Damage maps for layered ceramics under simulated mastication.
Ceramic restorations, whether monolithic (single layer) or porcelain-veneered, often chip and fracture from repeated occlusal loading. Occlusion involves the opposing tooth sliding along the cuspal incline surface with an applied biting force (off-axis loading). We hypothesized that off-axis contact-load-slide-liftoff fatigue, as compared with normal axial fatigue loading, produces different fracture modes and fatigue lifespans of layered ceramics. Monolithic glass plates were epoxy-bonded to polycarbonate substrates as a transparent model for an all-ceramic crown on dentin. Off-axis and axial (control) cyclic loading was applied through a hard sphere in water, with a mouth-motion machine. The off-axis loading is more deleterious for contact-induced occlusal surface fracture, but less harmful for flexure-induced cementation surface fracture of brittle layers than the axial loading. This is because of the tangential load component associated with the off-axis loading. Clinical relevance is discussed.
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA.
J-H
JH
Kim
J-W
JW
Kim
S-W
SW
Myoung
M
M
Pines
Y
Y
Zhang
D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D003801:Dental Veneers; D019544:Equipment Failure Analysis; D008409:Mastication; D008422:Materials Testing; D008963:Molar; D033081:Shear Strength
D003776:Dental Porcelain