Effect of polymerization mode on dentin bond strength of universal adhesives: influence of aging and application strategy.

OBJECTIVES: This study evaluated the effect of polymerization mode on dentin bond strength of universal adhesives applied using etch-and-rinse (ER) and self-etch (SE) strategies, before and after thermocycling. METHOD AND MATERIALS: A total of 120 human molar dentin specimens were prepared and assigned to 12 groups (n = 10) according to adhesive polymerization type (light-cured, chemically cured, and dual-cured), application mode (ER and SE), and storage condition (24 hours or thermocycled). After adhesive application and composite build-up, half of the specimens were tested after 24 hours, while the remaining specimens underwent 5,000 thermocycles. Shear bond strength (SBS) was measured using a universal testing machine, and failure modes were evaluated. Data were analyzed using three-way ANOVA and Bonferroni post hoc tests (α = .05). RESULTS: Thermocycling significantly reduced SBS values in all groups (P .001). In contrast, neither adhesive type (P = .065) nor application mode (P = .11) had a significant effect on bond strength. No significant interactions were found among the variables (P > .05). Failure mode analysis revealed predominantly adhesive and mixed failures, with an increase in adhesive failures after thermocycling. CONCLUSION: Polymerization mode and application strategy did not significantly influence dentin bond strength, whereas thermocycling reduced the durability of the adhesive interface. These findings suggest that aging-related factors may play a more critical role than differences in curing mechanism or application strategy. Clinically, the selection of polymerization mode alone may not be critical for bonding performance.