Imaging Sci Dent.  2016 Mar;46(1):33-38. 10.5624/isd.2016.46.1.33.

A comparative study of the deviation of the menton on posteroanterior cephalograms and three-dimensional computed tomography

• Lee HJ
• Lee S
• Lee EJ
• Song IJ
• Kang BC
• Lee JS
• Lim HJ
• Yoon SJ

• KMID: 2160155
• DOI: http://doi.org/10.5624/isd.2016.46.1.33

Abstract

PURPOSE
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.
MATERIALS AND 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%).
CONCLUSION
The measurement of Me deviation may be different between PA cephalograms and 3D CT in some patients.

Keyword

Facial Asymmetry; Anatomic Landmarks; Tomography, X-Ray Computed

MeSH Terms

Anatomic Landmarks
Facial Asymmetry
Female
Humans
Male
Orthognathic Surgery
Retrospective Studies
Tomography, X-Ray Computed

Figure

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  Fig. 1 Menton deviation as measured on the posteroranterior (PA) cephalogram (x1) and three-dimensional computed tomography (3D CT) (x2) of one patient. A. Menton deviation (x1) was measured from the midfacial line on the PA cephalogram. B. Menton deviation (x2) is measured from the midsagittal reference plane on 3D CT. C. Three orthogonal planes are established on 3D CT.

• 

  Fig. 2 Bland-Altman difference plot for analyzing the agreement between posteroranterior cephalograms and computed tomography.

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