Bond strengths and adhesive remnant index of self-etching adhesives used to bond brackets to instrumented and uninstrumented enamel.

Purpose: This study evaluated bond strengths of orthodontic brackets to instrumented and uninstrumented enamel using self-etching adhesive systems when compared to a total-etch adhesive system. The adhesive remnant index (ARI) was also determined after debonding.

Methods: 140 bovine incisors were included in acrylic resin, and divided randomly in two groups: instrumented vs. uninstrumented enamel. For the instrumented enamel, specimens had their facial enamel ground flat to 600-grit. In each group, specimens were subdivided into four experimental subgroups according to the adhesive technique used: Transbond Plus, Adper Prompt L-Pop, iBond, and Adper Single Bond, applied following manufacturers' instructions. Orthodontic brackets were bonded to the treated instrumented or uninstrumented enamel with Transbond XT light-cured resin-based composite cement, and the bond strength was tested in shear mode after 7 days. One group where no etch and no adhesive were used served as a control. ARI scores were determined after debonding.

Results: There was no statistically significant difference in mean bond strengths between instrumented and uninstrumented enamel for any of the adhesive systems (P > or = 0.05). No significant differences were observed for bond strengths among the adhesives tested (P = 0.308), and all experimental groups resulted in mean bond strengths significantly higher than the controls (P < 0.05). Statistically significant differences were identified when ARI scores were compared, with less adhesive remnants being observed for iBond (uninstrumented enamel) and the control groups (P < 0.05).