An analysis of failure mode of teeth restored with fiber-reinforced posts under the condition of bony resorption

Lee, Byung Woo; Yi, Yang Jin; Cho, Lee Ra; Park, Chan Jin

Abstract

STATEMENT OF PROBLEM: Fiber-reinforced posts have lower modulus of elasticity than titanium post or cast post-core. With this similar elasticity to that of dentin, fiber-reinforced posts have been known to have a tendency to reduce the risk of root fracture. However, there were few studies on the teeth restored with fiber-reinforced posts under the condition of reduced periodontal support. PURPOSE: The purpose of this study was to evaluate the fracture strength and failure mode of endodontically treated teeth restored with fiber-reinforced posts and titanium posts under the condition of reduced periodontal support. MATERIAL AND METHOD: Extracted human maxillary incisor roots were divided into 3 groups (group 1 : carbon fiber post, group 2 : glass fiber post, and group 3 : titanium alloy post). After coronectomy and endodontic treatment, teeth were restored with each post systems and resin core according to the manufacturer's recommendation. Then, teeth with simulated periodontal ligament were embedded in the acrylic resin blocks at the level of 4 mm below the cemento-enamel junction. Each specimen was exposed to 105 load cycles with average 30 N force in 36.5 degrees C water using a computer-controlled chewing simulator. Loads were applied at 45.angle to the long axis of the teeth. After cyclic loading, teeth were subjected to a compressive load until failure at a crosshead speed of 0.5 mm/min. Fracture strength (N) and failure mode were examined. The fracture strength was analyzed with one-way ANOVA and the Sch ffe adjustment at the 95% significance level. RESULTS AND CONCLUSION: The results were as follows. 1. There was no statistically significant difference in the mean fracture strength among the groups ( P>0.05). 2. Carbon fiber post and glass fiber post group showed less root fracture tendency than control group. 3. All specimens with root fractures showed fracture lines above the level of acrylic resin block, except for only one specimen in group 3.