A randomized clinical trial of thermoplastic retainer wear.

The purpose of this study was to determine whether thermoplastic retainers need to be worn full-time for a limited period or whether part-time wear from the outset is adequate to maintain tooth position, arch form, and occlusion. This study was a randomized clinical trail, conducted in a district general hospital. Sixty-two participants were enrolled in the study. Group 1, full-time wear, consisted of 30 patients (12 males and 18 females, aged 13.6 +/- 1.5 years) and group 2, part-time wear, 32 patients (14 males and 18 females, aged 13.8 +/- 1.5 years). Each patient was assigned to one of the groups by random number generation. Clinical records in the form of study models were taken at the start of active treatment (T1), at debond (T2), 6 months into the retention phase (T3), and 1 year post-debond (T4). The irregularity index, intercanine width, intermolar width, arch length, overbite, overjet, and Peer Assessment Rating (PAR) scores were measured on study models using digital callipers. A Mann-Whitney test was used to evaluate the treatment changes within each group. The only statistically significant difference was found to be at T3 and T4 for overbite (P = 0.05 and P = 0.02, respectively). PAR scoring showed more variable changes in group 2. There was good correlation for the measurement method. There was no statistical difference for the two groups for overjet, arch length, intermolar width, intercanine width, and irregularity index at any time point.