Evaluation of the effect of restoration time and different surface treatments on the bond strength of orthodontic brackets adhesived on restoration

This in vitro study aimed to evaluate the effects of different surface treatments applied to restorative materials on bracket bond strength. Additionally, the influence of the timing of bracket bonding—whether performed immediately after restoration or after a delayed period—was investigated. A total of 168 samples were divided into early (bracket bonded in the same session as restoration) and late (bracket bonded after 15 days of aging in 37°C distilled water) groups. Each group was further subdivided into six subgroups based on surface treatment methods, including no treatment, diamond bur, 37% phosphoric acid, air abrasion, and 9.6% hydrofluoric acid. After surface treatments, metal brackets were bonded, and shear bond strength tests were performed. Post-debonding, surfaces were examined under a stereomicroscope and scored using the Adhesive Remnant Index (ARI). Data were analyzed using one-way ANOVA, Tukey's HSD, and Chi-square tests. The highest mean bond strength was found in the untreated early group, while the lowest was in the untreated late group. The difference between these two groups was statistically significant (p<0.001). In early groups, untreated surfaces showed the highest bond strength, whereas the diamond bur group had the lowest. In late groups, the highest bond strength was observed in the diamond bur + phosphoric acid group, and the lowest in the untreated group (p<0.001). All groups demonstrated clinically acceptable bond strengths. Bonding brackets in the same session as restoration placement offers a clinical advantage in terms of resin-resin adhesion. When immediate bonding is not possible, effective surface treatments such as diamond bur, phosphoric acid, or air abrasion can improve bond strength outcomes.