Factors contributing to relapse in rigidly fixed mandibular setbacks.
The incidence of, and factors accounting for, relapse in 25 subjects who underwent mandibular setbacks via a bilateral sagittal split osteotomy with rigid fixation were studied. Fourteen had single-jaw operations, and the remaining 11 had concomitant maxillary procedures. Cephalometric radiographs were reviewed preoperatively, immediately postoperatively, and 6 months to 3 years after surgery. Relapse was defined as forward movement of pogonion during the postoperative period. No difference in the movement of the mandible in one- or two-jaw cases was noted. Even with excellent occlusal results, there was a tendency for the mandible (chin point) to rotate forward. In the one-jaw cases 43.7% relapse was noted, whereas 53.4% was seen in the two-jaw cases. A regression analysis showed that the magnitude of setback was the single factor that significantly predicted relapse in one-jaw cases, whereas alteration of the proximal segment accounted for relapse in two-jaw procedures. These results seem interrelated when considering alterations in the spatial arrangement of the muscular tissues and their attachments.
Franco
J E
JE
Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center, San Antonio 78284-7908.
Van Sickels
J E
JE
Thrash
W J
WJ
D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D002508:Cephalometry; D005260:Female; D006801:Humans; D007103:Immobilization; D008297:Male; D008334:Mandible / Q000033:anatomy & histology / Q000601:surgery*; D008437:Maxilla / Q000033:anatomy & histology / Q000601:surgery*; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011183:Postoperative Complications