Comparative Evaluation of Application of Universal Bonding on the Microtensile Bond Strength of Light Cure and Dual Cure Composites Bonded to Dentin.

Objectives: There is limited knowledge on the efficacy of universal adhesives when used in different etching modes. The aim of this study was to evaluate the microtensile bond strength (µTBS) to dentin using universal adhesives with light-cure and dual-cure composites. Materials and Methods: In this in vitro experimental study, the occlusal third of 60 caries-free human molars were removed and the exposed surfaces were treated and allocated to 10 groups (N=6). Two different bonding agents (Single Bond Universal, G-Premio) were used to bond 2 different composite resins (Z250 light-cure and CoreFlo DC dual-cure) to dentin, using etch-and-rinse (E&R) and self-etch (SE) modes. Single Bond 2 was applied in E&R mode on wet dentin to serve as control. The specimens were sectioned into 1×1 mm2 sticks with a precision saw. A microtensile testing machine was used to measure the µTBS of the specimens with a crosshead speed of 0.5 mm/min. Data were analyzed using three-way ANOVA and Bonferroni post-hoc test (α=0.05). Results: The Single Bond Universal group in SE mode with light-cure composite yielded the highest (39.24MPa), and the G-Premio SE group with dual-cure composite produced the lowest (13.65MPa) mean µTBS (P<0.05). The dominant failure mode was adhesive, in all groups. Conclusion: The bonding agent had a significant effect on µTBS of composite to dentin, but different composites and different etching modes were not significantly different in this respect.