Effect of final irrigants on bond strength and penetrability of a next-generation calcium silicate cement-based sealer in retreated root canals

Purpose This study evaluated the effect of four final irrigants on the bond strength and penetrability of a calcium silicate-based sealer during nonsurgical endodontic retreatment. Materials and methods Forty-eight maxillary canines were randomly assigned to four groups (n = 12) according to the final irrigant used during retreatment: 17% EDTA, 10% hydrochloric acid (HCl), Triton™, or Granudacyn™. All specimens underwent standardized primary treatment with the Reciproc® system (R25), 2.5% sodium hypochlorite, 17% EDTA irrigation, and single-cone obturation with Bio-C Sealer ion+. After thermocycling (10,000 cycles, 5°C/55°C), root fillings were removed with the Reciproc® system (R50), and the assigned final irrigation protocols were applied before retreatment obturation with the same sealer. Each tooth was sectioned into 9 slices (1.0 ± 0.2 mm) for push-out bond strength testing, failure mode analysis, confocal laser microscopy, and fluorescence microscopy. Results EDTA (0.86 ± 0.48 MPa) and Granudacyn™ (0.99 ± 0.33 MPa) produced significantly higher bond strength than HCl (0.41 ± 0.14 MPa) and Triton™ (0.33 ± 0.13 MPa). Adhesive failures predominated in all groups. Confocal and fluorescence analyses showed a more continuous adhesive interface and more homogeneous cement penetrability in the EDTA and Granudacyn™ groups, whereas Triton™ showed greater intratubular penetration. Conclusion Under these in vitro conditions, 17% EDTA and Granudacyn™ improved bond strength and interfacial quality, whereas Triton™ promoted greater intratubular penetration but lower bond strength. These findings should be interpreted cautiously because clinical healing variables were not evaluated.