title: Evaluation of the root and root canal systems of mandibular first premolars in northern Taiwanese patients using cone-beam computed tomography.
abstract: OBJECTIVE
  Cone-beam computed tomography (CBCT) can provide valuable data for root canal systems of human teeth in vivo. This study used CBCT to evaluate the number of roots and canals of 300 mandibular first premolars in 150 northern Taiwanese patients.
  
  
  METHODS
  The root canal systems of 300 mandibular first premolars in 150 northern Taiwanese patients with bilateral premolars were analyzed by CBCT.
  
  
  RESULTS
  Of the 300 mandibular first premolars, 197 (65.7%) had one root with one canal (1R1C), 49 (16.3%) had one root with two canals (1R2C), 51 (17.0%) had two roots with one canal in each root (2R2C), and three (1.0%) had three roots with one canal in each root (3R3C). Statistical analyses showed that women had a significantly higher incidence of 1R1C mandibular first premolars (71.4%) than men (58.8%, p = 0.031), and men had a significantly higher incidence of 2R2C mandibular first premolars (27.2%) than women (8.5%, p < 0.001). One hundred and twenty-two (81.3%) of the 150 patients had a symmetrical root and root canal system between the right and left mandibular first premolars. Men had a significantly higher symmetrical rate of 2R2C mandibular first premolars (26.5%) than women (8.2%, p = 0.013).
  
  
  CONCLUSIONS
  Approximately 82% of mandibular first premolars in northern Taiwanese patients have one root with either one or two canals. There are significant differences in the number of roots and canals and symmetry of the root canal system of bilateral mandibular first premolars between male and female northern Taiwanese patients.
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Yao-Der
authors.initials: YD
authors.lastname: Huang
authors.affiliation: Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan; Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan.
authors.forename: Jay
authors.initials: J
authors.lastname: Wu
authors.affiliation: Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Rong-Jiun
authors.initials: RJ
authors.lastname: Sheu
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Mu-Hsiung
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Der-Lan
authors.initials: DL
authors.lastname: Chien
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Huang
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Dentistry, Cardinal Tien Hospital, New Taipei City, Taiwan.
authors.forename: Chih-Chia
authors.initials: CC
authors.lastname: Huang
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan; School of Dentistry, National Taiwan University, Taipei, Taiwan. Electronic address: chenyj@ntu.edu.tw.
authors.forename: Yunn-Jy
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001641:Bicuspid / Q000033:anatomy & histology*; D002648:Child; D054893:Cone-Beam Computed Tomography; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008875:Middle Aged; D012390:Root Canal Therapy; D013624:Taiwan; D014092:Tooth Root / Q000033:anatomy & histology*; D055815:Young Adult
keywords: Taiwanese; cone-beam computed tomography; mandibular first premolar; root canal system