Korean J Orthod.  2017 May;47(3):195-206. 10.4041/kjod.2017.47.3.195.

Targeted presurgical decompensation in patients with yaw-dependent facial asymmetry

• Kim KA
• Lee JW
• Park JH
• Kim BH
• Ahn HW
• Kim SJ

• KMID: 2379653
• DOI: http://doi.org/10.4041/kjod.2017.47.3.195

Abstract

Facial asymmetry can be classified into the rolling-dominant type (R-type), translation-dominant type (T-type), yawing-dominant type (Y-type), and atypical type (A-type) based on the distorted skeletal components that cause canting, translation, and yawing of the maxilla and/or mandible. Each facial asymmetry type represents dentoalveolar compensations in three dimensions that correspond to the main skeletal discrepancies. To obtain sufficient surgical correction, it is necessary to analyze the main skeletal discrepancies contributing to the facial asymmetry and then the skeletal-dental relationships in the maxilla and mandible separately. Particularly in cases of facial asymmetry accompanied by mandibular yawing, it is not simple to establish pre-surgical goals of tooth movement since chin deviation and posterior gonial prominence can be either aggravated or compromised according to the direction of mandibular yawing. Thus, strategic dentoalveolar decompensations targeting the real basal skeletal discrepancies should be performed during presurgical orthodontic treatment to allow for sufficient skeletal correction with stability. In this report, we document targeted decompensation of two asymmetry patients focusing on more complicated yaw-dependent types than others: Y-type and A-type. This may suggest a clinical guideline on the targeted decompensation in patient with different types of facial asymmetries.

Keyword

Facial asymmetry; Decompensation; Orthognathic surgery; Mandibular yaw

MeSH Terms

Chin
Facial Asymmetry*
Humans
Mandible
Maxilla
Orthognathic Surgery
Tooth Movement

Figure

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  Figure 1 Characteristic and targeted decompensation according to facial asymmetry types.

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  Figure 2 Pretreatment cephalometric and cone-beam computed tomography analyses of a patient (Case 1) with a yawing-dominant type asymmetry. A, Three-dimensional volume-rendering frontal image; B, axial image; C, lateral cephalograph; D, panoramic radiograph; E, cephalometric measurements.Refer to Table 2 for the definitions of each measurement.

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  Figure 3 Pretreatment photographs of a patient (Case 1) with a yawing-dominant type asymmetry.

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  Figure 4 Pretreatment cephalometric and cone-beam computed tomography analyses of a patient (Case 2) with an atypical type asymmetry. A, Three-dimensional volume-rendering frontal image; B, axial image; C, lateral cephalograph; D, panoramic radiograph; E, cephalometric measurements.Refer to Table 2 for the definitions of each measurement.

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  Figure 5 Pretreatment photographs of a patient (Case 2) with an atypical type asymmetry.

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  Figure 6 Presurgical intraoral photographs of a patient (Case 1) with a yawing-dominant type asymmetry, and three-dimensional superimposition of the initial and presurgical mandibular models. Gray color, initial mandibular model; green color, pre-surgical mandibular model.

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  Figure 7 Presurgical three-dimensional volume-rendering frontal (A,) axial images (B,) and lateral cephalograph (C) of a patient (Case 1) with a yawing-dominant type asymmetry.

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  Figure 8 Presurgical intraoral photographs of a patient (Case 2) with an atypical type asymmetry, and three-dimensional superimposition of the initial and presurgical mandibular models. Gray color, initial mandibular model; green color, presurgical mandibular model.

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  Figure 9 Presurgical three-dimensional volume-rendering frontal (A,) axial images (B,) and lateral cephalograph (C) of a patient (Case 2) with an atypical type asymmetry.

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  Figure 10 Post-treatmet cephalometric and cone-beam computed tomography images of a patient (Case 1) with a yawing-dominant type asymmetry. A, Three-dimensional volume-rendering frontal image; B, axial image; C, lateral cephalograph; D, panoramic radiograph; E, superim-position (black color, initial; blue color, presurgical; red color, post-treatment).

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  Figure 11 Post-treatment photographs of a patient (Case 1) with a yawing-dominant type asymmetry.

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  Figure 12 Post-treatmet cephalometric and cone-beam computed tomography images of a patient (Case 2) with an atypical type asymmetry: A, Three-dimensional volume-rendering frontal image; B, axial image; C, lateral cephalograph; D, panoramic radiograph; E, superimposition (black color, initial; blue color, presurgical; red color, post-treatment).

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  Figure 13 Post-treatment photographs of a patient (Case 2) with an atypical type asymmetry.

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