Simultaneous lengthening of both the mandible and maxilla by gradual distraction: Application to Murray's type II hemifacial microsomia

We treat hemifacial microsomia by early improvement of facial asymmetry and induction of normal growth employing surgery and orthodontic treatment before adolescent. For patients with type II of Murray's classification, we used to apply gradual distraction of the mandibular ramus. However, this technique mostly did not improve the occlusal plane, and resulting cross bite caused difficulties in postoperative orthodontic treatment. The mandibular angle region of the operated side looked flat, and the angle of the mouth remained elevated. We felt that for type II cases the maxilla should also be treated actively, so we devised a technique of simultaneous distraction of maxilla and mandible while occlusion is maintained using intermaxillary fixation. By the new technique, the position of the mandible was stabilized during distraction, and an optimal direction of elongation was attained as planned pre-operatively. The results have been morphologically and functionally satisfactory. After removal of the intermaxillary fixation at completion of distraction, relapse has been limited because of the Stable occlusion. As the patients are still growing, careful follow up and induction to normal growth are important, considering the possible growth disturbance of the affected side.