title: [Observation of the roots and root canals of 442 maxillary first premolars].
abstract: OBJECTIVE
  To investigate the root and root canal anatomical features of maxillary first premolars in 422 teeth.
  
  
  METHODS
  422 maxillary first premolars were collected to statistically analyze the root types by sex and to observe the root canals by clearing technique; Vertucci's classification was adopted to get the percentage of each root canal type. The data were analyzed with SPSS11.5 software package.
  
  
  RESULTS
  (1)Significant gender difference was found in 422 teeth in terms of the percentage of one root(total 57.36%; male 33.58%; female 62.68%), two roots(total 41.47%; male 62.68%; female 33.33%) and three roots(total 1.18%; male 3.73%; female 0%) (P<0.01). (2)In the 422 transparent specimens of the teeth, totally 9 types of root canals were discovered with the percentage of type I(10.12%), II(10.60%), III(6.02%), IV(56.63%), V(12.05%), VI(1.93%), VII(0.72%), VIII(1.45%), IX(0.48%).
  
  
  CONCLUSIONS
  Understanding of the various and gender-different morphology of the roots and complex root canals of maxillary first premolars, is of great value for the diagnosis and root canal therapy.
authors.affiliation: Department of Endodontics, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China. realcxl@126.com
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Cheng
authors.forename: Yu-Lai
authors.initials: YL
authors.lastname: Weng
mesh_terms: D001641:Bicuspid; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla; D014070:Tooth; D014092:Tooth Root