title: Skeletal relapse after mandibular advancement and setback in single-jaw surgery.
abstract: OBJECTIVE
  The aim of this study was to identify contributing factors to skeletal relapse by analyzing cephalometric changes after bilateral sagittal split ramus osteotomy.
  
  
  METHODS
  This study included 60 consecutive patients who underwent either mandibular advancement (30 patients) or setback surgery (30 patients). There were 36 women and 24 men (mean age, 23 years). The radiographs of these patients taken immediately before operation, at 1 week, and 14 months postoperatively were studied. To analyze the influence of hyper- and hypodivergent facial patterns on the surgical outcome, the patients were divided into 3 groups according to the mandibulo-nasal plane angle. The position of the maxilla was also taken into account.
  
  
  RESULTS
  Measured at B-point, skeletal relapse was 1.3 mm (30%) after mean advancement of 4.4 mm and 0.8 mm (12%) after setback of 6.0 mm. The magnitude of the surgical movement correlated with skeletal relapse. However, the correlation was not linear. Advancement of greater than 7 mm is associated with an increased tendency to relapse (r=0.52), but setback of more than 12 mm with a decreased tendency (r=-0.95). The retrognathic patients with a high mandibulo-nasal plane angle (hyperdivergence) had 30% higher relapse rate. Patients with hypodivergent facial patterns had less relapse in both advancement and setback surgery.
  
  
  CONCLUSIONS
  Skeletal relapse was affected by magnitude of surgical movement and different facial patterns according to the mandibulo-nasal plane angle; however, influences of both factors were different between mandibular advancement and setback.
authors.affiliation: Department of Cranio-Maxillofacial Surgery, University of Berne, Switzerland. eggensperger@insel.ch
authors.forename: Nicole
authors.initials: N
authors.lastname: Eggensperger
authors.forename: Wenko
authors.initials: W
authors.lastname: Smolka
authors.forename: Akram
authors.initials: A
authors.lastname: Rahal
authors.forename: Tateyuki
authors.initials: T
authors.lastname: Iizuka
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D005147:Facial Bones / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000601:surgery; D008313:Malocclusion, Angle Class III / Q000000981:diagnostic imaging / Q000601:surgery*; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D019186:Mandibular Advancement / Q000009:adverse effects* / Q000379:methods; D008437:Maxilla / Q000000981:diagnostic imaging; D010027:Osteotomy / Q000379:methods; D011378:Prognathism / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012008:Recurrence; D063173:Retrognathia / Q000000981:diagnostic imaging / Q000601:surgery*; D017211:Treatment Failure; D014716:Vertical Dimension