Evaluation of failure risks in ceramic restorations for endodontically treated premolar with MOD preparation

Objectives: This study evaluated the risk of failure for an endodontically treated premolar with MOD preparation and three CEREC ceramic restoration configurations. Methods: Simulations were performed based on three 3D finite element (FE) models designed with CEREC ceramic inlay, endocrown and conventional crown restorations. Long-term failure probability in relation to varying load conditions was calculated by incorporating the Weibull function in FE analysis. Additionally, the final fracture strength and corresponding load value of the first acoustic emission (AE) activity in each specimen was recorded by performing in vitro AE analysis in CEREC restored teeth compressive testing. Results: Simulation results indicated that the stress values on the enamel, dentin and luting cement for endocrown restorations were the lowest ones among the corresponding values for inlay and conventional crown restorations. Weibull analysis indicated that failure probability was 95%, 2% and 2% for the inlay, endocrown and conventional crown restorations, respectively, for normal biting. AE analysis revealed that, although the significantly least load was required for the first AE activity for inlay configuration, the endocrown and conventional crowns did not significantly differ from each other. Significance: This in vitro study, i.e. numerical and AE analyses, suggest that endocrown and conventional crown restorations for endodontically treated premolars with MOD preparation present a similar longevity.