ABSTRACT
<p><b>OBJECTIVE</b>To study mechanical and cyclic fatigue behavior of IPS Empress2 under cyclic loading, and to establish guidelines for the use and design of all-ceramic crowns.</p><p><b>METHODS</b>A 3-D finit element method model of tooth and crown were established. The strength and lifetime of all-ceramic crowns under cyclic loading in centric occlusion were investigated using computational techniques of the Abaqus and MSC Fatigue software.</p><p><b>RESULTS</b>Most of the fatigue and fracture of all-ceramic crown occurred within the veneering material at cervical marginal of the crown. The number of loading cycles before failure occurred varied within specified limits 2,506,109-6,950,243. The lifetime of the crown decreased significantly as loading increased and decreased gradually as loading time increased as well.</p><p><b>CONCLUSIONS</b>The mechanical and fatigue behavior of ceramic materials and restorations need to be improved before clinical use in order to guarantee clinical long-term success of all-ceramic crown. properly in order to increase the longevity of all-ceramic crowns.</p>
Subject(s)
Dental Porcelain , Denture, Partial, Fixed , Finite Element Analysis , Materials TestingABSTRACT
<p><b>OBJECTIVE</b>To study the residual stresses of ceramic-metal bond at viscoelastic and elastic phases during cooling of porcelain-fused-to-metal in order to precisely calculate the ceramic-metal bond strength and improve the restorations.</p><p><b>METHODS</b>The finite element model was set up according the crack initiation test (three-point flexure bond test) based on ISO Standard, elements of viscoelastic and themal-displacement were used to part the model. The result at viscoelastic phases was used as initiation condition of elastic phases to add up.</p><p><b>RESULTS</b>The compressive stress was caused by metal during cooling occurred in the ceramic. The shear stress induced by loading was offset by thermal shear stress. Load tensile stress and the thermal compressive stress vertical of interface concentrated at the end of the bond interface, but the tensile was greatly higher.</p><p><b>CONCLUSION</b>The residual stress is very important to metal-ceramic restorations, and the viscoelastic behavior of porcelain greatly influences it. If the metal and ceramic are compatible,the components stresses of the residual stresses may benefit to ceramic-metal bond, and can be taken as a part of bond stresses.</p>