Stress Distribution and failure probability of all ceramic crowns in graded and bioinspired zirconia

Abstract

The present study will evaluate the failure probability of crowns with or without glass infiltration in the zirconia structure, with conventional or bioinspired structures, using Weibull analysis after fatigue. The stress distribution in the crown by the Maximum Principal Stress criteria will be also assessed. One hundred anatomical preparations will be used, and divided into 4 groups: Traditional: infrastructure in zirconia and porcelain cover; Graded: infrastructure in glass-infiltrated zirconia and porcelain cover; Bioinspired: infrastructure in porcelain and zirconia cover and Bioinspired Graded: infrastructure in porcelain and glass-infiltrated zirconia cover. The fatigue load will be 100N. Specimens will then be mechanically cycled in a simulator of chewing cycles (BioPdi sliding), where an applicator tip will apply 2.106 cycles at 3 Hz. Every 200,000 cycles, the machine will be stopped and the crowns will be assessed for the presence of failures in a stereomicroscope (DiscoveryV20, Carl Zeiss, LLC, USA). If samples do not show any failure (cracks, chipping, debonding between porcelain and zirconia and catastrophic failures), the fatigue test will continue until they fail or until the test is finished. Specimens that do not fail will be considered "suspended" in the analysis, Results from this evaluation will be subjected to reliability analysis with the Weibull method, with bilateral confidence interval of 95%. Also there will be a Finite Element Analysis to assess the stress distribution in the crown by the Maximum Principal Stress.