title: [Changes in arch width after extraction and nonextraction treatment].
abstract: OBJECTIVE
  To compare the changes of arch width in anterior and posterior arch after extraction and nonextraction treatment.
  
  
  METHODS
  The pre- and post-treatment study model of 50 patients were randomly selected and measured,of which 25 patients with 4 pre-molar extraction was in the extraction group, while 25 patient with nonextraction treatment was in the nonextraction group. SPSS 11.0 software package was used for Chi-square and pared t test.
  
  
  RESULTS
  The maxillary intercanine mean width was increased in both groups , but changes between the two groups were not statistically significant. The mandibular intercanine width of the extraction group was increased greater than the nonextraction group(P<0.01).In both groups, changes of inter second-molar width were not statistically significant.
  
  
  CONCLUSIONS
  Extraction treatment does not result in narrower dental arches than nonextraction treatment.
authors.affiliation: Department of Orthodontics, School of Stomatology, Shandong University, Jinan 250012, Shandong Province, China. dongzuoying@sina.com
authors.forename: Zuo-ying
authors.initials: ZY
authors.lastname: Dong
authors.forename: Dong-xu
authors.initials: DX
authors.lastname: Liu
authors.forename: Tie-jun
authors.initials: TJ
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Liu
mesh_terms: D001641:Bicuspid; D003724:Dental Arch / Q000033:anatomy & histology*; D006801:Humans; D008437:Maxilla / Q000033:anatomy & histology; D014081:Tooth Extraction