title: Chincup treatment modifies the mandibular shape in children with prognathism.
abstract: BACKGROUND
  Although chincups are the preferred treatment for growing children with mandibular prognathism, the mechanism by which chincups improve this condition remains unclear. The aim of this study was to use geometric morphometrics to evaluate changes in the shape of the mandible of prognathic children treated with a chincup.
  
  
  METHODS
  Geometric morphometrics were used to evaluate the short-term mandibular shape changes in 50 prognathic children treated with chincups compared with 40 untreated matched controls. Twenty-one 2-dimensional mandibular landmarks from cephalograms taken before and after 36 months of treatment or observation were analyzed by Procrustes superimposition and thin plate spline.
  
  
  RESULTS
  Permutation tests of the treated patients showed highly significant differences in the mandibular shapes before and after treatment, and compared with the control group after the observation period. The thin plate spline grid deformations indicated more rectangular mandibular configuration, forward condyle orientation, condyle neck compression, gonial area compression, and symphysis narrowing.
  
  
  CONCLUSIONS
  Early chincup treatment widely modifies the mandibular shape of prognathic children to improve Class III malocclusion.
authors: Department of Stomatology, Area of Orthodontics, School of Dentistry, University of Granada, Granada, Spain. jalarcon@ugr.es
authors: José Antonio
authors: JA
authors: Alarcón
authors: Markus
authors: M
authors: Bastir
authors: Antonio
authors: A
authors: Rosas
authors: Julia
authors: J
authors: Molero
mesh_terms: D016022:Case-Control Studies; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D002680:Chin / Q000033:anatomy & histology / Q000473:pathology; D005115:Extraoral Traction Appliances; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008137:Longitudinal Studies; D008297:Male; D008313:Malocclusion, Angle Class III / Q000628:therapy*; D008334:Mandible / Q000033:anatomy & histology* / Q000473:pathology; D015999:Multivariate Analysis; D011378:Prognathism / Q000628:therapy*; D012189:Retrospective Studies; D013382:Subtraction Technique