title: Stability after distraction osteogenesis to lengthen the mandible: results in 50 patients.
abstract: OBJECTIVE
  The purpose of this study was to investigate mandibular stability after lengthening the mandible by means of distraction.
  
  
  METHODS
  Fifty patients (mean age, 14.7 years; range, 11.2 to 37.3 years) with Angle Class II mandibular hypoplasia were treated by bilateral distraction osteogenesis to lengthen the mandible. Patients were divided into a high-angle group, with a high mandibular angle (sella/nasion-mandibular plane [SN-MP] >38 degrees), and a normal-to-low mandibular angle group (SN-MP <or=38 degrees). Clinical measurements and standardized cephalometric radiographs were taken just before operation; postdistraction at time of removal of the distraction devices, and 6 months and 1 year postoperatively. Analysis was performed by means of angle measurements: sella/nasion-maxilla point A (SNA), sella/nasion-mandibular point B (SNB), and SN-MP.
  
  
  RESULTS
  Eight of 14 high-angle patients showed a degree of relapse (57%), and only 3 of 36 patients showed relapse in the low/normal-angle group (8.3%).
  
  
  CONCLUSIONS
  It can be concluded that high-angle patients are still at risk of relapsing and that distraction osteogenesis cannot prevent relapse in cases with a high mandibular plane angle. For low-angle patients, however, distraction is a safe and predictable procedure.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Gelderse Vallei Hospital, Ede, The Netherlands. strijenp@zgv.nl
authors.forename: P J
authors.initials: PJ
authors.lastname: van Strijen
authors.forename: K H
authors.initials: KH
authors.lastname: Breuning
authors.forename: A G
authors.initials: AG
authors.lastname: Becking
authors.forename: D B
authors.initials: DB
authors.lastname: Tuinzing
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000601:surgery*; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D008437:Maxilla / Q000000981:diagnostic imaging; D009666:Nose / Q000000981:diagnostic imaging; D019857:Osteogenesis, Distraction; D010027:Osteotomy; D011859:Radiography; D012008:Recurrence; D012189:Retrospective Studies; D012658:Sella Turcica / Q000000981:diagnostic imaging; D016896:Treatment Outcome