Reinforcement of Simulated Immature Permanent Teeth after Mineral Trioxide Aggregate Apexification

Objectives: The objectives of this study were to compare the fracture resistance of simulated human immature teeth that have undergone mineral trioxide aggregate (MTA) apexification and have been root filled with fiber post, composite resin, MTA, orguttapercha. Methods: Fifty-six human permanent maxillary incisors were selected. Ten teeth received no treatment (intact teeth group). The root canals of 46 teeth were prepared to an internal diameter of 1.75 mm. Six teeth were used as simulated immature teeth group. The remaining teeth received MTA apexification and were divided into 4 groups: MTA, fiber post, composite resin, and gutta-percha groups. The root canals of each group were filled with each test material. All teeth were thermocycled and received cyclic loading before compression testing by an Instron universal testing machine. The load to fracture was recorded. Data were subjected to statistical analysis by using one-way analysis of variance and Tukey multiple comparison test. Results: All teeth fractured at the cervical area of the root. The mean load to fracture of the intact tooth, MTA, fiber post, composite resin, gutta-percha, and the simulated immature tooth groups was 1988 N, 1921 N, 1691 N, 1623 N, 1476 N, and 962 N, respectively. Statistically, load to fracture of the simulated immature tooth group was significantly lower than in the intact tooth, MTA, fiber post, and composite resin groups but was not significantly different from the gutta-percha group. Conclusions: Within the limit of this study, after MTA apexification, intraradicular reinforcement with MTA, fiber post, or composite resin increased the fracture resistance of simulated immature teeth.