Shear bond strength of self-ligating brackets

The aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of conventional and self-ligating brackets. Conventional stainless steel brackets (group 1, Step®; Leone) and three different passive and interactive self-ligating brackets (group 2, Smart Clip®, 3M Unitek; group 3, Quick®, Forestadent; and group 4, Damon 3MX®, Ormco) were tested. Four groups of 20 specimens each were bonded with an adhesive system (Ortho Solo® primer, Ormco and Transbond XT resin, 3M Unitek) onto bovine enamel and subsequently tested using an Instron universal testing machine. SBS values and adhesive failure rate were recorded. Statistical analysis was performed with analysis of variance and Scheffé tests to determine bond strength values, whereas a chi-square test was used for ARI scores. Groups 2 and 4 showed significantly higher SBS values than the other two groups. Moreover, groups 1 and 3 showed a higher frequency of ARI score 1, whereas groups 2 and 4 showed higher frequency of ARI score 2. All the brackets demonstrated a clinically adequate SBS.