Abstract

Purpose: This study evaluated the effect of dimethyl sulfoxide (DMSO) pretreatment on the microtensile bond strength (mu TBS) and adhesive interface characteristics of universal adhesives systems applied in etch-and-rinse mode to endodontically modified dentin irrigated with calcium hypochlorite. Materials and methods: For mu TBS analysis, 240 bovine dentin specimens were divided into eight experimental groups according to the adhesive system used, DMSO pretreatment or not, and the evaluation period (24 h, 6 months, and 12 months) (n = 10). Failure modes and adhesive interface characteristics were also analyzed. mu TBS data were analyzed using two-way ANOVA and Tukey tests, and adhesive interface scores were analyzed using Kruskal-Wallis and Dunn tests (alpha = 0.05). Results: DMSO pretreatment resulted in significantly higher bond strength after 12 months compared with non-treated groups, while no significant differences were observed among evaluation periods for DMSO-treated specimens. In contrast, specimens bonded without DMSO exhibited a significant reduction in bond strength after aging. Failure mode analysis revealed a higher incidence of cohesive failures in DMSO-pretreated groups, particularly after long-term storage. Adhesive interface analysis showed increased resin tag formation and greater interfacial continuity in DMSO-treated dentin. Conclusion: These findings indicate that DMSO pretreatment improves the long-term stability of resin-dentin bonds and promotes more favorable interfacial characteristics in dentin previously exposed to calcium hypo-chlorite. DMSO may therefore represent a promising strategy to enhance bonding durability in endodontically modified dentin.