title: Accuracy and head positioning effects on measurements of anterior tooth length using 3-dimensional and conventional dental panoramic radiography.
abstract: BACKGROUND
  The purposes of this study were to examine the accuracy and the head positioning effects on measurements of anterior tooth length using 3-dimensional (3D) and conventional dental panoramic radiography and to investigate whether 3D panoramic radiography is suitable for the evaluation of anterior tooth length.
  
  
  METHODS
  A simulated human head was radiographed at 4, 8, and 12 mm displaced positions, and at 5°, 10°, and 15° tilted positions from the standard head position using 3D and conventional panoramic radiography, and also using cone-beam computed tomography. Anterior tooth lengths were measured on the panoramic and cone-beam computed tomography images. The values for the standard head position in the panoramic radiographs were defined as the standard values. Measurement error was defined as the standard value minus the cone-beam computed tomography value on each panoramic radiograph. The head position ratio of the measurement value to the standard value at each head position was calculated.
  
  
  RESULTS
  Measurement errors for the 3D panoramic radiographs were significantly smaller than those for the conventional panoramic radiographs. In the 3D panoramic radiographs, the head position ratios at the 4, 8, and 12 mm displaced positions and at the 5° tilted position were within ±5% of the standard value.
  
  
  CONCLUSIONS
  Three-dimensional panoramic radiography is suitable for the quantitative evaluation of anterior tooth length with high accuracy.
authors.affiliation: Department of Orthodontics, School of Dentistry, Asahi University, Mizuho, Gifu, Japan. Electronic address: nkitai@dent.asahi-u.ac.jp.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kitai
authors.affiliation: Department of Orthodontics, School of Dentistry, Asahi University, Mizuho, Gifu, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Murabayashi
authors.affiliation: Department of Orthodontics, School of Dentistry, Asahi University, Mizuho, Gifu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sugimoto
authors.affiliation: Department of Orthodontics, School of Dentistry, Asahi University, Mizuho, Gifu, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fujiwara
authors.affiliation: Department of Orthodontics, School of Dentistry, Asahi University, Mizuho, Gifu, Japan.
authors.forename: Wakako
authors.initials: W
authors.lastname: Tome
authors.affiliation: Department of Oral Radiology, School of Dentistry, Asahi University, Mizuho, Gifu, Japan.
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Katsumata
mesh_terms: D054893:Cone-Beam Computed Tomography; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011862:Radiography, Panoramic / Q000379:methods*