Comparative evaluation of preobturation dentin sealing and different irrigation activation methods on push out bond strength of fiber post in root canals obturated using apical and conventional coating techniques: An in vitro study

Aim: The aim of this study was to evaluate and compare the effect of preobturation dentin sealing (PODS) and post space conditioning methods on the push-out bond strength (PBS) of fiber posts luted in root canals obturated using bioceramic sealer (BCS). Methods: Sixty-six single-rooted extracted human teeth were instrumented and obturated with BCS using three different protocols: PODS, conventional gutta-percha (GP) coating (conventional coating obturation [CCO]), and apical GP coating (apical coating [AC]). Following 24 h of storage at 37°C in 100% humidity, post space preparation was carried out, followed by irrigation activation using either ultrasonic method (US) or diode laser (DL), to facilitate residue sealer elimination. Fiber posts were bonded with a self-adhesive resin cement. Roots were then sectioned into coronal, middle, and apical thirds, and PBS was evaluated. Data were assessed for probability distribution using Kolmogorov–Smirnov test. Intergroup comparisons were performed using one-way analysis of variance or Kruskal–Wallis test. P < 0.05 was considered statistically significant. Results: Significant differences were observed among the groups and at different root levels ( P < 0.05). PODS + US demonstrated the highest PBS, particularly in the coronal third (14.35 ± 3.12 MPa). In the middle and apical thirds, PODS + US activation and AC + US activation showed comparable bond strength values ( P > 0.05). CCO exhibited the lowest bond strength across all root levels. Overall, ultrasonic activation consistently resulted in higher bond strength compared to DL activation. Conclusions: PODS with ultrasonic activation enhances post space cleanliness and optimizes resin-based post adhesion, suggesting a clinically favorable strategy for postendodontic restorations.