title: Deviation of landmarks in accordance with methods of establishing reference planes in three-dimensional facial CT evaluation.
abstract: OBJECTIVE
  This study aimed to investigate the deviation of landmarks from horizontal or midsagittal reference planes according to the methods of establishing reference planes.
  
  
  METHODS
  Computed tomography (CT) scans of 18 patients who received orthodontic and orthognathic surgical treatment were reviewed. Each CT scan was reconstructed by three methods for establishing three orthogonal reference planes (namely, the horizontal, midsagittal, and coronal reference planes). The horizontal (bilateral porions and bilateral orbitales) and midsagittal (crista galli, nasion, prechiasmatic point, opisthion, and anterior nasal spine) landmarks were identified on each CT scan. Vertical deviation of the horizontal landmarks and horizontal deviation of the midsagittal landmarks were measured.
  
  
  RESULTS
  The porion and orbitale, which were not involved in establishing the horizontal reference plane, were found to deviate vertically from the horizontal reference plane in the three methods. The midsagittal landmarks, which were not used for the midsagittal reference plane, deviated horizontally from the midsagittal reference plane in the three methods.
  
  
  CONCLUSIONS
  In a three-dimensional facial analysis, the vertical and horizontal deviations of the landmarks from the horizontal and midsagittal reference planes could vary depending on the methods of establishing reference planes.
authors.affiliation: School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Kaeng Won
authors.initials: KW
authors.lastname: Yoon
authors.affiliation: Department of Oral and Maxillofacial Radiology, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Suk-Ja
authors.initials: SJ
authors.lastname: Yoon
authors.affiliation: Department of Oral and Maxillofacial Radiology, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Byung-Cheol
authors.initials: BC
authors.lastname: Kang
authors.affiliation: Department of Oral and Maxillofacial Radiology, Hallym University Sacred Heart Hospital, Anyang, Korea.
authors.forename: Young-Hee
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Min Suk
authors.initials: MS
authors.lastname: Kook
authors.affiliation: Department of Oral and Maxillofacial Radiology, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Jae-Seo
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Orthodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Juan Martin
authors.initials: JM
authors.lastname: Palomo
keywords: Facial Asymmetry; Orthognathic Surgery; Tomography, X-Ray Computed