Restoration of an Endodontically Treated Tooth Utilizing a Single-Unit Crown and Core System
Timothy Adams, DDS
A 47-year-old female patient presented following the successful completion of endodontic treatment that involved teeth #18(37) and #19(36) (Figure 1). An extensive clinical evaluation revealed that no thermal or occlusally advanced symptoms were evident, and radiographic analysis demonstrated no obvious signs of pulpal pathology. The patient's medical history, general health, and periodontal condition were all within normal parameters. Despite undergoing a dental emergency in which teeth #19(37) and #19(36) experienced an acute flareup of pulpitis, the patient elected not to restore adjacent tooth #20(35). Based on these criteria, a decision as to the optimal method of treatment had to be rendered by the clinician.
Once the patient was anesthetized and shade taking was accomplished, intraoral camera prints and color photographs were obtained. A detailed color prescription was developed, a rubber dam was placed to facilitate moisture control, and the failing amalgam restorations and provisional materials were subsequently removed under copious irrigation. Caries detection material was applied and the remaining carious tooth structure was removed. Large horizontal cracks were evident on the buccal and lingual aspects of tooth #18(37) and the buccal aspect of tooth #19(36). While the obvious leakage and wedging effect of the restorations necessitated an aggressive preparation, the resulting dimensions were conservative in comparison to those required for traditional full-coverage crown restorations (Figures 2 and 3
). The preparations for the laboratory-fabricated composite resin restorations exhibited a minimum depth of 1.5 mm in the fissure area and a minimum isthmus width of 1.5 mm. The axial walls of the proximal box area were exposed with a cavosurface angle of approximately 60 to 80 degrees. The final impressions were made with a polyvinylsiloxane impression material. The preparations were cleansed with a 2% chlorhexidine solution and lightly air dried without desiccation prior to provisionalization with a medium-heavy material while the definitive restorations were fabricated in the laboratory (Figures 4 and 5
Following approximately three weeks of provisionalization, a rubber dam was placed and the restorations were removed. The preparations were initially cleansed with hydrogen peroxide and the 2% chlorhexidine solution. The teeth were then lightly air dried, and the definitive restorations were tried-in and clinically verified for marginal fit, contour, and interproximal contacts. The restorations were subsequently removed from each preparation and all internal aspects were cleansed utilizing phosphoric acid. A prehydrolized silane coupling agent was then applied to the interanl aspect of the restoration in order to improve the chemical bond between the polymers in the resin luting cement and the ceramic filler particles and glass fibers in the laboratory-fabricated composite. Excess silane was evaporated with an air drier following one minute of saturation.
The preparations were once again disinfected, thoroughly rinsed, and etched for 10 to 15 seconds using a 35% phosphoric acid solution. A second antimicrobial solution was used to rehydrate the dentin and decrease the bacterial count. In order to establish a hybrid layer, multiple coats of a hydrophilic dentinal primer were applied to the moist surface and allowed to penetrate into the dentin tubules. Any excess alcohol from the primer was lightly air thinned. A dual-cured, radiopaque luting resin was mixed carefully and placed into the preparations prior to seating in the restorations with firm pressure. Excess luting material was removed, and the restorations were spot tacked in place using a 3 mm light guide attached to a curing light for 10 seconds on the buccal and lingual surfaces. Excess resin was removed interproximally using dental floss. All exposed margins of the restorations were then coated with a glycerine layer to eliminate the potential formation of an oxygeninhibiting layer. Final polymerization was achieved using a plasma arc light. Excess polymerized cement was removed utilizing a curette and carbide and diamond finishing burs. Proper occlusion and anatomy were established, and final polishing was accomplished. The postoperative evaluation revealed two aesthetic restorations that exhibited optimal form, function, and strength (Figures 6 and 7
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