Fracture Resistance of Flared Teeth Restored with Fiber-Reinforced Composite Posts

Objectives: The aim of this in vitro study was to compare fracture resistance of root-reinforced anterior teeth by 3 different methods, with tooth-colored materials.

Methods: Forty sound maxillary human central incisors were randomly assigned to 4 groups (n=10). Tooth crowns were removed 2 mm incisal to the cemento-enamel junction (CEJ). After root canal therapy, flared canals were simulated. In the first, second, and third groups, flared canals were reinforced with resin composite (Clearfil DC Core Automix) (RCO), Reforpins (REF), and resin cement (Panavia F 2.0) (RCE), respectively. In the fourth (DEN) group, flared canals were not created. In all groups, fiber-reinforced composite (FRC) posts of the same size were cemented with resin cement (Panavia F 2.0). After post cementation and restoration of the crowns with a core build-up composite (Clearfil Photo Core), the roots of the teeth were embedded in acrylic resin blocks, 1 mm below the CEJ. The samples were loaded in an Instron testing machine, with a crosshead speed of 0.5 mm/min at a 45-degree angle to the long axis of the tooth on the palatal surface, until failure occurred. Data were analyzed by the Kruskal-Wallis, Mann-Whitney, and Chi-square tests (a = 0.05).

Results: Significant differences were found in fracture resistance in all of the groups (P < 0.05), with the exception of the RCO and REF groups. The least mean value, 230 (130) N, and the highest mean value, 830 (220) N, were shown in the fracture resistance of the RCE and DEN groups, respectively.

Conclusion: For internal reinforcement of weakened roots, Reforpin can be used as an alternative to resin composite.