Surgical orthodontic correction of mandibular deficiency by sagittal osteotomy: clinical and cephalometric analysis of 1-year data.

A homogeneous sample of 76 mandibular retrognathic patients (mean age, 28 years) were examined for postoperative alterations after surgical treatment by bilateral sagittal split osteotomy and mandibular advancement with wire fixation. Skeletal and dental measures were obtained from preoperative, immediate postoperative, fixation-release, and 1-year cephalograms. Spearman correlation was used as a preliminary analysis to assess the relationship between postsurgical change and age, genioplasty, amount of mandibular advancement, and preoperative mandibular plane angle. Genioplasty and amount of mandibular advancement were included as independent factors in the subsequent repeated-measures analysis of variance, since these were the only two factors that showed a consistent trend of correlations with postoperative change. Genioplasty was a significant factor in the X and Y coordinate changes in pogonion, while the amount of mandibular advancement was a significant factor in the X coordinate movements of all mandibular landmarks except gonion and condylion. The mean amount of horizontal advancement was 5.2 mm, and anterior face height increased 5.1 mm. During fixation, B point moved posteriorly (x = -1.6 mm, p less than 0.01) and inferiorly (y = 1.0 mm, p less than 0.01). After fixation release, these trends were reversed, resulting in a nonsignificant net horizontal change (x = -0.5 mm, p = 0.10) and a significant net superior movement (y = -1.3 mm, p = 0.01) by 1 year. Pogonion, menton, and mandibular incisor tip showed similar patterns.(ABSTRACT TRUNCATED AT 250 WORDS)