Objective: To compare the clinical performance of self-ligating and edgewise brackets with different base designs during an 18-month period.
Materials and Methods: In thirty-nine patients, 688 American Orthodontics (AO) Time2 self-ligating brackets with an integral quadra grip base were bonded with a split-mouth design, using Transbond Plus Self-Etching Primer (SEP) or a conventional two-step etch and Transbond XT primer (CM). In thirty-eight patients, 686 AO Mini Master Series edgewise brackets with a mesh base were bonded in the same way as aforementioned. The survival rate of the brackets was estimated by the Kaplan-Meier analysis. Bracket survival distributions with respect to bracket type, bonding procedure, dental arch, type of tooth (incisor, canine and premolar) and patients’ gender were compared using the log-rank test. Bond failure location was determined with the Adhesive Remnant Index (ARI).
Results: Bond failure rates of SEP and CM were 3.3% and 1.7%, respectively. A significant difference was not found between the bonding procedures using the log-rank test (P = 0.059). The bond failure rates of Time2 and Mini Master Series brackets were 3.8% and 1.3%, respectively. A significant difference was found between the brackets (P = 0.004). Furthermore, canine and premolar teeth displayed a lower survival rate than the incisor teeth (P = 0.001). No significant difference was observed for the ARI scores of bracket type and bonding procedure (P > 0.05).
Conclusion: Survival rate was affected by the bracket type and base design; however, it was not affected by the bonding procedure.