title: Causes, location, and timing of relapse following rigid fixation after mandibular advancement.
abstract: The purpose of this study was to evaluate two different groups of patients who underwent bilateral sagittal split osteotomy for mandibular advancement. One group demonstrated no relapse, whereas a second group had documented relapse. The following questions were asked: 1) What factors contribute to relapse? 2) At what site in the mandible is movement seen? and 3) During what period does movement occur? A retrospective lateral cephalometric serial analysis was performed on 50 patients at multiple time intervals. Criteria for a candidate include 1) mandibular advancement surgery with rigid fixation, with or without genioplasty, 2) no maxillary surgery, and 3) relapse of 25% or more of the advancement. Of the 50 patients analyzed, 13 (26%) showed relapse of 25% or more and served as the relapse group. Twelve patients showed no relapse and served as the comparison group. Multiple-regression analysis for the relapse group showed that magnitude of advancement, increasing gonial arc and changing mandibular plane significantly accounted for 84.9% of the variance observed in relapse (P less than .001). Repeated-measures ANOVA showed that the majority of relapse occurred in the first 6 weeks after surgery (68%, P less than .05). Results of a paired t test showed that a significant change occurred in all the linear and angular measures except SN-AR-GO (P less than .05).
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center, San Antonio 78284-7908.
authors.forename: C J
authors.initials: CJ
authors.lastname: Gassmann
authors.forename: J E
authors.initials: JE
authors.lastname: Van Sickels
authors.forename: W J
authors.initials: WJ
authors.lastname: Thrash
mesh_terms: D000704:Analysis of Variance; D002508:Cephalometry; D005147:Facial Bones / Q000473:pathology*; D006801:Humans; D007103:Immobilization; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D010027:Osteotomy; D012008:Recurrence; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors