Sliding Contact Fatigue Damage in Layered Ceramic Structures

Abstract

Porcelain veneered restorations often chip and fracture from repeated occlusal loading, making fatigue studies relevant. Most fatigue studies are limited to uniaxial loading without sliding motion. We hypothesize that biaxial loading (contact-load-slide-liftoff, simulating a masticatory cycle) as compared to uniaxial loading accelerates the fatigue of layered ceramics. Monolithic glass plates were epoxy joined to polycarbonate substrates as a transparent model for an allceramic crown on dentin. Uniaxial and biaxial cyclic contact was applied through a hard sphere in water with a mouth-motion machine. The uniaxial (contact-load-hold-liftoff) and traditional Rratio fatigue (indenter never leaves the specimen surface) produced a similar lifespan, while biaxial fatigue was more severe. The accelerated crack growth rate in biaxial fatigue is attributed to enhanced tensile stresses at the trailing edges of a moving indenter. Fracture mechanics descriptions for damage evolution in brittle materials loaded repeatedly with a sliding sphere are provided. Clinical relevance is addressed.

Reliability of Reduced-thickness and Thinly Veneered Lithium Disilicate Crowns

“…They noted a 40% decrease in load to cone cracking with use of the carbide as opposed to the glass indenter. With mouth-motion testing in water, far fewer cycles are required to initiate partial cone cracking as compared with uni-axial loading (Kim et al, 2007). Glass on porcelain fatigue-testing leads to very high friction forces, promoting partial cone cracking.…”

Performance of Dental Ceramics: Challenges for Improvements

“…These "partial cone" cracks initiate and propagate at orders of magnitude fewer cycles than without the sliding component at similar loads (Kim et al, 2007;Kim et al, 2008). These hydraulically and friction-assisted partial cone cracks develop and, with continued subcritical loading in water, propagate (Bhowmick et al, 2007) (Fig.…”

Studies on mechanical strength, thermal expansion of layering porcelains to alumina and zirconia ceramic core materials

“…Due to its optimal esthetics, allceramic crowns have become highly appreciated in clinical application. High-strength ceramic core materials,whichwerefabricatedfrommaterialssuch as leucite 1) , lithium disilicate 2,3) , diopside 4) , alumina 5) , and zirconia [6][7][8][9][10][11][12][13][14][15] , are multi-veneered with more translucent feldspathic porcelain to improve esthetics. In this study, this type of porcelain is calledlayeringporcelain.…”