A LATERAL CEPHALOMETRIC STUDY ON THE SOFT TISSUE CHANGES AFTER ORTHOGNATHIC SURGERY IN PATIENTSDIAGNOSED AS MANDIBULAR PROGNATHISM IN AJOU UNIVERSITY HOSPITAL

Abstract

It is essentianl for patients with mandibular prognathism to be treated by surgical means in correction of class Ⅲ patterns. In addition to fuctional aspect of the stomatognathic system, esthetic improvement of lower facial profile counts for something. Purpose of this study is the establishment of standard in soft tissue changes after orthognathic surgery in patients with mandibular prognathism. Two patient groups were selected, one was consisted of patients with mandibular prognathism who had undergone bilateral sagittal split ramus osteotomy (BSSRO) and the other was composed of patients with the same diagnosis who had undergone BSSRO plus posterior repoitioning genioplasty. The lateral cephalographs were taken preoperatively and at postoperative 6 month, traced with 0.5mm-thick pencil, and measured, respectively. The tracing and measurement were done by the author and by another collegeue with time difference to minimize systematic errors. The ratio of horizontal movement between soft and hard tissues has significnt correlations in lower facial profiles. The ratios are as follows; In BSSRO group, the rations were 1.00 for Si/B, 0.95 for Li/Id, and 1.02 for Pg'/Pg, respectively. In BSSRO plus posterior repositionning genioplasty group, the ratios were 1.06 for Si/B, 0.98 for Li/Id. But soft tissue pogonion (Pg') and pogonion(Pg) has moderate correlation(correlation coefficient was 0.766) with the ratio (Pg'/Pg) 0.774 in BSSRO plus posterior repositioning genioplasty group. We have endeavored after standards for orthognathic surgery for mandibular prognathism in BSSRO and BSSRO plus posterior repositioning genioplasty. The soft tissue profiles were generally predictable after BSSRO and BSSRO plus posterior repositioning genioplasty, but careful prediction is needed in prediction of soft tissue pognoion in BSSRO plus posterior repositioning genioplasty case.