The effect of different reconditioning methods on bond strength of rebonded brackets: An in-vitro study

Abstract

AIM: To evaluate the effect of three different reconditioning techniques on the shear bond strength (SBS) of rebonded brackets. MATERIALS AND METHODS: Forty-five orthodontic brackets were bonded to human premolar teeth using TransbondTMXT. After debonding, the samples were randomly assigned into equal groups to assess three techniques for the removal of residual adhesive from bracket bases: in Group A, each bracket base was sandblasted with aluminum oxide; in Group B1, each base was cleaned superficially with a greenstone bur; and in Group B2, the bases were thoroughly abraded with a greenstone bur. Subsequently, brackets were rebonded and the SBS and the adhesive remnant index (ARI) were determined. Data were analyzed using one-way analysis of variance (ANOVA), plus Tukey and Kruskal–Wallis post-hoc tests (P ≤ 0.05). RESULTS: The average SBSs were: Group A, 11.75 (±4.83) MPa; Group B1, 8.22 (±4.01) MPa; and Group B2, 7.54 (±2.85) MPa. No statistically significant differences in SBS were found between Groups A and B1 (P = 0.051) and Groups B1 and B2 (P = 0.885), but there was a significant difference between Groups A and B2 (P = 0.016). Regarding ARI scores, there were statistically significant differences between Groups A and B2 (P < 0.001) and between B1 and B2 (P = 0.014), but not between Groups A and B1 (P = 0.068). CONCLUSION: All reconditioning methods were found to have a positive effect, but the sandblasting technique performed best. Brackets reconditioned by sandblasting and superficial grinding mainly showed mixed-type failure, while in samples thoroughly reconditioned by greenstone bur, bonding failure occurred predominantly at the adhesive/bracket interface.

Keywords

• adhesive remnant index
• in-vitro
• recycled brackets
• shear bond strength