Placing permanent ceramic restorations in our patients’ mouths is an everyday occurrence for the restorative dentist. These restorations help to restore lost tooth structure, stabilize the occlusion, replace missing teeth, and improve esthetics. The final surface texture must be smooth and polished for patient comfort and to prevent damage to opposing teeth.
The critical parts of finalizing the restoration are ensuring an excellent fit, proper occlusal contacts, desensitization of the prep, proper cementation, and clean-up. The provisional restoration is removed from the tooth and the provisional cement is removed from the tooth surface. The tooth preparation must be adequately cleaned. This is best accomplished with sandblasting the tooth structure with 27-micron aluminum oxide in a microetcher to ensure clean healthy enamel and dentinal surfaces, which will improve bond strength. Prior to cementation the tooth must be desensitized, and the dentinal tubules sealed with a product such as G5 (Clinician’s Choice). G5 is bactericidal and will prevent post-operative sensitivity. All residual cement must be removed and one must prevent tooth desiccation prior to final cementation.
Attention is then directed to the occlusal surface. If occlusion is too low, this would be evident during the try-in phase. At this point, additional ceramic material should be added to the occlusal surface to ensure proper centric stops and no drifting of opposing teeth. This may involve returning the restoration to the lab. However, when occlusion is too high, adjustments must be finalized to obtain a highly polished surface. A rough surface can collect stain, become an irritation to the tongue, and more importantly, cause abnormal wear on the opposing teeth. It has been shown that even a glazed surface from the lab can cause unwanted opposing tooth wear. A hand polished surface is best. The following is a polishing system that is very effective in achieving a highly polished surface on the porcelain restoration chairside.
The A.S.AP. Indirect+ system (Clinician’s Choice) is an excellent choice for polishing zirconia, lithium disilicate and many other ceramic surfaces. (FIG 1)
Zirconia crown after diamond bur adjustment.
The A.S.AP. system really is an “all surface access polisher” because the feather edge of the discs allows polishing the smooth surfaces and into deep grooves and crevices. Occlusal verification starts with an 8-micron articulating paper marked in centric and lateral excursions. After the adjustment is completed, often with high-speed burs and finished with an extra fine high-speed diamond, the next step is to use the diamond-impregnated adjusters. (FIG 2)
Diamond-impregnated adjusters intraorally.
They come in three different shapes for adjustment of all the crown surfaces. These adjusters are used to remove the scratches left from the adjustment burs. A moderate amount of hand pressure will remove deeper scratches whereas light pressure will remove the superficial scratches. This takes about 1-2 minutes. (FIG 3)
After use of diamond impregnated adjusters.
Once the scratches are removed and the occlusal contacts are correct, the restoration is then polished. The system includes diamond-impregnated wheel pre-polishers (blue) and final polishers (pink). The polishers come in both intraoral contra angle latch polishers and extraoral lab wheels for a straight nose cone.
Initial adjustments can be done extraorally and after cementation and final verification, the contra-angle polishers and be used intraorally as needed. As with the adjusters, the pre-polishers and final polishers also require light to moderate pressure to finish and polish. The pre-polishers take about 1 minute to smooth the porcelain, and the final polishers take about 30 seconds for a high shine. (FIG 4, 5, 6 and 7)
Use of blue pre-polisher.
After use of blue pre-polisher, dull smooth
Use of pink final polisher.
After complete polishing, for a high gloss surface.
The adjusters, pre-polishers and final polishers can then be autoclaved to be reused. They have excellent longevity and a low wear rate, allowing them to be used on many patients and many restorations.
Other uses of the A.S.A.P. Indirect+ Polishers are everyday composite restorations, provisional crowns, and removable and fixed hybrid prostheses.
The author suggests after cementation on the most posterior teeth, to check the occlusion using a bi-manual manipulation technique of the mandible. This will ensure the condyle is fully seated in the joint and there are no premature contacts or interferences. The patient will have an excellent ceramic restoration that should last several years.