title: [The analysis of arch form before and after orthodontic treatment on patients with Angle II(1) malocclusion].
abstract: OBJECTIVE
  To compare and analyze the changes in the arch form after orthodontic treatment for patients with Angle II1 malocclusion by Beta function in the description of arch form.
  
  
  METHODS
  17 patients (6 males,11 females ) with Angle II1 malocclusion were selected, with an average age of 13.8 years.Before and after orthodontic treatment, study models were obtained. The occlusal surfaces of the models were scanned with a ruler in the field. The contact point of the central incisors, the cusp tips of the canines and the distobuccal cusp tips of the first molars were used to determine the curve. The results were analyzed for paired t test using SPSS11.0 software package.
  
  
  RESULTS
  The width of the dental arch changed significantly after treatment (P<0.05). The posterior length of the dental arch changed significantly (P<0.001). The maxillary and mandibular arch shapes didn't change before and after treatment.
  
  
  CONCLUSIONS
  The arch form includes arch size and arch shape. The arch size should be changed for the need of orthodontic treatment, but the arch shape can't be changed to obtain long-term stabilization of treatment results.
authors.affiliation: Department of Orthodontics, Shenyang Stomatological Hospital, Shenyang 110002, China. Lijiqiang_@126.com
authors.forename: Ji-qiang
authors.initials: JQ
authors.lastname: Li
authors.forename: Ji-kun
authors.initials: JK
authors.lastname: Zhu
mesh_terms: D002508:Cephalometry; D003724:Dental Arch / Q000033:anatomy & histology*; D003729:Dental Care; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion; D008437:Maxilla; D008963:Molar; D009967:Orthodontic Appliances; D014070:Tooth; D016896:Treatment Outcome