Objective: This study was conducted to evaluate the skeletal stability after mandibular osteotomy, the effect of the two-fixation method used (unilateral plate versus bilateral plates), the influence of condylar bony change, and the relationship between the magnitude of setback and the relapse.
Methods: Twenty-three patients who have mandibular prognathism with asymmetry were selected from a pool of orthodontic patients at the Department of Orthodontics, Niigata University Dental Hospital. To evaluate the stability after surgery, the lateral and frontal cephalograms taken just before surgery (T1), just after surgery (T2), and retention time (long term postoperatively, >6 months) (T3) were used.
Results: In general, the long-term post-operative stability term was satisfied. TMJ symptom was relieved after surgery. The The long-term relapse tendency was larger in those patients who had pre-operative condylar bony change. From our data, there was no significant difference about the long-term change due to post-operative skeletal relapse between bilateral SSRO cases and USSRO+IVRO cases. There was no correlation between the magnitude of setback and the long-term post-operative relapse.
Conclusion: It was suggested that even if condylar bony change existed before surgery, the patient could receive mandibular osteotomy and enjoy a good post-operative stability. Condylar bony change might be one of the risk factors for the stability after mandibular osteotomy in prognathic patients with mandibular asymmetry. The type of mandibular osteotomy, the fixation of mandibular and the amount of setback might have no relationship with the postoperative relapse in prognathism with mandibular deviation.