The effects of surgical-orthodontic correction of skeletal class III malocclusion on mandibular movement.

The effects of surgical-orthodontic treatment on mandibular movement were studied using the mandibular kinesiograph in 30 patients with skeletal class III malocclusion that was corrected by the sagittal split osteotomy (27 patients), a combination of the sagittal split osteotomy and body ostectomy (2 patients), or the sagittal split osteotomy and a posterior alveolar osteotomy of the maxilla (1 patient). Postoperatively, the mean maximum anterior and posterior excursions of the mandible increased significantly from 4.1 to 6.7 mm and from 0.6 to 2.6 mm, respectively. The lateral excursion to the right and left sides also showed significant increases from 4.8 to 7 mm and from 5.5 to 7 mm, respectively, after surgery. In analysis of the habitual and rapid opening and closing movements of the mandible, marked impairment was not observed in most patients except for crossing and discrepancy in the tracings of the habitual opening and closing movements in the sagittal plane observed in 11 patients. These findings were observed in only one patient postoperatively. The results indicate that the surgical orthodontic correction of skeletal class III malocclusion has favorable effects on the function of the mandible.