Survival rates of mandibular fixed retainers: comparison of a tube-type retainer and conventional multistrand retainers

Objective The purposes of this study were to evaluate the survival rate of a tube-type mandibular fixed retainer and compare it to conventional multistrand retainers. Materials and methods In all, 66 patients who had completed their orthodontic treatment were enrolled in this study. They were allocated randomly to a tube-type retainer group or a 0.020 multistrand fixed retainer group. In case of the tube-type retainer, a thermoactive 0.012 NiTi was placed into 6 mini-tubes passively bonded to the anterior teeth. The patients were recalled at 1, 3, 6, 12, and 24 months after retainer placement. During the 2‑year follow-up period, any first-time failure of retainers was recorded. Kaplan–Meier survival analysis and log-rank tests were used to compare the failure rates between the two types of retainers. Results Of the 34 patients, 14 (41.2%) showed failure in the multistrand retainer group, whereas only 2 of 32 (6.3%) reported failure in the tube-type retainer group. There was a statistically significant difference in failure between the multistrand retainer and the tube-type retainer (log-rank test, P = 0.001). The hazard ratio was 11.937 (95% confidence interval 2.708–52.620; P = 0.005). Conclusion The tube-type retainer can be used with fewer concerns about recurrent retainer detachments during orthodontic retention.