Stability after sagittal split ramus osteotomy without post-operative maxillomandibular fixation in the treatment of prognathic patients with asymmetric mandibles.

Abstract

To examine post-operative stability in prognathic patients with mandibular asymmetry who underwent sagittal split ramus osteotomy (SSRO) of the mandible and titanium screw fixation without post-operative maxillomandibular fixation (MMF). Skeletal and dental changes after surgery with and without post-operative MMF were compared between prognathic patients with symmetric and asymmetric mandibles. Second Department of Oral and Maxillofacial Surgery at Tokyo Medical and Dental University. Twenty prognathic patients were examined. An appliance for repositioning the proximal segment was applied in all 20 patients. Ten patients with symmetric mandibles received post-operative MMF with stainless steel wires and intermaxillary rubber traction after the removal of MMF (Group I), while the other 10 patients with asymmetric mandibles underwent post-operative intermaxillary rubber traction only (Group II). Posteroanterior cephalograms were obtained pre-operatively; 2-3 days post-operatively; and 3, 6, and 12 months after surgery. Changes in the positions of the gonion points (Go) and upper and lower incisors (U-1 and L-1) were examined. In both groups, the Go tended to shift laterally as a consequence of the operation. Although the tendencies of the post-operative changes in the Go points of Groups II and I were different, statistical analyses revealed no significant differences between the two groups. At the last stage of the follow-up period, the absolute value of the change in L-1 tended to be larger in Group II than in Group I, but without any statistical significance. This study suggests that post-operative change in prognathic patients with asymmetric mandibles treated without post-operative MMF is comparable to that in patients with symmetric mandibles treated with post-operative MMF. Accordingly, post-operative MMF may be avoided, even in prognathic patients with asymmetric mandibles.