Demetron II curing light (Kerr, Orange, CA) (Fig. 13). Flossing was done interproximally to remove as much residual uncured resin cement as possible prior to final curing (Fig. 14). Final curing was simultaneously performed buccally and lingually with two LED lights for 40 seconds (Fig. 15), followed by curing occlusally for 20 seconds (Fig. 16). Marginal finishing was performed with an 8-fluted carbide bur and composite points and cups. Interproximal finishing involved using medium and then fine composite finishing strips. The occlusion was checked and slight adjustments were performed prior to final polishing of these areas with porcelain polishing points. The final result, immediately after insertion, is shown (Fig. 17).
Discussion & Conclusion
Due to the high aesthetic demands of our patients, dentists are performing more and more tooth-coloured procedures than ever before. For this reason, educating ourselves about the latest improvements would enhance our ability to give our patients the most advanced form of treatment possible. Using the newer light-cure and dual-cure resin cements, we have the ability to place highly aesthetic porcelain (or resin) restorations with predictable results, including increased longevity and reduced sensitivity and other technique-related issues.
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Dr. Christopher Pescatore lectures on state-of-the-art aesthetic procedures, techniques, and materials, and holds a U. S. patent for a non-metallic post system to restore endodontically-treated teeth. He is a graduate of the University of Medicine and Dentistry of New Jersey — New Jersey Dental School. He maintains a full-time practice dedicated exclusively to aesthetic dental procedures in Danville, CA.
Oral Health welcomes this original article.
References
1. Miller MB: Dental adhesives. In: Miller MB, ed; REALITY: The Information Source for Esthetic Dentistry. Vol. 20, Houston, TX, REALITY Publishing Co. 2006: 197-236.
2. Freedman G: Bonding systems. Dentistry Today. Dec. 1996: 15, 68-75.
3. Azzi R, Tsao TF, Carranza FA Jr, et al: Comparative study of gingivial retraction methods. J Prosthet Dent 50 (4). 1983: 561-565.
4. Donovan TE, Gendara BK, Nemetz H: Review and survey of medicaments used with gingival retraction cords. J Prosthet Dent 53 (4). 1985: 525-531.
5. Shaw DH, Krejci RF, Kalkward KL, et al: Gingival response to retraction by ferric sulfate (Astringedent). Oper Dent 8 (4). 1983: 142-147.
6. Mormann W: The evolution of the CEREC system. Paper presented at: The CEREC 20th Anniversary Experience. October 13, 2006: Las Vegas, NV.
7. Chen HY, Hickel R, Setcos JC, et al: Effects of surface finish and fatigue testing on the fracture strength of CAD/CAM and pressed ceramic crowns. J Prosthet Dent. 1999: 82: 468-475.
8. Gwinnett AJ: Effect of cavity disinfection on bond strength to dentin. J Esthet Dent 4 (supplement). 1992: 11-13.
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Dentistry, like many other professions, is seeing revolutionary changes on a consistent basis
