Resin composite bond strength and durability of two-bottle universal adhesive system to enamel and dentin

Abstract

Background. Despite the advantages of one-step universal adhesive systems, there are concerns about the long-term durability of their adhesive layer. Due to introducing two-bottle universal adhesive systems, this study aimed to evaluate the bond durability of two-bottle universal adhesive system to enamel and dentin. Materials and Methods. In this in vitro study, 32 extracted sound human third molar teeth were selected. To prepare the enamel sample, the outer layer was removed from the buccal or lingual surface of each tooth. For the dentin sample, the occlusal enamel was cut perpendicular to the longitudinal axis. The samples in each dentin and enamel group were randomly divided into four groups based on the adhesive type and etching strategy: G-premio Bond: GP. ER/SE, G2-Bond Universal: G2. ER/SE. After applying the adhesive, the entire surface of the substrate was restored by resin composite and light cured. After sectioning the samples into 1 mm2 sticks, they were randomly divided into two subgroups. In one group, specimens were subjected to thermal cycles, while those in the other group were stored in a 10% NaOCl solution for 3 hours to simulate artificial aging. The microtensile bond strength of the samples was measured using a universal testing machine, and their failure modes were determined. Data were analyzed using two-way ANOVA, Games-well and Sidak post hoc tests(P < 0.05). Results. Microtensile bond strength values after artificial aging were significantly lower than before the aging process(P<0.001). In enamel, μTBS values of the aging group for GP_SE were lower than those for G2_SE and G2_ER, while the values in dentin for GP_ER were lower than those for G2_SE and G2_ER. The effect of dental substrate on μTBS at 24 hours was significant (p= 0.043). Relatively similar failure modes were observed in groups. Conclusion. As a result of aging, the bond strength of all adhesive systems decreased. This study showed the superior performance of G2-bond over G-premio.