Korean J Orthod.  2015 Jul;45(4):153-163. 10.4041/kjod.2015.45.4.153.

Cone-beam computed tomography based evaluation of rotational patterns of dentofacial structures in skeletal Class III deformity with mandibular asymmetry

• Ryu HS
• An KY
• Kang KH

• KMID: 2400573
• DOI: http://doi.org/10.4041/kjod.2015.45.4.153

Abstract

OBJECTIVE
The purpose of this study was to assess rotational patterns of dentofacial structures according to different vertical skeletal patterns by cone-beam computed tomography (CBCT) and analyze their influence on menton deviation in skeletal Class III deformity with mandibular asymmetry.
METHODS
The control group consisted of 30 young adults (15 men, 15 women) without any severe skeletal deformity. The asymmetry group included 55 adults (28 men, 27 women) with skeletal Class III deformity and at least 3-mm menton deviation from the midsagittal plane; it was divided into the hyperdivergent and hypodivergent subgroups using a mandibular plane angle cutoff of 35degrees. Fourteen rotational variables of the dental arches and mandible were measured and compared among the groups. Correlations between menton deviation and the other variables were evaluated.
RESULTS
The asymmetry group showed significantly larger measurements of roll and yaw in the mandible than the control group. The hypodivergent subgroup showed significant differences in maxillary posterior measurements of yaw (p < 0.01) and maxillary anterior shift (p < 0.05) compared with the hyperdivergent subgroup. All the mandibular measurements had significant correlations with menton deviation (p < 0.01). Most measurements of roll were positively correlated with one another (p < 0.01). Measurements of yaw and roll in the posterior regions were also positively correlated (p < 0.05).
CONCLUSIONS
Menton deviation in skeletal Class III deformity with mandibular asymmetry is influenced by rotation of mandibular posterior dentofacial structures. The rotational patterns vary slightly according to the vertical skeletal pattern.

Keyword

Cone-beam computed tomography; Facial asymmetry

MeSH Terms

Adult
Cone-Beam Computed Tomography*
Congenital Abnormalities*
Dental Arch
Facial Asymmetry
Humans
Male
Mandible
Young Adult

Figure

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  Figure 1 Landmarks used in this study. A, Facial skeleton. B, Maxillary dental arch. C, Mandibular dental arch. FZP, Or, and Go are bilateral landmarks. See Table 2 for definitions.

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  Figure 2 Reference planes used in this study. See Table 3 for definitions.

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  Figure 3 Positive upper canine roll relative to the direction of menton deviation.

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  Figure 4 Positive sign of lower anterior yaw relative to the direction of menton deviation.

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  Figure 5 Positive upper anterior shift relative to the direction of menton deviation.

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  Figure 6 Measurements of roll in this study. A, Maxillary dental arch. B, Mandibular dental arch. See Table 4 for definitions.

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  Figure 7 Measurements of yaw in this study. A, Maxillary dental arch. B, Mandibular dental arch. C, Mandible. LAY, Lower anterior yaw; LPY, Lower posterior yaw.

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  Figure 8 Measurements of shift in this study. See Table 4 for definitions.

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