Intraoral Vertical Ramus Osteotomy Results in Good Long-Term Mandibular Stability in Patients with Mandibular Prognathism and Anterior Open Bite

Purpose Few studies have evaluated the outcomes of intraoral vertical ramus osteotomy (IVRO) for the correction of skeletal Class III malocclusion with an anterior open bite and the potential for postoperative relapse. Therefore, this study evaluated the stability of outcomes of IVRO for mandibular prognathism with and without an anterior open bite. Material and Methods This retrospective cohort study included consecutive patients with skeletal Class III malocclusion with (AOB group) and without (NAOB group) an anterior open bite who underwent IVRO at Yonsei Dental Hospital (Seoul, Korea). Lateral cephalograms were analyzed for predictor (open bite, yes or no) and outcome (horizontal and vertical relapse in the mandible) variables before and 7 days, 1 year, and 2 years after surgery. Other variables included the patients' demographic characteristics. Data were analyzed using independent t tests, repeated measures analysis of variance, Pearson correlation coefficients, and multiple linear regression analysis. Results The 2 groups (n = 15 each) were matched for baseline demographic characteristics. During the 2-year postoperative period, anterior and superior mandibular movements were observed in the NAOB group, whereas posterior and superior movements were observed in the AOB group. However, there were no meaningful intergroup differences in horizontal and vertical relapses of the mandible at all time points, although the amount of postoperative inferior relapse increased with a decrease in the amount of initial overbite. Conclusions IVRO for the correction of skeletal Class III malocclusion resulted in good postoperative stability over time, regardless of the presence of a preoperative open bite, although the amount of postoperative inferior relapse showed a weak negative correlation with the initial overbite. Thus, IVRO can be a clinically acceptable treatment for skeletal Class III malocclusion with an anterior open bite.