title: Stability of Pre-Orthodontic Orthognathic Surgery Using Intraoral Vertical Ramus Osteotomy Versus Conventional Treatment.
abstract: OBJECTIVE
  Postoperative skeletal and dental changes were evaluated in patients with mandibular prognathism who underwent mandibular setback surgery using an intraoral vertical ramus osteotomy (IVRO) with and without presurgical orthodontic treatment.
  
  
  METHODS
  This retrospective cohort study included consecutive patients with skeletal Class III malocclusions who underwent IVRO. Patients treated with pre-orthodontic orthognathic surgery (POGS) were compared with patients treated with conventional surgery (CS) with presurgical orthodontics (control) using lateral cephalograms (taken preoperatively, 7 days postoperatively, and 12 months postoperatively). Predictor (group and timing), outcome (cephalometric measurements over time), and other (ie, baseline characteristics) variables were evaluated to determine the differences in postoperative horizontal and vertical positional changes of the mandible, such as point B. Baseline demographics were similar between the groups (N = 37; CS group, n = 17; POGS group, n = 20). The data were analyzed with an independent t test, the Mann-Whitney U test, the Fisher exact t test, Pearson correlation analysis, and simple linear regression analysis.
  
  
  RESULTS
  The mean setback of the mandible at point B was similar, but the mandible of the POGS group, particularly the distal segment, moved superiorly during the postoperative period in conjunction with the removal of premature occlusal contacts (P < .001). In the CS group, the mandible had significantly more backward movement 12 months after surgery compared with the POGS group (P < .01). In the POGS group, horizontal and vertical postsurgical changes were linearly correlated with the amount of setback and vertical movement of the mandible.
  
  
  CONCLUSIONS
  Mandibular setback surgery using IVRO without presurgical orthodontics leads to considerably different postoperative skeletal and dental changes compared with conventional treatment, with more superior movement being observed at point B during the 1-year postoperative period.
authors.affiliation: Fellow, Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Professor, Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Chung-Ju
authors.initials: CJ
authors.lastname: Hwang
authors.affiliation: Professor, Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Hyoung-Seon
authors.initials: HS
authors.lastname: Baik
authors.affiliation: Professor, Department of Oral and Maxillofacial Surgery, Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Jung
authors.affiliation: Professor, Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea. Electronic address: orthojn@yuhs.ac.
authors.forename: Kee-Joon
authors.initials: KJ
authors.lastname: Lee
mesh_terms: D020341:Absorbable Implants; D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D002508:Cephalometry / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019248:Jaw Fixation Techniques; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery; D008334:Mandible / Q000473:pathology; D063168:Mandibular Osteotomy / Q000295:instrumentation / Q000379:methods*; D008437:Maxilla / Q000473:pathology; D056948:Orthognathic Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D019340:Osteotomy, Le Fort / Q000295:instrumentation / Q000379:methods; D011378:Prognathism / Q000601:surgery; D012189:Retrospective Studies; D014087:Tooth Movement Techniques / Q000379:methods; D016896:Treatment Outcome; D014716:Vertical Dimension; D055815:Young Adult