Effect of six-month water storage on microtensile bond strength of etch and rinse and self-etch adhesive systems to dentin

Background: Despite the durable enamel bonding, durability of dentin bonding is under question. However, some self-etch adhesives have been reported to perform as good as etch & rinse adhesive and can resist more against degradative mechanisms. Objective: To evaluate the dentin bond strength durability using etch & rinse and self-etch approaches over 1 day and 6 months water storage. Methods: This was an experimental study conducted at Shahed Dental School (Tehran, Iran) in 2010. A total of 32 extracted human third molar were sectioned to expose the superficial dentin and randomly distributed into four groups as: three-step etch & rinse adhesive (SBMP), two-step etch & rinse adhesive (SB), two-step self-etch adhesive (CSEB), and one-step self-etch adhesive (ABSE). A resin composite crown was incrementally built up. Microtensile specimens were fabricated and stored in distilled water containing 0.5% chloramine T and the tensile tested after 1 day and 6 months. The failure patterns of debonded specimens were recorded using stereomicroscopy. One-way ANOVA and Tamhan statistical tests were applied. Findings: The SB group attain ed the highest bond strength, in 1 day (27.42±3.67 Mpa) and 6 months (27.28±3.25 Mpa). The short-term bond strength of SBMP and CSEB groups were similar (P>0.05). A significant decrease in bond strength was observed for both ABSE and SBMP groups (P<0.05). No reduction in bond strength of SB and CSEB groups was found after 6 months. The ABSE group attained the lowest bond strength compared to other groups (1 day: 11.77±2.81 Mpa, 6 months: 9.33±1.71Mpa). The failure pattern of SBMP and ABSE groups was adhesive which increased over 6 months. The most frequent pattern of SB and CSEB groups was adhesive which was stable over time. Conclusion: Based on findings of the present study, the resistance of resin-dentin bonds to degradation is material-dependent. The mild two-step self-etch adhesive (CSEB) demonstrates similar short-term performance with SBMP, and remains stable against degradative mechanisms.