Effect of adhesive type and silane application on the repair bond strength of aged bulk-fill composites

Objective: This study evaluated the effects of different adhesive strategies and silane application on the repair bond strength of bulk-fill composites.Methods: Seventy specimens were prepared using a bulk-fill condensable composite. After thermocycling, they were randomly divided into five groups (n = 14) based on the bonding protocol: Group 1: Gluma Bond 5 (two-step etch-and-rinse), Group 2: Silane + Gluma Bond 5, Group 3: Gluma Bond Universal (self-etch mode), Group 4: Silane + Gluma Bond Universal (self-etch mode), and Group 5: Gluma Bond Universal (etch-and-rinse mode). The repair process involved treating the aged composite surface according to the assigned adhesive protocol, after which bulk-fill composite was placed in molds positioned against the treated surface to complete the restoration. Shear bond strength (SBS) was measured using a universal testing machine, and failure modes were determined. The data were analyzed using one-way ANOVA and Fisher’s exact test (α = 0.05).Results: The mean SBS values (MPa) were: Group 1 = 9.37 ± 3.04, Group 2 = 8.37 ± 2.86, Group 3 = 7.44 ± 3.43, Group 4 = 8.27 ± 3.34, and Group 5 = 7.27 ± 2.65. No statistically significant differences were found in bond strength (P = 0.393) or failure mode distribution (P = 0.422) among the groups.Conclusions: Neither the adhesive type (etch-and-rinse versus universal) nor the application mode of universal adhesive (self-etch versus etch-and-rinse) significantly affected the repair bond strength of aged bulk-fill composites. In addition, silane application did not improve bond strength during composite repair.