title: Analysis of the Root and Canal Morphologies in Maxillary First and Second Molars in a Chinese Population Using Cone-beam Computed Tomography.
abstract: BACKGROUND
  We analyzed and characterized the root and canal morphologies in maxillary first and second molars in a large sample of Chinese patients using reconstructed cone-beam computed tomographic (CBCT) imaging.
  
  
  METHODS
  Maxillary first (n = 1558) and second (n = 1539) molars were collected from Chinese patients (N = 844) who had undergone in vivo CBCT imaging. The root canal number and morphology were determined according to Vertucci's classification.
  
  
  RESULTS
  A single root was found in 0.06% of first molars, which showed type I canal systems. However, second molars with a single root (4.2%) showed widely varied canal systems. The buccal roots of first molars with 2 separate roots showed type I, II, or III canal systems, whereas those of 2-rooted second molars showed widely varied canal systems. The incidence of fused roots was 1.38% for first molars and 23.9% for second molars, whereas canal fusion within fused roots was observed in 4.5% of first molars and 10.6% of second molars. Additional canals were observed in 67.8% and 29.7% of mesiobuccal roots, 1.8% and 0.7% of distobuccal roots, and 0.7% and 0.3% of palatal roots in 1523 and 1017 first and second molars with 3 separate roots, respectively. The mesiobuccal root canal number showed bilateral symmetry between 79% of first molars and 82.3% of second molars, with a concurrence rate of 59.8% between adjacent molars.
  
  
  CONCLUSIONS
  We reported the root and canal morphologic variations in maxillary first and second molars, which have not been reported for Chinese populations. Further studies should focus on canals in fused roots and mesiobuccal roots.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Tian
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China.
authors.forename: Xiang-Wen
authors.initials: XW
authors.lastname: Yang
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Qian
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China; Stomatology Special Consultation Clinic, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China. Electronic address: weibin0328@hotmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.affiliation: Department of Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Huangpu District, Shanghai, China. Electronic address: gongyao0328@hotmail.com.
authors.forename: Yao
authors.initials: Y
authors.lastname: Gong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008875:Middle Aged; D008963:Molar / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Canal morphology; cone-beam computed tomography; maxillary molars; root morphology