title: Is There a Difference in Stability After Intraoral Vertical Ramus Osteotomy Between Vertically High-Angle and Normal-Angle Patients?
abstract: OBJECTIVE
  Few studies have evaluated the relapse pattern of intraoral vertical ramus osteotomy (IVRO) for the correction of mandibular prognathism with a high angle. The aim of this study was to measure the association between vertical facial types (high and normal mandibular plane angle) and relapse after IVRO for the management of mandibular prognathism.
  
  
  METHODS
  The retrospective cohort study sample (skeletal Class III patients) was divided into 2 groups according to the angle of the sella-nasion plane relative to the mandibular plane (SN-MP) at the initial examination. Lateral cephalograms were analyzed for the predictor (facial type) and outcome (cephalometric changes over time) variables before surgery, 7 days after surgery, and 12 months after surgery. The 2 groups were matched for sample size (n = 20 in each). Data were analyzed using repeated-measures analysis of variance with Bonferroni correction.
  
  
  RESULTS
  The normal-angle group (group N, SN-MP from 27° to 37°) and high-angle group (group H, SN-MP >37°) were not significantly different in terms of gender and age at the initial examination. Seven days after surgery, the mandibles in group H moved 2.5 mm more superiorly than those in group N (P = .013); consequently, the amount of overbite correction in group H was approximately 2 mm greater than that in group N (P = .002). Nevertheless, 12 months after surgery, there was no statistically significant difference in relapse of the maxilla and mandible between the 2 groups. In the 2 groups, the mandible moved approximately 0.7 mm superiorly during retention.
  
  
  CONCLUSIONS
  These findings suggest that IVRO is a clinically acceptable and stable treatment modality for mandibular prognathism with a high angle.
authors.affiliation: Fellow, Department of Orthodontics, The Institute of Cranial-Facial Deformity, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Graduate Student, Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Da-Young
authors.initials: DY
authors.lastname: Kang
authors.affiliation: Associate Professor, Department of Orthodontics, The Institute of Cranial-Facial Deformity, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Jung-Yul
authors.initials: JY
authors.lastname: Cha
authors.affiliation: Professor, Department of Oral & Maxillofacial Surgery, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Jung
authors.affiliation: Professor, Department of Orthodontics, The Institute of Cranial-Facial Deformity, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Hyoung-Seon
authors.initials: HS
authors.lastname: Baik
authors.affiliation: Professor, Department of Orthodontics, The Institute of Cranial-Facial Deformity, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Electronic address: hwang@yuhs.ac.
authors.forename: Chung-Ju
authors.initials: CJ
authors.lastname: Hwang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002508:Cephalometry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery*; D008334:Mandible / Q000033:anatomy & histology* / Q000601:surgery; D008875:Middle Aged; D059229:Osteotomy, Sagittal Split Ramus; D012008:Recurrence; D012189:Retrospective Studies; D016896:Treatment Outcome; D014716:Vertical Dimension; D055815:Young Adult