Imaging Sci Dent.  2015 Dec;45(4):227-232. 10.5624/isd.2015.45.4.227.

The location of midfacial landmarks according to the method of establishing the midsagittal reference plane in three-dimensional computed tomography analysis of facial asymmetry

• Kim MS
• Lee EJ
• Song IJ
• Lee JS
• Kang BC
• Yoon SJ

• KMID: 2132935
• DOI: http://doi.org/10.5624/isd.2015.45.4.227

Abstract

PURPOSE
The purpose of this study was to evaluate the influence of methods of establishing the midsagittal reference plane (MRP) on the locations of midfacial landmarks in the three-dimensional computed tomography (CT) analysis of facial asymmetry.
MATERIALS AND METHODS
A total of 24 patients (12 male and 12 female; mean age, 22.5 years; age range, 18.2-29.7 years) with facial asymmetry were included in this study. The MRP was established using two different methods on each patient's CT image. The x-coordinates of four midfacial landmarks (the menton, nasion, upper incisor, and lower incisor) were obtained by measuring the distance and direction of the landmarks from the MRP, and the two methods were compared statistically. The direction of deviation and the severity of asymmetry found using each method were also compared.
RESULTS
The x-coordinates of the four anatomic landmarks all showed a statistically significant difference between the two methods of establishing the MRP. For the nasion and lower incisor, six patients (25.0%) showed a change in the direction of deviation. The severity of asymmetry also changed in 16 patients (66.7%).
CONCLUSION
The results of this study suggest that the locations of midfacial landmarks change significantly according to the method used to establish the MRP.

Keyword

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

MeSH Terms

Anatomic Landmarks
Facial Asymmetry*
Female
Humans
Incisor
Male
Tomography, X-Ray Computed

Figure

• 

  Fig. 1 The establishment of the midsagittal reference plane by two methods. A. In Method 1, the horizontal reference plane is established using the PoR, PoL, and OrL landmarks, the midsagittal reference plane (MRP) by using the Cg and P, and the coronal reference plane by using the Op. The planes are perpendicular to one another. B. In Method 2, the Op, Cg, and ANS landmarks identified in Method 1 are used to establish the MRP. Midfacial landmarks are indicated as circles, and the MRP is shown as a black vertical line. PoR: right porion, PoL: left porion, OrL: left orbitale, Cg: crista galli, P: prechiasmatic groove, Op: opisthion, ANS: anterior nasal spine.

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