Prosthodontic Insights NewsletterOctober 1999 Volume 12, Number 2Continues..Use of the Procera® CAD/CAM System for Metal abutments or margins showing through ceramic can significantly reduce the total esthetic impression of a restoration. The region where the cervical coronal portion meets the abutment is particularly critical. Bluish gingival discoloration can complicate shade adaptation to the adjacent teeth. A further difficulty is the difference between the cross section of the implant abutment and that of the root of the natural tooth. Adaptation of the natural tooth form at the site of eruption of the crown from the gingiva should be sought. Precise positioning of the implant and appropriate design of the provisional restoration play important roles in the outcome of the eruption site. The round, 4 mm diameter cross section of the implant abutment in the region of the gingiva nonetheless complicates esthetic optimization. Shine-through of the metal abutment in a restoration is hardly avoidable, particularly when the gingival taper is thin. Aluminum oxide copings veneered with a special ceramic material (AllCeram, Ducera Dental) have been fabricated for several years using the Procera® CAD/CAM system and have shown positive results. However, use of this system for fabrication of metal-free crowns supported by Brånemark single-tooth implants is new. The complete procedure involves an aluminum oxide abutment (Ceradapt, Nobel Biocare), which is custom ground and fitted with a scanned Procera® crown. The Ceradapt abutment is screwed to the Brånemark implant with a gold screw and the Procera® crown is fastened thereon. An alternative to the ceramic Ceradapt abutment is placement of a custom coping, produced using Procera®, on a Brånemark implant with a CeraOne abutment (Nobel Biocare). The combination of an individually ground CeraOne abutment and the all-ceramic crown mounted thereon offers yet another clinical/dental laboratory variant to provide optimum esthetics. Based on positive experience with Procera® crowns over a period of several years, the prognosis is good for use of the Procera® system for metal-free crowns on single-tooth implants. |
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