Stability of Bimaxillary Proclination Cases Following Fixed Appliances Treatment: A Randomised Controlled Trial
Lecture Description
Objectives : To identify the most effective retention strategy for corrected bimaxillary proclination cases treated with extraction of four premolars and pre-adjusted fixed appliance.
Material and Methods : 27 patients who had four premolars extraction and fixed appliance treatment at Faculty of Dentistry, Universiti Malaya were recruited and allocated by block randomisation into three groups [i.e., fixed bonded retainers (FB), double retainers (DR) and vacuum formed retainers (VFR)]. Data were collected periodically from debond (T0) up to 12 months (T4). The dental tissue (DT) and soft tissue (ST) parameters were measured from manually traced lateral cephalograms (LC). Dental casts were measured for intra-arch changes. Patients' compliance and frequency of breakages were also recorded. Data were analysed by repeated measures ANOVA.
Results : At 12 months, the ST cephalometric parameters show significant (p < 0.05) relapse for lower and upper lips to SN-7 line and labiomental fold angle. The DT cephalometric and study cast parameters revealed significant relapse for the upper incisor to SN-7 line, upper and lower incisor angulations and interincisal angle. Only the upper incisor angle (UIA) showed significant differences between groups (¥ç2 = 0.296; p = 0.015). Post-hoc comparisons found FB and VFR [(mean difference = 3.33 degrees; 95% CI 0.46, 6.21; p =0.019) and (mean difference =3.22 degrees; 95% CI -6.09, -0.35; p = 0.024), respectively] had more relapse than DR of the UIA at T4.
Conclusion : All three types of retainers showed no differences in most of the soft and dental tissue parameters. However, DR was found to be more superior than FB and VFR in maintaining the UIA of corrected bimaxillary proclinations.
October 28-30, 2022 ¡¤ COEX, Seoul, Korea