are bonding agents being effective on the shear bond strength of orthodontic brackets bonded to the composite?

Introduction: one of the clinical problems in orthodontics is the bonding of brackets to composite restorations. the aim of this study was to evaluate the shear bond strength of brackets bonded to composite restorations using excite. methods: forty brackets were bonded to composite surfaces, which were embedded in acrylic resin. one of the following four protocols was employed for surface preparation of the composite: group 1) 37% phosphoric acid for 60 seconds, group 2) roughening with a diamond bur plus 37% phosphoric acid for 60 seconds, group 3) 37% phosphoric acid for 60 seconds and the applying excite®, group 4) roughening with diamond bur plus 37% phosphoric acid for 60 seconds and applying excite®. maxillary central brackets were bonded onto the composite prepared samples with transbond xt. shear bond strength (sbs) was measured by a universal testing machine. the anova and tukey test was utilized for data analysis. results: there was a significant difference between the four groups (p<.000). the lowest and highest sbs were attributed to thegroup 1 and group 4 respectively. there was no significant difference between groups 1 & 3, 2 & 3 and 2 & 4. however, differences between group 1in comparison with groups 2 and 4 and group 3 with group 4 were statistically significant. conclusion: according to the results of this study, the usage of excite® alone beforebonding brackets to composite restorations does not cause an increase in bond strength. however, roughening the composite surface before applying excite is very effective for improving the bond strength of orthodontic brackets to composite restorations