Effect of Gutta-Percha Removal Methods on Fiber-Post Bond Strength

<b>Objectives:</b> This study evaluated the effect of three root canal filling material (RCFM) removal techniques-mechanical, thermo-mechanical, and chemico-mechanical-on the micro push-out bond strength of fiber posts to root dentin in endodontically treated teeth. <b>Materials and Methods:</b> Forty-five single-rooted human premolars were endodontically treated and randomly allocated into three groups (<i>n</i> = 15) according to the RCFM removal technique used during post-space preparation: mechanical, thermo-mechanical, or chemico-mechanical. Fiber posts were luted using a dual-cure resin cement. Roots were embedded in resin and sectioned into coronal, middle, and apical thirds. Micro push-out bond strength was measured using a universal testing machine. Failure modes were examined under a stereomicroscope and validated using scanning electron microscopy. Statistical analysis used two-way ANOVA and Chi-square tests (α = 0.05). <b>Results:</b> Both the thermo-mechanical and mechanical groups showed significantly higher bond strength values than the chemico-mechanical group (<i>p</i> < 0.001). Across all groups, the coronal third recorded the highest bond strength, while the apical third presented the lowest values (<i>p</i> < 0.001). Adhesive failure at the dentin-cement interface was the most frequent failure mode. <b>Conclusions:</b> The gutta-percha removal technique and the root canal region significantly influence fiber-post bond strength. Solvent-based chemico-mechanical methods may adversely affect adhesion quality. <b>Clinical Relevance:</b> Thermo-mechanical and mechanical removal techniques may provide more reliable post retention during retreatment procedures, improving adhesion and reducing the risk of post debonding in daily practice.