Fracture of porcelain-veneered structures in fatigue.
Porcelain-veneered crowns are widely used in modern dentistry, and their fracture remains problematic, especially in all-ceramic systems. We hypothesized that substructure properties have a significant effect on the longevity of porcelain-veneered crowns. Flat porcelain/metal or porcelain/ceramic structures were cemented to dentin-like composite, and a mouth-motion cyclic load of 200 N was delivered by means of a tungsten carbide spherical indenter (r = 3.18 mm), emulating occlusal loading on crowns supported by dentin. Findings indicated that porcelain on a low-hardness gold-infiltrated alloy was vulnerable to both occlusal surface contact damage and porcelain lower surface radial fracture, while porcelain on a higher-hardness palladium-silver alloy fractured chiefly from occlusal surface damage. The advantage of a high-modulus metal substructure was less pronounced. Fracture in the porcelain/zirconia system was limited to surface damage in the veneer layer, similar to that in the porcelain/palladium-silver system. Bulk fracture, observed in veneered alumina layers, was not found for zirconia.
Kim
B
B
Department of Biomaterials and Biomimetics, New York University College of Dentistry, 345 East 24th Street, New York, NY 10010, USA.
Zhang
Y
Y
Pines
M
M
Thompson
V P
VP
D001732:Bite Force; D002484:Cementation; D003442:Crowns; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D004548:Elasticity; D008409:Mastication; D016876:Metal Ceramic Alloys
D016876:Metal Ceramic Alloys; D003776:Dental Porcelain