title: Influence of patient head positioning on measured axial tooth inclination in panoramic radiography.
abstract: OBJECTIVE
  Panoramic radiographs are routinely used to assess the mesiodistal axial inclination of teeth (MDAI) in orthodontic treatment. These radiographs are sensitive to minor deviations from standard head position that result in image distortions. The aim of this study is to measure and quantify the changes in MDAI on panoramic radiograph resulting from changes in patient head position.
  
  
  METHODS
  The testing devise was a human skull with guide wires placed on the facial surface of the teeth and alveolar process along the long axis of each tooth. Panoramic radiographs were captured digitally with the orientation of the skull in Frankfurt horizontal plane parallel to the floor and with 1 degrees , 2 degrees , 5 degrees , 7 degrees , and 10 degrees both superior and inferior rotations. The mesiodistal tooth angulations were determined using MIPAC software (DentalEye and LEAD Technologies, Inc. 2005).
  
  
  RESULTS
  The more distal the position of the tooth in the arch the greater the change in MDAI with a change in vertical head position. A maximum change of approximately 10 degrees was observed in MDAI of both the maxillary and mandibular molars with a corresponding superior head tilt of 10 degrees. The Mandibular anteriors displayed significant inconsistencies in MDAI with both superior and inferior head tilt. A superior head tilt produced a greater change in mesiodistal angulation than did an inferior head tilt.
  
  
  CONCLUSIONS
  Accurately taken panoramic radiographs can serve as a convenient tool for evaluating the MDAI before, during and after orthodontic treatment. Additional radiographs are recommended for the mandibular anteriors.
authors.affiliation: Tufts University School of Dental Medicine, 1 Kneeland Street, Boston, MA 02111, USA. tictac2@gmail.com
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Hardy
authors.forename: Lokesh
authors.initials: L
authors.lastname: Suri
authors.forename: Paul
authors.initials: P
authors.lastname: Stark
mesh_terms: D003481:Cuspid / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D003724:Dental Arch / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D007180:Incisor / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008334:Mandible / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009811:Odontometry / Q000706:statistics & numerical data*; D011187:Posture; D011856:Radiographic Image Enhancement; D011862:Radiography, Panoramic / Q000706:statistics & numerical data*; D014070:Tooth / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging