Effect of thermocycling and water storage on bond longevity of two self-etch adhesives

Despite recent improvements in adhesive systems and their bond strength to enamel and dentin, the resin-tooth interface appears to be the weakest part of tooth-colored restorations; in addition, there are concerns regarding bond durability of self-etch adhesives (SEAs). This in vitro study investigated the bond durability of 2 such adhesives following thermocycling and water storage. Forty-eight intact human third molars were sectioned mesiodistally and mounted in acrylic resin so that buccal and lingual surfaces were positioned horizontally. All enamel and dentin surfaces were ground flat and polished on silicon carbide papers. Samples were separated into 2 groups (n = 24). A 1-step SEA was applied to one group, while a 2-step SEA was applied to the other, according to manufacturers' instructions. Half of the specimens in each group underwent shear bond strength (SBS) testing after 24 hours of incubation, while the other half were tested after 3000 thermal cycles and 6 months of water incubation. SBS data were analyzed using 2-way ANOVA, 1-way ANOVA, and a post hoc Tukey test at a significance level of 0.05. Under the limitations of the present study, the 2-step SEA demonstrated higher baselines and aged bond strength to dental tissues compared to the 1-step SEA; in addition, the enamel bond strength of the 2-step SEA improved after aging.