Imaging Sci Dent.  2011 Jun;41(2):79-84. 10.5624/isd.2011.41.2.79.

Determination of midsagittal plane for evaluation of facial asymmetry using three-dimensional computed tomography

• Kim TY
• Baik JS
• Park JY
• Chae HS
• Huh KH
• Choi SC

• KMID: 1449939
• DOI: http://doi.org/10.5624/isd.2011.41.2.79

Abstract

PURPOSE
The aim of the present study was to investigate the disagreement of cephalometric analysis depending on the reference determination of midsagittal plane on three-dimensional computed tomography.
MATERIALS AND METHODS
A total of 102 young women with class III dentofacial deformity were evaluated using three-dimensional computed tomography. The cranial and facial midsagittal planes were defined and the amounts of jaw deviation were calculated. The amounts of jaw deviation were compared with paired t-test (2-tailed) and Bland-Altman plot was drawn.
RESULTS
The landmark tracing were reproducible (r> or =.978). The jaws relative to the cranial midsagittal plane were 10-17 times more significantly deviated than to the facial midsagittal plane (P<.001). Bland-Altman plot demonstrated that the differences between the amounts of jaw deviation from two midsagittal planes were not normally distributed versus the average of the amounts of jaw deviation from two midsagittal planes.
CONCLUSION
The cephalometric analyses of facial asymmetry were significantly inconsistent depending on the reference determination of midsagittal plane. The reference for midsagittal plane should be carefully determined in three-dimensional cephalometric analysis of facial asymmetry of patients with class III dentofacial deformity.

Keyword

Cephalometry; Facial Asymmetry; Tomography, X-Ray Computed; Imaging Three-Dimensional

MeSH Terms

Cephalometry
Dentofacial Deformities
Facial Asymmetry
Female
Humans
Jaw
Tomography, X-Ray Computed

Figure

• 

  Fig. 1 Landmarks and jaw deviation. A. The jaw deviation is determined as a perpendicular distance between midpoint (ANS and GT) and midsagittal plane (MSP), B. The averaged points of foramina ovale (FO) and foramina spinosum (FS) on both sides are depicted.

• 

  Fig. 2 Bland-Altman plot for jaw deviation to two midsagittal planes (MSP). The x-axis indicates the average (mm) of DCs and DFs, whereas the y-axis indicates the difference (mm) between DCs and DFs. The limits of agreement (mean difference±2 SD) are graphed by the horizontal lines. A. For the maxillary deviation, B. For the mandibular deviation. Both plots demonstrate the DCs and DFs are not normally distributed by the Bland-Altman method. This means DCs are larger than DFs as the jaw midpoints (ANS and GT) are distant from the MSP.

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