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 = ۱۴) based on the bonding protocol: Group ۱: Gluma Bond ۵ (two-step etch-and-rinse), Group ۲: Silane + Gluma Bond ۵, Group ۳: Gluma Bond Universal (self-etch mode), Group ۴: Silane + Gluma Bond Universal (self-etch mode), and Group ۵: 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 = ۰.۰۵).Results: The mean SBS values (MPa) were: Group ۱ = ۹.۳۷ ± ۳.۰۴, Group ۲ = ۸.۳۷ ± ۲.۸۶, Group ۳ = ۷.۴۴ ± ۳.۴۳, Group ۴ = ۸.۲۷ ± ۳.۳۴, and Group ۵ = ۷.۲۷ ± ۲.۶۵. No statistically significant differences were found in bond strength (P = ۰.۳۹۳) or failure mode distribution (P = ۰.۴۲۲) 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.

Keywords:

bonding agent , Bond Strength , Dental restoration repair , resin composite , Self-etch , silane