title: The effects of incisor inclination changes on the position of point A in Class II division 2 malocclusion using three-dimensional evaluation: a long-term prospective study.
abstract: OBJECTIVE
  The aim of this study was to evaluate change in the sagittal position of point A due to orthodontic treatment by orthodontic community-cone beam computed tomography (CBCT).
  
  
  METHODS
  40 subjects (22 males and 18 females) who had Class II division 2 malocclusion were recruited, and 40 subjects (23 males and 17 females) who had minor crowding in the beginning of the treatment and required no or minimal maxillary anterior tooth movement were served as control. The changes in maxillary incisor inclination, sagittal position of point A, SNA angle, and movement of incisor root apex and incisal edge were calculated before and after CBCT treatment.
  
  
  RESULTS
  Maxillary incisors were significantly proclined in the study group but not in the control group. This proclination resulted in 2.95 mm backward movement of the root apex and 6.23 mm forward movement of the incisal edge of maxillary incisors. Point A moved 1.24 mm and 0.18 mm backward in the study and control groups, respectively. Incisor root apex and incisal edge almost remained stable in the control group. No significant change was observed in the SNA angle in both the study and control groups. However, the change in SNA between the two groups was found to be significant.
  
  
  CONCLUSIONS
  Proclination of maxillary incisors with backward movement of incisor root apex caused posterior movement of point A. This posterior movement significantly affects the SNA angle.
authors.affiliation: Department of Orthodontics, Hospital of Stomatology, Wenzhou Medical University Wenzhou 325027, China.
authors.forename: Qiushuo
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Orthodontics, Hospital of Stomatology, Wenzhou Medical University Wenzhou 325027, China.
authors.forename: Caixia
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Orthodontics, Hospital of Stomatology, Wenzhou Medical University Wenzhou 325027, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhou
keywords: Class II division 2; maxillary incisor proclination; point A