Bond failure rates of two self-ligating brackets: a randomised clinical trial

Aims: To evaluate the bond failure rates of two self-ligating appliance systems bonded with a self-etching primer.Methods: Forty patients were randomly assigned to either Group SC (SmartClip, 3M Unitek, Monrovia, CA, USA) or Group IR (In-Ovation R, GAC International, Bohemia, NY, USA) appliance groups. Seven hundred and sixty six brackets were bonded with Transbond Plus Self-Etching Primer and Transbond Plus Color Change Adhesive according to the manufacturer's instructions. Over a 12- month period, the survival rates of the brackets were estimated with the Kaplan-Meier analysis. The survival distributions for the appliance systems, dental arch and position in the dental arch were compared with the log-rank test.Results: The bond failure rate for SC was significantly lower than IR (p = 0.022). There were no differences in failure rates between either the maxillary and mandibular arches or between the anterior and posterior brackets.Conclusion: SC provided a more reliable bond than IR over the 12-month observation period, however, both brackets had clinically acceptable bond failure rates.