title: [Comparison of mandibular and chin morphology in adults with skeletal Class III malocclusion in different vertical facial types].
abstract: OBJECTIVE
  The purpose of this study was to compare the difference of mandibular and chin morphology in adults with skeletal Class III malocclusion in different vertical skeletal types, and to find the relationship among them.
  
  
  METHODS
  The pretreatment lateral cephalographs of 60 adults (30 males, 30 females, with an average age of 21±3.020 years) with skeletal Class III malocclusion[ANB<0° average (-3.927±2.7637)°] were selected randomly. They were divided into three groups according to mandibular plane angle: high angle group(20 cases,FH/MP<32°, average angle group(20 cases, 22°<FH/MP≥32° and low angle group(20 cases, FH/MP≤22°. Then the vertical and horizontal craniofacial pattern, mandibular and chin dimensions (angular, linear and proportional measurements) were measured and analyzed statistically using SPSS 16.0 software package.
  
  
  RESULTS
  Compared with the low and average angle groups, high angle subjects exhibited increased mandibular angle, chin height and curvature, and decreased chin minimal depth, chin minimal depth /depth ratio, depth/height ratio, chin angle(P<0.05). Further comparision of every two groups showed that there was significant difference in mandibular angle, chin minimal depth, chin minimal depth /depth ratio, chin height between low and high angle group, and between average and high angle group(P<0.05); There was significant difference in chin curvature between low and high angle group(P<0.05). Positive correlation was found between mandibular plane angle and mandibular angle, chin height and curvature, while negative correlation between mandibular plane angle and chin minimal depth, chin minimal depth /height ratio, depth/height ratio, chin angle.
  
  
  CONCLUSIONS
  Mandibular and chin morphology are different in adults with skeletal Class III malocclusion in different vertical skeletal types, and there is relationship between mandibular plane angle and mandibular and chin morphology, which deserve to be taken into consideration in orthodontic treatment plan.
authors.affiliation: Department of Stomatology, the Affiliated Hospital of Medical College, Qingdao University, Qingdao 266003, Shandong Province, China. shuyanhunan@126.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Shu
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Cun-hui
authors.initials: CH
authors.lastname: Fang
mesh_terms: D000328:Adult; D002508:Cephalometry; D002680:Chin; D005145:Face; D005260:Female; D006801:Humans; D008297:Male; D008313:Malocclusion, Angle Class III; D008334:Mandible