title: Longitudinal evaluation of dental arch asymmetry in Class II subdivision malocclusion with 3-dimensional digital models.
abstract: BACKGROUND
  Class II subdivision malocclusions with their asymmetric occlusal relationships often pose treatment difficulties. The aim of this study was to evaluate the longitudinal changes of dental arch asymmetry in untreated subjects with Class II subdivision malocclusion.
  
  
  METHODS
  From 706 files from the University of Michigan Growth Study, longitudinal records of 17 untreated subjects with Class II subdivision malocclusion were included this study. Dental arch changes at 3 consecutive longitudinal intervals, defined by the cervical vertebral maturation method, were analyzed on digital dental models. The average ages of the subjects were 12.4, 15.1, and 19.1 years at the 3 time periods, respectively. Maxillary and mandibular reference lines were constructed and used for the intra-arch asymmetry measurements. The Friedman test and analysis of variance with repeated measures were used to determine dental arch asymmetries at the P <0.05 level.
  
  
  RESULTS
  All subjects were found to have a type 1 Class II subdivision malocclusion characterized by distal positioning of the mandibular first molar on the Class II side. No statistically significant intra-arch asymmetry changes were found for the maxillary and mandibular dental arches in any time period. Between the baseline and the final follow-up, the data indicated decreases in maxillary and mandibular intercanine arch widths and arch lengths symmetrically.
  
  
  CONCLUSIONS
  The results of this study indicate that the dental arch asymmetry in patients with Class II subdivision malocclusions did not improve or worsen with growth.
authors.affiliation: Assistant professor, Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey.
authors.forename: Ilknur
authors.initials: I
authors.lastname: Veli
authors.affiliation: Research assistant, Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey.
authors.forename: Burcin
authors.initials: B
authors.lastname: Yuksel
authors.affiliation: Professor and head, Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey. Electronic address: tancanuysal@yahoo.com.
authors.forename: Tancan
authors.initials: T
authors.lastname: Uysal
mesh_terms: D000293:Adolescent; D000365:Age Determination by Skeleton; D059925:Anatomic Landmarks / Q000473:pathology; D002508:Cephalometry / Q000379:methods; D002574:Cervical Vertebrae / Q000254:growth & development; D002648:Child; D003481:Cuspid / Q000473:pathology; D003724:Dental Arch / Q000254:growth & development / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000473:pathology* / Q000503:physiopathology; D008334:Mandible / Q000254:growth & development / Q000473:pathology; D008437:Maxilla / Q000254:growth & development / Q000473:pathology; D003765:Models, Dental; D008963:Molar / Q000473:pathology; D012189:Retrospective Studies; D055815:Young Adult