title: Correlation between the change of gonial region and skeletal relapse after intraoral vertical ramus osteotomy for correction of mandibular prognathism.
abstract: BACKGROUND
  The gonial region is coincided with harmonious face and masticatory function. The aims of the present study were to assess changes in the gonial region in patients who had mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and to investigate the contributing factors in relation to skeletal relapse.
  
  
  METHODS
  Twenty-one patients with mandibular prognathism were corrected by IVRO. Three cephalometric radiographs were collected from preoperative orthodontic treatment (T1), immediately after surgery (T2), and at 2-year postoperative follow-up (T3). Relapse was defined as forward movement of menton (Me) after the 2-year follow-up. Three angular (SN-Go angle, mandibular plane angle, and gonial angle) and 2 linear (horizontal-Me and vertical-Me) measurements were compared after immediate operation and at the 2-year follow-up. Spearman rank correlation and Student t tests were used for statistical analysis.
  
  
  RESULTS
  The mean setback of the Me was 12.7 mm, and the mean relapse was 1.5 mm. The magnitude of setback was not significant for relapse. There were weak correlations between relapse and factors concerned with the gonial region (SN-Go angle, mandibular plane angle, and gonial angle).
  
  
  CONCLUSIONS
  Surgical correction of mandibular prognathism using IVRO can lead to an increase in the angle changes of gonial region but not correlate to skeletal relapse in long-term follow-up.
authors.affiliation: Departments of Family Dentistry, College of Dental Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Kun-Tsung
authors.initials: KT
authors.lastname: Lee
authors.forename: Steven Sheng-Tsung
authors.initials: SS
authors.lastname: Lai
authors.forename: Ju-Hui
authors.initials: JH
authors.lastname: Wu
authors.forename: Huey-Er
authors.initials: HE
authors.lastname: Lee
authors.forename: Chun-Ming
authors.initials: CM
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D005260:Female; D006801:Humans; D007574:Jaw Relation Record; D008297:Male; D010027:Osteotomy / Q000379:methods*; D011378:Prognathism / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012008:Recurrence; D016896:Treatment Outcome; D014716:Vertical Dimension