The purpose of this study is to determine the preferred method of fixation to avoid relapse following maxillary and mandibular osteotomy to correct facial developmental deformities. Correlations are being established between semirigid and nonrigid fixation techniques, and the degree of relapse as measured by cephalometric techniques utilizing metallic markers implanted in the maxillae and mandible 6 months prior to orthognathic surgery. Changes in the height or the width of the attached gingiva are being recorded. Pre and post-operative changes in facial contours and occlusion are being measured. In addition, movements of the tongue, mandible and associated soft tissues during speech and swallowing are being assessed with ultrasound imaging procedures. Initial results observed at 3, 6 and 12 months did not demonstrate a significant difference in relapse between the two groups. However, patients treated with semirigid fixation experienced better diet, speech, and oral hygiene compared to patients with rigid internal fixation. Initial results of the swallowing tests demonstrate that maximal physical adjustment in the mandibular-hyoid relationship occurs in the first three months following the surgery. Functional changes continue to occur throughout the year. There appears to be a positive relationship between the surgical procedure and swallowing function. Both procedures serve to normalize the rate of swallowing, i.e. to decrease the duration of swallowing after surgery. Mandibular reduction patients were more abnormal in their pre-surgery duration (i.e. they took longer and required more effort to swallow before surgery).
