Influence of alveolar bone height on the biomechanical behavior of roots restored with custom-made posts-and-cores.

Abstract

This study evaluated the influence of alveolar bone height and post type on compressive force resistance, fracture pattern, and stress distribution in endodontically treated teeth. Bovine roots were endodontically treated and divided into eight groups (n=10) according to alveolar bone height (normal alveolar bone and alveolar bone loss - 2 and 5 mm from the margin of the crown, respectively) and post type (prefabricated glass fiber post, anatomic glass fiber post, customized milled glass fiber post-and-core and customized milled polyetheretherketone (PEEK) post-and-core). Mechanical fatigue was simulated (300.000 cycles/50 N/1.2Hz). Compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α=0.05). Fracture patterns were described as percentages. Stress distribution was analyzed by finite element analysis. Significant diferences were found for alveolar bone height (P < 0.0001): normal alveolar bone groups showed higher mean values of compression force resistance compared to alveolar bone loss groups, while no significant differences were found for post type (P=0.4551), and there was no double interaction between them (P=0.5837). Reparable fractures were more predominant in normal alveolar bone groups, especially in the milled glass fiber and PEEK post-and-core groups. Stress distribution was similar in groups with prefabricated glass fiber posts and milled PEEK posts-and-cores, and the alveolar bone loss condition significantly increased stress concentration and strain values, mainly on apical dentin. Alveolar bone loss due to physiological aging and/or periodontal disease may lead to increased risk of restored tooth failure, although milled glass fiber and PEEK posts-and-cores provide more reparable fractures. Custom-made glass fiber and PEEK post-and-cores are interesting options, since they enable clinicians to work with a single-body post-and-core system that avoid several materials interfaces and fits well in the root canal provided promising results to improve the failure behavior of restored roots, as they offer more reparable fractures even in situations of alveolar bone loss.