title: Method to classify dental arch forms.
abstract: BACKGROUND
  The aim of this study was to propose a method to classify dental arch forms of subjects with normal occlusion into several types that can ensure both goodness of fit and clinical application.
  
  
  METHODS
  We selected 306 subjects with normal occlusion from 15,836 young adults, recorded 14 reference points that defined the distance between 2 arch forms as the area between 2 arches, and then classified the dental arch forms by using the partitioning around medoids clustering and silhouette method. We measured tooth size, arch width, basal arch width, arch depth, mesiodistal angulations, and buccolingual inclinations.
  
  
  RESULTS
  We identified 3 types of arch forms, and cross-classification of the maxillary by mandibular arch forms showed a more frequent distribution in the diagonal elements than in the off-diagonal elements. The 3 arch forms showed differences in tooth size, arch width, basal arch width, and inclination of the posterior teeth.
  
  
  CONCLUSIONS
  By defining area discrepancies as distance measures and applying them to the cluster method by using medoids, the dental arch form can be classified keeping control for the extremes without bias. It is hoped that this method will have possible clinical applications in determining the shape and number of preformed orthodontic arch forms.
authors: Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
authors: Shin-Jae
authors: SJ
authors: Lee
authors: Sungim
authors: S
authors: Lee
authors: Johan
authors: J
authors: Lim
authors: Heon-Jin
authors: HJ
authors: Park
authors: Timothy T
authors: TT
authors: Wheeler
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002508:Cephalometry / Q000706:statistics & numerical data; D002965:Classification / Q000379:methods*; D016000:Cluster Analysis; D003724:Dental Arch / Q000033:anatomy & histology*; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D009811:Odontometry; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D012016:Reference Values; D018709:Statistics, Nonparametric; D055815:Young Adult