title: Arch width changes in patients with Class II division 1 malocclusion treated with maxillary first premolar extraction and non-extraction method.
abstract: BACKGROUND
  The aim of this study was to determine arch width changes during maxillary first premolars extraction and non-extraction treatment in patients with Class II division 1 malocclusion.
  
  
  METHODS
  Dental casts of 91 Class II division 1 patients (36 males and 55 females) were evaluated. The minimum age of the subjects at the beginning of treatment was above 16 years. 48 patients were treated with extraction of the maxillary first premolars and 43 patients were treated without extraction. Pre- and post-treatment maxillary and mandibular inter-canine and inter-molar arch widths were measured.
  
  
  RESULTS
  At the end of treatment, maxillary and mandibular inter-canine widths of both groups increased significantly. The maxillary inter-molar width decreased in the extraction group and increased in the non-extraction group. The mandibular inter-molar width increased significantly in both groups. No significant differences were observed between males and females.
  
  
  CONCLUSIONS
  The results of this study indicated that there was a tendency for an increase in arch width during both the extraction and non-extraction treatment except maxillary inter-molar width in the extraction cases.Key words:Dental arch, malocclusion, angle Class II, tooth movement, extraction.
authors.affiliation: Lecturer and Faculty Member, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran; Research Fellow, Dental and Periodontal Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Sajjad
authors.initials: S
authors.lastname: Shirazi
authors.affiliation: Associate Professor, Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Mojgan
authors.initials: M
authors.lastname: Kachoei
authors.affiliation: Post Graduate Student, Department of Pediatric Dentistry, Faculty of Dentistry, Tabriz University of Medical Science, Tabriz, Iran.
authors.forename: Naiemeh
authors.initials: N
authors.lastname: Shahvaghar-Asl
authors.affiliation: Under Graduate Student, Student Research Committee, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Samaneh
authors.initials: S
authors.lastname: Shirazi
authors.affiliation: Assistant Professor of Orthodontics, Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Sharghi