title: Buccally impacted maxillary canines increase the likelihood of root separation in adjacent first premolars.
abstract: OBJECTIVE
  To investigate the influence of maxillary impacted canines on the root morphology of adjacent premolars in a Chinese population.
  
  
  METHODS
  A sample of 370 Chinese subjects with maxillary canine impaction and 370 control subjects were collected in this study. CBCT data of all subjects were collected and analyzed. The prevalence of separate-rooted maxillary premolars was compared between subjects with and without impacted canines. Then, the prevalence of separate-rooted maxillary premolars was compared between subjects with buccal canine impaction (BIC) and those with palatal impaction (PIC).
  
  
  RESULTS
  The prevalence of separate-rooted first premolars was significantly higher in the canine impaction group (P = 0.046), but the prevalence of separate-rooted second premolars was not different (P = 0.780). Furthermore, a significant higher prevalence of first premolar root separation was found on the impacted site in the BIC subgroup (P < 0.001), but not in the PIC subgroup (P = 0.508). Also, the prevalence of separate-rooted first premolars in the BIC subgroup was significantly higher than that of the control group (P = 0.008), but not so for the PIC subgroup (P = 0.097).
  
  
  CONCLUSIONS
  Buccally impacted maxillary canines are associated with an increased prevalence of root separation in the adjacent maxillary first premolars. This is likely because that buccally impacted canines encroach on the space needed for root development of the first premolars.
authors: Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.|Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors: D
authors: D
authors: Cao
authors: Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.|Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors: L
authors: L
authors: Zhu
authors: Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.|Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors: Y
authors: Y
authors: Chen
authors: Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.|Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors: L
authors: L
authors: Xie
authors: Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.|Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors: B
authors: B
authors: Yan
authors: Division of Orthodontics, The Ohio State University, College of Dentistry, Columbus, OH, USA.
authors: Z
authors: Z
authors: Sun
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000002:abnormalities* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D054893:Cone-Beam Computed Tomography; D003481:Cuspid / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014092:Tooth Root / Q000002:abnormalities* / Q000000981:diagnostic imaging; D014095:Tooth, Impacted / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology
keywords: cone-beam computed tomography; impacted canine; premolar; tooth root morphology