title: Factors influencing the non-surgical eruption of palatally impacted canines.
abstract: BACKGROUND
  Many palatally impacted canines in children do not require surgical exposure prior to the start of orthodontic treatment. They erupt in mid-alveolar positions providing excess space is made for them in the arch. The time required for an impacted tooth to emerge under these conditions is highly variable.
  
  
  OBJECTIVE
  To determine the factors influencing the time required for a palatally impacted canine to spontaneously disimpact following orthodontic treatment to create excess space in the arch.
  
  
  METHODS
  Thirty palatally impacted canines, which emerged following orthodontic treatment to open excess space in the arch, were used. The impacted teeth were present in 28 children. No canines were surgically exposed. The positions of the impacted canines before treatment, the mesiodistal widths and rotations of the adjacent and contralateral lateral incisors, age and gender of the subjects, subjects' dental ages, presence of either incisor or premolar hypodontia, number of subjects with bilaterally impacted canines, and number of siblings with impacted canines were recorded. Canines that erupted in less than nine months of treatment were compared with canines that required more than nine months of treatment. The canines were grouped by severity of impaction (sectors II - IV) and compared.
  
  
  RESULTS
  There were significantly more severe (sector IV) impactions in the long duration group compared with the short duration group. Significantly more cases of incisor-premolar hypodontia were found in the short duration group. Canines impacted in sector IV emerged after 21 months of treatment and canines in sectors II and III emerged after eight months of treatment. Lateral incisors adjacent to the impacted teeth were rotated mesiolabially to a greater extent in the sector IV group compared with lateral incisors in the sector II group. Differences in rotation of the adjacent and contralateral lateral incisors were significantly less in the sector II group compared with the lateral incisors in the sector III and IV groups.
  
  
  CONCLUSIONS
  The sector of impaction was the best guide to the duration of treatment prior to emergence.
authors.affiliation: r.h.olive@uq.net.au r.h.olive@uq.net.au
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Olive
mesh_terms: D000293:Adolescent; D000366:Age Determination by Teeth; D000367:Age Factors; D000848:Anodontia / Q000473:pathology; D001641:Bicuspid / Q000002:abnormalities; D002648:Child; D003481:Cuspid / Q000473:pathology*; D003724:Dental Arch / Q000473:pathology; D005260:Female; D006801:Humans; D007180:Incisor / Q000002:abnormalities / Q000473:pathology; D008297:Male; D010159:Palate; D012399:Rotation; D012737:Sex Factors; D013997:Time Factors; D019237:Tooth Cervix / Q000473:pathology; D014078:Tooth Eruption; D014087:Tooth Movement Techniques / Q000379:methods*; D014092:Tooth Root / Q000473:pathology; D014095:Tooth, Impacted / Q000145:classification / Q000235:genetics / Q000628:therapy*