Finite element and Weibull analyses to estimate failure risks in the ceramic endocrown and classical crown for endodontically treated maxillary premolar

The present study evaluated the failure risks of an endodontically treated premolar with severely damaged coronal hard tissue and restored with either a computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic endocrown or a classical crown configuration. Two, three-dimensional finite element maxillary premolar models were designed with endodontic treatment and restored with either a chairside economic reconstruction of esthetic ceramic (CEREC) ceramic endocrown or a classical crown. The Weibull function was incorporated with finite element analysis to calculate the long-term failure probability relative to different load conditions. Additionally, an in vitro fatigue-load fracture experiment was performed to validate the numerical simulation results. The results indicated that the stress values on the dentin and luting cement for the endocrown restoration were lower than those for the crown configuration. Weibull analysis revealed that the individual failure probability in the endocrown dentin and luting cement diminished more than those for the crown restoration. While the overall failure probabilities for the endocrown and the classical crown were similar, fatigue fracture testing revealed that the endocrown restoration had higher fracture resistance than the classical crown configuration (1,446 vs. 1,163 MPa). This investigation implies that the endocrown can be considered as a conservative, aesthetic, and clinically feasible restorative approach for endodontically treated maxillary premolars.