Factors associated with the stability of compensatory orthodontic treatment of Class III malocclusion in the permanent dentition

Abstract

This study aimed to assess the stability of compensatory treatment of Class III malocclusion in permanent dentition. Thirty-six patients (21 women and 15 men; mean age, 20years) with Class III malocclusion were subjected to the compensatory treatment of permanent dentition and followed up for at least 3years after orthodontic treatment (T3). Multivariate Poisson regression was performed to assess the influence of clinical, cephalometric, and dental cast variables at the beginning (T1) and the end of treatment on the stability of Class III malocclusion. Overjet changed from -0.25mm (-3 to 0.5mm) at T1 to 1.4mm (1-2.5mm) at the end of treatment and 0.8mm (0-1.5mm) at T3. Clinical relapse (overjet<1mm and/or canine Class III relations) was observed in 11 patients (30.6%). Patients treated with extraction of mandibular premolars (risk ratio [RR]=2.13×10-07, P<0.001), with better orthodontic end outcomes (RR=1.16, P=0.009) and which had lower maxillary incisor inclination at T1 (RR=1.08, P=0.035) showed a lower risk of relapse. Demographic (sex, age), clinical (length of treatment and posttreatment, number of treatment phases, time of Class III elastics), cephalometric (SNA, SNB, ANB, Wits appraisal, SNGoGn, IMPA), and dental cast (peer assessment rating index and arch dimensions) variables were not significantly associated with clinical relapse at T3. The stability of compensatory treatment of Class III malocclusion in permanent dentition is multifactorial, with few predictive variables. Patients treated with extraction and better orthodontic finishing had a lower risk of relapse, whereas larger maxillary incisor inclination at baseline increased the risk of relapse.