title: [Evaluation of the prevalence of the maxillary molars with two palatal roots by cone-beam CT].
abstract: OBJECTIVE
  To investigate the characteristic of the maxillary molars with two palatal roots and its prevalence by cone-beam computered tomography.
  
  
  METHODS
  Cone-beam CT (CBCT) images of dentitions were collected retrospectively from 528 patients comprising 1957 maxillary molars. The characteristic and prevalence of maxillary molars with two palatal roots was analyzed. The tooth position, sex and unilateral and bilateral occurrence were recorded.
  
  
  RESULTS
  The prevalence of two palatal roots was 0.72%(14/1957). Maxillary second molar with two palatal roots was detected in 1.12%(11/979), which showed a statistically higher prevalence than maxillary first molar 0.31%(3/978). This prevalence did not differ with sex or the side(P > 0.05). The mean distance of interorifice from the mesiolpalatal canal to the distopalatal canal was (2.84 ± 0.50) mm, and the angle between two palatal roots was on average (34.6 ± 16.1) °,which were significantly greater than the mean distance of interorifice from the two buccal roots (2.15 ± 0.82) mm and the angle between the two roots was (21.3 ± 12.2) °.
  
  
  CONCLUSIONS
  The prevalence of maxillary second molars with two palatal roots was higher than that of the first malars. The angle between the two palatal roots brings difficulty to root canal therapy, so the consciousness of double palatal roots of maxillary molars was helpful for clinical operation.
authors.affiliation: Department of Operative Dentistry and Endodontic, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Qun
authors.initials: Q
authors.lastname: Lu
authors.forename: Qing-xia
authors.initials: QX
authors.lastname: Bai
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiao-jing
authors.initials: XJ
authors.lastname: Liu
authors.forename: Zhao-juan
authors.initials: ZJ
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging; D008875:Middle Aged; D008963:Molar / Q000000981:diagnostic imaging*; D015995:Prevalence; D012189:Retrospective Studies; D019227:Tooth Apex / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D055815:Young Adult