Long-Term Study of Relapse After Mandibular Orthognathic Surgery: Advancement Versus Setback

Background Relapse is a continuing process and should be evaluated on a long rather than short term. Materials and Methods Treatment records of 46 patients who underwent mandibular orthognathic surgery were divided into two groups, i.e. Group 1: Mandibular Advancement (MA) surgery (n = 26) and Group 2: Mandibular Setback (MS) surgery (n = 20). Lateral cephalograms were traced at T0 (01 week before surgery), T1 (01 week after surgery), T2 (01 year after surgery) and T3 (minimum 05 years after surgery) to study short- and long-term skeletal and dental relapse in horizontal, vertical and angular parameters selected for the study. Relapse was correlated with gender, age, amount of surgical movement and intra-operative change in mandibular plane angle to study effect of these factors on relapse. Results All horizontal, vertical and angular parameters studied showed significant relapse at short term (from T1 to T2) which continued significantly till long-term evaluation (T2 to T3) in both groups (Pvalue < 0.001). Horizontal relapse in all parameters, vertical relapse in all parameters (except Pog and overbite at T1-T2) and angular relapse in all parameters (except Ramus inclination at T1-T2) was significantly higher in Group 2 compared to Group 1 (Pvalue < 0.001 for all). Relapse showed significant and positive correlation with amount of surgical movement and intra-operative change in mandibular plane angle in both groups (Pvalue < 0.05 for all). Conclusion Both MA and MS surgeries show significant relapse on both short- and long-term evaluation which it is higher in MS as compared to MA surgeries.