title: Root and canal morphology of maxillary first premolars in a Chinese subpopulation evaluated using cone-beam computed tomography.
abstract: OBJECTIVE
  To evaluate the external and internal anatomy of maxillary first premolar teeth in a Chinese subpopulation using cone-beam computed tomography (CBCT).
  
  
  METHODS
  A total of 300 CBCT images involving maxillary first premolar teeth were obtained from 241 patients who underwent CBCT scanning as part of an oral and dental examination for bone mass before placement of implants or to locate impacted teeth before orthodontic therapy. Tooth position, number of roots, canal configuration, number of canals and number of apical foramina per root were investigated. The Fisher's exact test was used to analyse the correlation between root number and tooth position.
  
  
  RESULTS
  Overall, 66% (n = 198) of teeth had one root and 33% (n = 100) had two roots; the remaining 1% (n = 2) had three roots. This frequency distribution showed no statistical significance between left and right sides. The most frequent canal configuration of these maxillary first premolars was type IV (n = 153; 51%), followed by type II (n = 70; 23%), with only 1% (n = 2) of teeth having type VIII. One-rooted teeth with canal bifurcations and/or combinations (types II, III, V, VI and VII) accounted for nearly 50% (n = 98) of the sample. Eighty-five per cent (n = 255) of the teeth examined had two root canals (types II-VII), and 14% (n = 43) had one. Amongst the 59 patients with bilateral teeth, 38 had a symmetrical pattern of tooth anatomy, including the same number of roots and the same types of canal configurations.
  
  
  CONCLUSIONS
  There was a high frequency of one-rooted teeth amongst maxillary first premolars, with most having one root with two canals (types II-VII). The morphology of the canal in one-rooted teeth was highly variable.
authors.affiliation: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Tian
authors.forename: B
authors.initials: B
authors.lastname: Guo
authors.forename: R
authors.initials: R
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Yu
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Hu
authors.forename: P M H
authors.initials: PM
authors.lastname: Dummer
mesh_terms: D063405:Anatomic Variation; D044466:Asian People; D001641:Bicuspid / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D016009:Chi-Square Distribution; D002681:China; D054893:Cone-Beam Computed Tomography; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008437:Maxilla; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging