Comparative Analysis of Bond Strength in Endodontic Access: Immediate Endodontic Sealing Versus Delayed Endodontic Sealing.

INTRODUCTION: Coronal leakage and restoration failure remain significant contributors to the failure of endodontic treatments. This study aimed to evaluate the influence of different adhesive systems and treatment protocols, specifically immediate endodontic sealing (IES) and delayed endodontic sealing (DES), on bond strength. MATERIALS AND METHODS: Sixty extracted human mandibular third molars were prepared to expose the pulp chamber dentin and randomly assigned to six groups according to the adhesive systems (OptiBond™ FL (Kerr Dental, California, United States) or Single Bond Universal adhesive (Solventum Corporation, Eagan, Minnesota, United States)) and the treatment protocols (control, IES, and DES). Sodium hypochlorite irrigation was performed based on experimental protocols. Following composite restoration, specimens were thermocycled for artificial aging and subsequently sectioned into beams for microtensile bond strength (µTBS) testing (10 teeth per group). Data were analyzed using two-way ANOVA and Kruskal-Wallis with Dunn's post hoc test (α = 0.05). RESULTS: A significant interaction between adhesive system and treatment protocol was identified (p < 0.05). With OptiBond FL, IES produced significantly higher µTBS values than DES (52.85 ± 7.22 MPa vs 40.98 ± 5.76 MPa; p < 0.05) and was comparable to the control group (57.59 ± 7.18 MPa; p > 0.05). The OptiBond FL group demonstrated significantly higher bond strength than the Single Bond Universal group under all conditions (p < 0.05), whereas the IES-Single Bond Universal adhesive (34.43 ± 5.97 MPa) and DES-Single Bond Universal adhesive (30.27 ± 5.49 MPa) groups showed significantly lower µTBS values than the control-Single Bond Universal adhesive (41.12 ± 4.85 MPa; p < 0.05). Failure mode analysis revealed predominantly adhesive failures in all groups. CONCLUSIONS: Within the limitations of the in vitro study, IES with OptiBond FL resulted in higher µTBS than DES.