CAD/CAM Milled Glass Fiber Posts: Adaptation and Mechanical Behavior in Flared Root Canals

This study aimed to evaluate the cementation and mechanical behavior of flared root canals restored with CAD/CAM milled glass fiber post-and-core systems. Sixty-six endodontically treated human canines with a flared root canal were divided into three different groups according to the type of post: G(PF) received prefabricated posts; GREL received relined glass fiber posts, and G(MILLED) received CAD/CAM milled glass fiber posts. Cementation was performed with self-adhesive resin cement. The samples were submitted to x-ray microcomputed tomography analysis for the analysis of voids and gaps. The roots were sectioned and submitted to the push-out bond strength test. The load-to-fracture was evaluated in post-and-core systems. G(MILLED) presented lower void and lower gap volumes when compared to G(PF) and G(REL). On the load-to-fracture test, G(REL) presented statistically significant higher values than G(MILLED). G(PF) values had no statistically significant difference from the two other groups. On the push-out bond strength test, GPF presented statistically significant lower values when compared to G(REL) and G(MILLED). The most common failure pattern was between dentin and cement in all groups. CAD/CAM milled glass fiber post-andcore systems presented an enhanced adaptation of glass fiber posts to flared root canal systems. Their results were comparable to relined posts in bond strength, while load-to-fracture-results for G(MILLED) were lower than those for G(PF).