In Vitro Evaluation of Root Fracture Strength in Teeth Restored with Different Endodontic Post-Core Systems

Background: This study evaluated the effects of post-core restorations on root fractures with extensive loss of coronal tooth structure in terms of manufacturing method and material selection. Methods: Seventy-two human maxillary central incisors were decoronated to a length of 15 mm, and a 2-mm ferrule was prepared. Following root canal treatment, post spaces were created to a depth of 10 mm using a 1.3-mm-diameter drill. The specimens were then randomly divided into 6 groups: (1) fiber post, (2) fiber post-core, (3) metal post, (4) metal post-core, (5) polyether ether ketone (PEEK) post, and (6) PEEK post-core (n = 12). All posts or post-cores were luted using a self-adhesive dual-cure resin cement. The full-coverage crowns were fabricated and cemented using resin cement. The fracture resistance was assessed using a universal testing machine, and the failure modes were analyzed using a stereomicroscope. Statistical analysis was performed using the Kruskal–Wallis test for overall comparisons and Dunn’s test for pairwise comparisons (P < .05). Results: No statistically significant differences were found in fracture resistance between the groups (P < .05). The highest mean fracture strength was observed in the metal post-core group. In contrast, the fiber posts group exhibited the lowest fracture strength. Analysis of the failure patterns indicated a higher incidence of repairable fractures in the fiber and PEEK groups. Conclusion: The PEEK group exhibited comparable fracture strengths; however, post-debonding was the most frequently observed type of failure in the PEEK post-core group.