title: A comparative study of the deviation of the menton on posteroanterior cephalograms and three-dimensional computed tomography.
abstract: OBJECTIVE
  Facial asymmetry has been measured by the severity of deviation of the menton (Me) on posteroanterior (PA) cephalograms and three-dimensional (3D) computed tomography (CT). This study aimed to compare PA cephalograms and 3D CT regarding the severity of Me deviation and the direction of the Me.
  
  
  METHODS
  PA cephalograms and 3D CT images of 35 patients who underwent orthognathic surgery (19 males and 16 females, with an average age of 22.1±3.3 years) were retrospectively reviewed in this study. By measuring the distance and direction of the Me from the midfacial reference line and the midsagittal plane in the cephalograms and 3D CT, respectively, the x-coordinates (x1 and x2) of the Me were obtained in each image. The difference between the x-coordinates was calculated and statistical analysis was performed to compare the severity of Me deviation and the direction of the Me in the two imaging modalities.
  
  
  RESULTS
  A statistically significant difference in the severity of Me deviation was found between the two imaging modalities (Δx=2.45±2.03 mm, p<0.05) using the one-sample t-test. Statistically significant agreement was observed in the presence of deviation (k=0.64, p<0.05) and in the severity of Me deviation (k=0.27, p<0.05). A difference in the direction of the Me was detected in three patients (8.6%). The severity of the Me deviation was found to vary according to the imaging modality in 16 patients (45.7%).
  
  
  CONCLUSIONS
  The measurement of Me deviation may be different between PA cephalograms and 3D CT in some patients.
authors.affiliation: School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Sungeun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Oral Anatomy, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Lee
authors.affiliation: Department of Nursing, Kwangju Women's University, Gwangju, Korea.
authors.forename: In Ja
authors.initials: IJ
authors.lastname: Song
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, 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 Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Hoi-Jeong
authors.initials: HJ
authors.lastname: Lim
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
keywords: Anatomic Landmarks; Facial Asymmetry; Tomography, X-Ray Computed