Fracture Resistance of the Crown Retained By Milled Computer-Aided Design-Computer-Aided Manufacturing Unidirectional Fiber-Reinforced Composite Post

Abstract

The study aimed to compare the fracture resistance of the crown retained by milled computer - aided design - computer - aided manufacturing ( CAD - CAM) unidirectional fiber - reinforced composite posts across two distinct designs with a commercial post. Twenty-one extracted permanent mandibular premolars were endodontically treated and randomly divided into three groups of seven specimens. The first group received one-piece CAD-CAM unidirectional fiber-reinforced composite posts and cores (MPC). The second group received CAD-CAM milled posts in combination with composite cores (MP). The control group used commercial fiber posts (RelyXTM fiber post). After cementing the post, core, and crown, each specimen was subjected to a compressive load at an angle of 60 degrees to the long axis of the tooth at a speed of 1 mm/min until fracture. The fracture characteristics were observed in two aspects: external crack position and internal debonded position. The fracture resistance of the MPC group (2047.5 ± 238.6 N) was significantly higher than the MP (1625.6 ± 211.1 N) and control group (1651.1 ± 261.7 N). Only internal debonded positions found differ between groups, not external crack positions. One-piece fiber-reinforced composite posts showed superior fracture resistance and may be used as an alternative treatment for post-restored teeth.