title: Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study.
abstract: OBJECTIVE
  To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment.
  
  
  METHODS
  Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured.
  
  
  RESULTS
  The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type.
  
  
  CONCLUSIONS
  There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.
authors.affiliation: Department of Stomatology, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Duan
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China. ; Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Deng
authors.affiliation: Department of Stomatology, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Wan-Shan
authors.initials: WS
authors.lastname: Li
authors.affiliation: Department of Otorhinolaryngology, Children's Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Xue-Lei
authors.initials: XL
authors.lastname: Li
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China. ; Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China.
authors.forename: Lei-Lei
authors.initials: LL
authors.lastname: Zheng
authors.affiliation: Department of Stomatology, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Gui-Yuan
authors.initials: GY
authors.lastname: Li
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China. ; Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China.
authors.forename: Yan-Jie
authors.initials: YJ
authors.lastname: Bai
keywords: Cone-beam computed tomography; Mandibular premolar; Tooth position; Vertical facial type