Comparative Evaluation of Push-Out Bond Strength Between CAD/CAM-Milled and Anatomically Customized Fiber Posts: An In Vitro Study.

OBJECTIVES: This in vitro study evaluated the push-out bond strength of two types of intraradicular fiber posts: conventional customized anatomical posts and milled fiber posts, cemented with two different strategies. METHODS AND MATERIALS: Sixty bovine incisors with roots sectioned at the cementoenamel junction and standardized to a length of 15 mm were endodontically treated. All specimens were randomly assigned to four groups (n = 15) based on post type and cementation strategy; customized anatomical post cemented with self-adhesive resin cement (RelyX U200, G1); customized anatomical post cemented with dual-cure resin cement (RelyX Universal resin cement, G2); milled fiber post cemented with self-adhesive resin cement (RelyX U200 resin cement, G3); and milled fiber post cemented with dual-cure resin cement (RelyX Universal resin cement, G4). Push-out bond strength measurements (MPa) were obtained from three root sections (cervical, middle, and apical) using a universal testing machine at a speed of 0.5 mm/min until failure. The interfaces and failure modes were analyzed using scanning electron microscopy (SEM). Statistical analysis included three-way analysis of variance (ANOVA) and Tukey's post hoc test to compare groups and root sections. RESULTS: CAD/CAM-milled posts (G3 and G4) exhibited significantly higher bond strength (mean PBS = 13.1 ± 3.9 MPa) compared to customized anatomical posts (G1 and G2) (mean PBS = 9.7 ± 2.8 MPa) (p  < 0.01). Bond strength varied significantly across root thirds (p = 0.034), with the apical and middle thirds demonstrating higher values than the cervical third. No significant difference in bond strength was observed between the two cementation strategies (p = 0.27). CONCLUSION: CAD/CAM-milled fiber posts demonstrated higher push-out bond strength than customized anatomical posts, regardless of the cementation strategy. However, these groups also exhibited a greater frequency of catastrophic failures, indicating that higher bond strength should not be interpreted as overall clinical superiority. Additional studies are needed to determine the clinical significance of these findings.