title: Reproducibility of landmark identification in the jaw and teeth on 3-dimensional cone-beam computed tomography images.
abstract: OBJECTIVE
  To compare the reproducibility of landmark identification on three-dimensional (3D) cone-beam computed tomography (CBCT) images between procedures based on traditional cephalometric definitions (procedure 1) and those tentatively proposed for 3D images (procedure 2).
  
  
  METHODS
  A phantom with embedded dried human skull was scanned using CBCT. The acquired volume data were transferred to a personal computer, and 3D images were reconstructed. Eighteen dentists plotted nine landmarks related to the jaws and teeth four times: menton (Me), pogonion (Po), upper-1 (U1), lower-1 (L1), left upper-6 (U6), left lower-6 (L6), gonion (Go), condyle (Cd), and coronoid process (Cp). The plotting reliabilities of the two procedures were compared by calculating standard deviations (SDs) in three components (x, y, and z) of coordinates and volumes of 95% confidence ellipsoid.
  
  
  RESULTS
  All 27 SDs for procedure 2 were less than 1 mm, and only five of them exceeded 0.5 mm. The variations were significantly different between the two procedures, and the SDs of procedure 2 were smaller than those of procedure 1 in 21 components of coordinates. The ellipsoid volumes were also smaller for procedure 2 than procedure 1, although a significant difference was not found.
  
  
  CONCLUSIONS
  Definitions determined strictly on each three sectional images, such as for procedure 2, were required for sufficient reliability in identifying the landmark related to the jaws and teeth.
authors.affiliation: Department of Orthodontics, Aichi-Gakuin University School of Dentistry, Nagoya, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Fuyamada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nawa
authors.forename: Momoko
authors.initials: M
authors.lastname: Shibata
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Yoshida
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kise
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Katsumata
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Ariji
authors.forename: Shigemi
authors.initials: S
authors.lastname: Goto
mesh_terms: D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D002508:Cephalometry / Q000379:methods; D002680:Chin / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007180:Incisor / Q000000981:diagnostic imaging; D008334:Mandible / Q000000981:diagnostic imaging*; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging*; D008963:Molar / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D014070:Tooth / Q000000981:diagnostic imaging*