Biomechanical and weibull-based evaluation of bioceramic root filling and coronal restoration designs in apically resorbed premolars.

OBJECTIVES: This study aimed to evaluate the effects of different root canal filling strategies and coronal restoration types on the biomechanical behavior of mandibular premolars with simulated apical external root resorption using three-dimensional finite element analysis (FEA) combined with a two-parameter Weibull-based fracture probability assessment. MATERIALS AND METHODS: MTA plug + gutta-percha + composite core and ceramic crown (MTA/GP/CC), MTA full-canal obturation + composite core and ceramic crown (MTA/CC), MTA plug + gutta-percha + hybrid-ceramic endocrown (MTA/GP/ECR), MTA full-canal obturation + hybrid-ceramic endocrown (MTA/ECR), Biodentine plug + gutta-percha + composite core and ceramic crown (B/GP/CC), Biodentine full-canal obturation + composite core and ceramic crown (B/CC), Biodentine plug + gutta-percha + hybrid-ceramic endocrown (B/GP/ECR), Biodentine full-canal obturation + hybrid-ceramic endocrown (B/ECR), and an intact tooth (IT). A 300 N oblique load was simulated for all models. RESULTS: FEA showed that the highest tensile stress in coronal restorations occurred in the MTA/GP/ECR model, whereas the lowest values were found in the MTA/ECR and B/ECR models. Within root dentin, maximum tensile stress was highest in the B/GP/CC model (0.683 MPa) and lowest in the MTA/ECR configuration (0.534 MPa). At 300 N, Weibull-based system fracture probabilities ranged from 0.0180% to 0.0192% for full-coverage crown (CC) designs and from 0.0157% to 0.0167% for ECR designs. For matched root-filling strategies, ECR configurations showed approximately 13-14% lower relative system fracture probabilities than the corresponding CC configurations. CONCLUSIONS: Complete bioceramic obturation combined with a hybrid-ceramic endocrown (ECR) showed a favorable biomechanical profile and the lowest relative Weibull-based system fracture probabilities among the evaluated configurations. CLINICAL RELEVANCE: Within this idealized FEA-Weibull framework, ECR restorations combined with full-canal bioceramic obturation showed modestly lower relative system fracture probabilities than matched full-coverage crown configurations. The probabilistic response was dominated by root dentin rather than by direct fracture contributions from the restorative materials.