title: The impact of reorienting cone-beam computed tomographic images in varied head positions on the coordinates of anatomical landmarks.
abstract: OBJECTIVE
  The aim of this study was to compare the coordinates of anatomical landmarks on cone-beam computed tomographic (CBCT) images in varied head positions before and after reorientation using image analysis software.
  
  
  METHODS
  CBCT images were taken in a normal position and four varied head positions using a dry skull marked with 3 points where gutta percha was fixed. In each of the five radiographic images, reference points were set, 20 anatomical landmarks were identified, and each set of coordinates was calculated. Coordinates in the images from the normally positioned head were compared with those in the images obtained from varied head positions using statistical methods. Post-reorientation coordinates calculated using a three-dimensional image analysis program were also compared to the reference coordinates.
  
  
  RESULTS
  In the original images, statistically significant differences were found between coordinates in the normal-position and varied-position images. However, post-reorientation, no statistically significant differences were found between coordinates in the normal-position and varied-position images.
  
  
  CONCLUSIONS
  The changes in head position impacted the coordinates of the anatomical landmarks in three-dimensional images. However, reorientation using image analysis software allowed accurate superimposition onto the reference positions.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul, Korea.
authors.forename: Jae Hun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul, Korea.
authors.forename: Ho-Gul
authors.initials: HG
authors.lastname: Jeong
authors.affiliation: Department of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul, Korea.
authors.forename: Jae Joon
authors.initials: JJ
authors.lastname: Hwang
authors.affiliation: Department of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul, Korea.
authors.forename: Jung-Hee
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul, Korea.
authors.forename: Sang-Sun
authors.initials: SS
authors.lastname: Han
keywords: Anatomic Landmarks; Cone-Beam Computed Tomography; Orthodontics