title: [Study of the crestal bone height and root length technique change of impacted canines treated by modified Nance arch technique].
abstract: OBJECTIVE
  The purpose of this study was to evaluate the crestal bone height and root length change after orthodontic treatment of impacted canines with modified Nance arch technique.
  
  
  METHODS
  8 maxillary impacted canines were treated with modified Nance arch technique. The canines of other side which were naturally erupted were used for self-control. Pre-treatment and post-treatment panoramic radiographs were measured and the following data was collected: (1)The distance of the impacted canine migration and the angle change of the impacted canine; (2)Crestal bone height and root length between previously impacted canines and adjacent lateral incisors and premolars(experimental)and contralateral control teeth. The crestal bone height and root length were compared using a paired t test with SPSS11.0 software package.
  
  
  RESULTS
  The mean distance of the impacted canine migration was 18.43 mm and the mean angle change on the panoramic radiograph was 32.7 degrees. No difference was found in the crestal bone height and the root length between the adjacent lateral incisors and premolars(experimental) and the contralateral control teeth(P>0.05).
  
  
  CONCLUSIONS
  The combination of modified Nance arch with straight wire arch technique is a valid method to treat maxillary impacted canines.
authors.affiliation: Department of Orthodontics, Stomatological Hospital, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China.
authors.forename: Song
authors.initials: S
authors.lastname: Yi
authors.forename: Rong-dang
authors.initials: RD
authors.lastname: Hu
authors.forename: Zhen-yu
authors.initials: ZY
authors.lastname: Ni
authors.forename: Min-ling
authors.initials: ML
authors.lastname: Zheng
authors.forename: Qi
authors.initials: Q
authors.lastname: Lv
mesh_terms: D001641:Bicuspid; D003481:Cuspid; D006801:Humans; D008437:Maxilla; D011862:Radiography, Panoramic; D014078:Tooth Eruption; D014095:Tooth, Impacted