Korean J Orthod.  2014 Mar;44(2):62-68. 10.4041/kjod.2014.44.2.62.

Three-dimensional symmetry and parallelism of the skeletal and soft-tissue poria in patients with facial asymmetry

• Kim MG
• Lee JW
• Cha KS
• Chung DH
• Lee SM

• KMID: 2273428
• DOI: http://doi.org/10.4041/kjod.2014.44.2.62

Abstract

OBJECTIVE
The purpose of this study was to examine the symmetry and parallelism of the skeletal and soft-tissue poria by three-dimensional (3D) computed tomographic (CT) imaging.
METHODS
The locations of the bilateral skeletal and soft-tissue poria in 29 patients with facial asymmetry (asymmetric group) and 29 patients without facial asymmetry (symmetric group) were measured in 3D reconstructed models of CT images by using a 3D coordinate system. The mean intergroup differences in the anteroposterior and vertical angular deviations of the poria and their anteroposterior and vertical parallelism were statistically analyzed.
RESULTS
The symmetric and asymmetric groups showed significant anteroposterior angular differences in both the skeletal and the soft-tissue poria (p = 0.007 and 0.037, respectively; Mann-Whitney U-test). No significant differences in the anteroposterior and vertical parallelism of the poria were noted (p < or = 0.05; Wilcoxon signed-rank test).
CONCLUSIONS
In general, the skeletal poria are parallel to the soft-tissue poria. However, patients with facial asymmetry tend to have asymmetric poria.

Keyword

Computed tomography; Soft tissue; Anatomy; Facial asymmetry; Porion; Parallelism

MeSH Terms

Facial Asymmetry*
Humans
Poria*

Figure

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  Figure 1 Parallelism of the skeletal and soft-tissue poria. A, Vertical parallelism; B, anteroposterior parallelism.

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  Figure 2 The three-dimensional (3D) reconstructed model. A, 3D reconstruction of computed tomographic images; B, 3D coordinate system.

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  Figure 3 Measurement of the angular deviations. A, Anteroposterior deviation (θ1); B, vertical deviation (θ2).a, l x coordinate of left porion - x coordinate of right porion l; b, l z coordinate of left porion - z coordinate of right porion l; c, l y coordinate of left porion - y coordinate of right porion l.

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  Figure 4 Receiver operating characteristic (ROC) curves of θsk1 and θsof1. a, cutoff section of θsk1; b, cutoff section of θsof1.

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  Figure 5 Conversion of angular deviation into linear deviation. A, For the skeletal poria; B, for the soft-tissue poria.

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