Iranian Endodontic Journal

Abstract

Introduction: Internal root resorption (IRR) creates irregular canal irregularities that complicate cleaning and obturation. This in vitro study evaluated the obturation quality of a bioactive root canal sealer (Bioactive RCS) using different filling techniques in simulated IRR cavities. Materials and Methods: Forty extracted mandibular premolars were prepared to size F3. Artificial IRR cavities were induced in the middle third via a sectioning method. Samples were randomized into four groups (n=10): Single Cone (SC), Bulk Fill (BF), Bulk Fill with Ultrasonic Activation (BF+UA), and Continuous Wave Compaction (CWC). Pre- and post-obturation Cone-Beam Computed Tomography (CBCT) scans were analyzed using 3D Slicer software to calculate the Percentage of Obturation Volume (POV). Statistical analysis was performed using one-way ANOVA and Tukey HSD tests (P<0.05). Results: No technique achieved complete 3D obturation. The CWC group demonstrated the highest total POV (94.15±1.63%), followed by SC (90.66±1.77%). Both CWC and SC resulted in significantly higher obturation volumes compared to BF+UA (85.07±2.30%) and BF (83.08±2.14%) (P=0.001). While CWC performed best across all root thirds, the SC technique showed stable POV consistency across coronal, middle, and apical sections. Ultrasonic activation significantly improved bulk fill performance compared to bulk fill alone, which yielded the lowest values, particularly in the apical third. Conclusion: Within the limitations of an in vitro hemispheric cavity model and CBCT-based volumetric analysis, CWC achieved the highest POV in teeth with simulated internal root resorption. The SC technique, combined with bioceramic sealer, produced stable/comparable POV values, representing a viable/effective alternative. Ultrasonic activation improved sealer distribution compared to passive bulk fill alone, which was the least effective method. However, POV measures immediate volumetric adaptation and does not directly confirm fluid‑tight sealing; clinical correlation and assessment of long‑term leakage resistance require further investigation.