Abstract:
Background and rationale:Endodontically treated teeth with less remaining tooth structure of ferrule or a large post space may affect the longevity of restoration Objective:Th objective of this study is to evaluate the effect of ferrule and fiber reinforced composite post diameter (post fit to space or smaller than post space) on fracture resistance and failure mode in restored endodontically treated teeth. Material and methods:Thirty two extracted human maxillary central incisors were randomly divided into 4 experimental groups; 1: ferrule + post fit, group 2: ferrule + smaller post, group 3: no ferrule + post fit and, group 4: no ferrule + smaller post. Root canal treatment was performed and post space was prepared using DT light drill no.2. In groups 1 and 3, the teeth were restored using DT light post no.2, while in groups 2 and 4, DT light post no.1 was used. The posts were cemented with resin cement (Panavia F 2.0), then core build-up was fabricated with resin composite (Tetric N ceram). Chamfer preparation was performed around the teeth. Ni-Cr crowns were fabricated and cemented onto the core with resin cement (Panavia F 2.0). The restored teeth were embedded in self-cured acrylic resin blocks with a simulated PDL. The specimens were loaded on a universal testing machine with a crosshead speed of 1 mm/min on the palatal surface at an angle of 135๐ to the long axis of the tooth until failure occurred. Results: The fracture resistance of groups 1, 2, 3 and 4 were 1474.7 ± 285.5 N, 1339.4 ± 120.6 N, 811.7 ± 155.7 N, and 668.5 ± 170.2 N, respectively. Two-way ANOVA and Tukey HSD post-hoc analysis revealed the fracture resistance of groups 1 and 2 were significantly higher than group 3 and 4 (p<0.05). No significant differences were found between groups 1 and 2 and between groups 3 and 4. Conclusion: Preparation of 2 mm ferrule significantly increased the fracture resistance of endodontically treated teeth restored with FRC post. The use of posts with smaller diameter did not significantly decrease the fracture resistance compared to posts properly fit to the canal
