This study aims to examine the use of universal adhesives with dual-cure activators to evaluate their effect on the adhesion of light-cured and dual-cured composites to dentin. Ninety caries-free human third molar teeth were randomly allocated into three groups. The groups (N=30) were classified according to the adhesive agents used: Prime Bond Universal (PB), Clearfil Universal Bond Quick (CU), and G Premio Bond (GP).

On the dentin sample surfaces, PB, CU, and GP were utilized in light-curing mode (LC), dual-curing mode (DC), and self-curing mode (SC). Clearfil SE Bond (CSE) was used as the control (n=10). Shear bond strength was measured using a universal testing machine. The collected data were subjected to analysis of variance (ANOVA) and Tukey's HSD tests (p<0.05). Statistically significant variances were observed among the different bonding agents, composite materials, and polymerization modes. The utilization of universal adhesive systems in combination with dual-cure activators resulted in a significant decrease in the bond strength of light-cured composites to dentin (p<0.05).

Adhesive type failure was the most common both adhesives agents and curing modes. The dual-cure activators were found to be inadequately effective in mitigating the incompatibility issues between the dual-cure composite and the universal adhesives.