Porcelain-veneered computer-generated partial crowns.
OBJECTIVE
It would be advantageous to be able to use computer-aided design and manufacturing to fabricate a restoration that can be layered with a conventional porcelain veneer in the occlusal region, thus optimizing esthetics, function, and strength. This case study reports the laboratory technique and the clinical performance of 38 partial crowns fabricated with computer technology and veneered with porcelain.


METHODS
Twenty-one mandibular and 17 maxillary molars in 27 patients were prepared for partial crowns. The occlusal surfaces were lowered (1.5 to 2.0 mm), deep shoulders (1.5 mm) were prepared around the functional cusps, and 1.0-mm-deep shoulders were prepared in the proximal gingival regions. The nonfunctional cusps were prepared with an occlusal shoulder at approximately a right angle with the axial surfaces of the seat. In the computer-aided design procedure, the occlusal table was reduced to 1.4 mm above the preparation surface. The marginal ridge points, the marginal ridge line, the equator line, and the fissure line heights were adjusted accordingly.


RESULTS
The lowest occlusal table thickness was 1.1 mm in six partial crowns, 1.2 mm in 26 partial crowns, and 1.3 mm in six partial crowns. The lowest occlusal table thickness of the porcelain veneers varied between 0.4 and 0.6 mm. The total occlusal table thickness thus was 1.5 mm or more. Clinically, no fractures occurred during an observation period varying between 1 and 4 years after placement.


CONCLUSIONS
Computer-aided design and manufacturing technology is also convenient for partial crown preparation design with shoulder finish lines.
Denissen
Harry W
HW
CAD-CAM Research, Department of Oral Function and Prosthetic Dentistry, Academic Center for Dentistry, Amsterdam, The Netherlands. H.Denissen@acta.nl
El-Zohairy
Ahmed A
AA
van Waas
Marinus A J
MA
Feilzer
Albert J
AJ
D002484:Cementation; D003116:Color; D017076:Computer-Aided Design; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D004955:Esthetics, Dental; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008963:Molar; D055095:Optics and Photonics; D013314:Stress, Mechanical; D013499:Surface Properties; D013674:Technology, Dental; D019246:Tooth Preparation
D003776:Dental Porcelain