Korean J Orthod.  2011 Apr;41(2):87-97. 10.4041/kjod.2011.41.2.87.

The relationship between condyle position, morphology and chin deviation in skeletal Class III patients with facial asymmetry using cone-beam CT

• Lee BR
• Kang DK
• Son WS
• Park SB
• Kim SS
• Kim YI
• Lee KM

• KMID: 2274245
• DOI: http://doi.org/10.4041/kjod.2011.41.2.87

Abstract

OBJECTIVE
Facial asymmetry is usually evaluated from the difference in length and angulation of the maxilla and mandible. However, asymmetric position or shape of the condyle can also affect the expression of asymmetry. The purpose of this study was to evaluate the correlation between condylar asymmetry and chin point deviation in facial asymmetry.
METHODS
Cone-beam CT images of fifty adult skeletal Class III patients were studied. Thirty patients who had more than 4 mm menton deviation were categorized in the asymmetric group. Twenty patients with less than 4 mm menton deviation were assigned to the symmetric group. Anteroposterior and transverse condyle positions were evaluated from the cranial base. The greatest mediolateral diameter (GMD) of the condyle in the axial plane and angulation to the coronal plane were measured. The height and volume of the condyles were evaluated.
RESULTS
The symmetric group had no statistical difference between both condyles in position, angulation, GMD, height and volume. In the asymmetric group, the non-deviated side condyle was larger in GMD, height and volume than the deviated side. There was no statistical difference in condyle position and angulation. The GMD, height difference and condylar volume ratio (non-deviated/deviated) were positively correlated with chin deviation. From the linear regression analysis, condylar volume ratio was a significant factor affecting chin deviation.
CONCLUSIONS
These findings suggests that the non-deviated side condyle is larger than the deviated side. In addition, condylar asymmetry can affect the expression of facial asymmetry.

Keyword

Facial asymmetry; Cone-beam computed tomography; Mandibular condyle; Menton deviation

MeSH Terms

Adult
Chin
Cone-Beam Computed Tomography
Facial Asymmetry
Humans
Linear Models
Mandible
Mandibular Condyle
Maxilla
Skull Base

Figure

• 

  Fig. 1 Reference planes and chin point deviation. A, Constructed reference planes; B, chin point deviation measured from MSR plane to menton point (inferior).

• 

  Fig. 2 Measurement of GMD, angulation to coronal plane. The geometric center defined as the center of GMD. The anteroposterior position to coronal plane and mediolateral position to midsagittal reference plane of geometric center were measured. GMD, Greateast mediolateral diameter; AP, anteroposterior; ML, mediolateral; MSR plane, midsagittal reference plane.

• 

  Fig. 3 Measurement of condylar height. A, Center of ramus. This line bisects the axial plane of ramus; B, ramal plane was constructed by a line perpendicular to the center of ramus and tangent to the posterior ramus. PR (Perpendicular to ramal) plane, a line passing through the deepest point of sigmoid notch and tagent to the ramal plane. Condylar height was measured from the PR plane to the highest point of the condyle (parallel to ramal plane).

• 

  Fig. 4 Condyle segmentation was done for condylar volume measurement.

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