Is fracture resistance of endodontically treated mandibular molars restored with indirect onlay composite restorations influenced by fiber post insertion?

OBJECTIVES: The aim of this study was to investigate the influence of post placement on fracture resistance of endodontically treated mandibular molars restored with adhesive overlay restorations. METHODS: Endodontically treated human molars with two- and one-wall cavities either underwent or did not undergo fiber post insertion within composite build-up before cementation of indirect composite onlay restorations. The specimens were thermocycled, exposed to cyclic loading, and submitted to the static fracture resistance test. Fracture loads and mode of failure were evaluated. RESULTS: Statistical analysis revealed that specimens with fiber posts demonstrated similar failure loads (p=0.065) but more favorable fracture patterns compared with specimens without fiber posts. No difference was found between two- and one-wall cavities. CONCLUSIONS: Within the limitations of this study, the insertion of fiber posts did not improve support under indirect composite overlays. Clinical Significance: When restoring heavily broken down endodontically treated mandibular molars with an indirect overlay composite restoration, the fiber post inserted within the composite build-up do not provide any increase in fracture resistance.