Reinforcing Effect of Intraradicular Filling Materials in Simulated Immature Mandibular Premolars with Mineral Trioxide Aggregate Apical Barrier: A Weibull Analysis

Abstract

Introduction: Incomplete root formation following pulp necrosis requires mineral trioxide aggregate (MTA) apexification. Although effective, this treatment does not increase the root thickness, necessitating additional reinforcement. This study aimed to evaluate the fracture resistance of simulated immature mandibular premolars apexified with MTA and reinforced with various materials using Weibull analysis. Methods: Ninety human mandibular first premolars were prepared to simulate immature teeth. After MTA apexification, teeth were divided into six groups: negative control (intact teeth), positive control (untreated apexified teeth), gutta-percha (GP) with AH Plus, GP with Bioceramic sealer, core, and fiber post/core. The teeth underwent thermocycling, periodontal ligament simulation, and fracture testing. Results: Negative and positive controls exhibited the highest and lowest fracture resistance, respectively. Core and fiber post/core had hazard ratios of 4.79 and 6.23, respectively, outperforming GP with AH Plus and GP with Bioceramic sealer (hazard ratios: 14.23 and 17.22, respectively). Most fractures occurred in the coronal third. Conclusions: Intraradicular reinforcement materials (fiber post/core and core) provided greater support to MTA-apexified roots than conventional root filling materials (GP/AH Plus and GP/Bioceramic sealer).