• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.4
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• pp.337-345
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• 2011

Purpose: The purpose of this study was to define the relation of the degree of menton deviation and 3-D CT (computerized tomography) measurements of the glenoid fossa and the mandible, which are considered to have an influence on menton deviation. Methods: The CT images were obtained in 60 adults and these were transmitted to a computer and reconstructed using computer software. According to the degree of the menton deviation, which was measured on the posteroanterior cephalogram, the subjects were divided into the menton deviated group (30 adults) and the symmetry group (30 adults). A total of 11 measurements that might have an effect on menton deviation were determined and these were measured in the right and left sides using the function of 3-D measurement in the computer program. The 11 measurements consist of 6 measurements in the glenoid fossa (vertical position of the glenoid fossa and articular eminence, the sagittal position of the glenoid fossa and articular eminence, the depth of the glenoid fossa, and the anterior angle of the glenoid fossa), and 5 measurements in the mandible (ramus length, frontal ramal inclination, lateral ramal inclination, body length, body height). Results: The comparison of the differences between the menton deviated and symmetry groups and correlation analysis on the degree of menton deviation were carried out. The results of comparison of the right and the left difference between the menton deviated and symmetry groups showed that the vertical position and depth of the glenoid fossa were significantly increased in the menton deviated group. Conclusion: The results of the present study show that consideration of the shape and position of the glenoid fossa is necessary for making the diagnosis and administering proper treatment in facial asymmetry patients and especially growing patients.

• The korean journal of orthodontics
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• v.48 no.2
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• pp.73-80
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• 2018

Objective: This retrospective study compared the three-dimensional (3D) structure of mandibular condyles between adults with and without facial asymmetry, and whether it influences menton deviation. Methods: Sixty adult patients were classified into symmetry and asymmetry groups based on the menton deviation on postero-anterior radiographs. The right/left differences of 3D measurements were compared between the two groups, and measurements were compared separately on the right and left sides. The correlations between menton deviation and the right/left differences were analyzed. Results: The mediolateral dimension, neck length, condylar angles to the anteroposterior reference (PO) and midsagittal reference planes, and neck and head volumes showed significantly larger right/left differences in the asymmetry group compared to the symmetry group. Separate comparisons of the right and left sides between the two groups showed that the neck was significantly shorter and neck and head volumes were significantly smaller on the left side, which was deviated side in the asymmetry group. Pearson's correlation analysis showed significant positive correlations of menton deviation with right/left differences in neck length, condylar angle to the PO plane, and neck and head volumes in the asymmetry group. Conclusions: In individuals with facial asymmetry, menton deviation is associated with the right/left differences caused by a smaller condyle on the deviated side, particularly in neck length and neck and head volumes.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.153-163
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• 2015

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 $35^{\circ}$. 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.

• The korean journal of orthodontics
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• v.30 no.5 s.82
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• pp.535-542
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• 2000

The purpose of this study was to find the characteristics of the frontal natural head position(NHP) of patients with facial asymmetry, and to contribute to the diagnosis of facial asymmetry in the clinical examination of orthodontic patients. Twenty adult patients who had apparent facial asymmetry and no severe sagittal skeletal discrepancy were selected as the asymmetry group, and 21 young adults who had symmetric faces were selected as the symmetry group. Frontal cephalograms were obtained in the state of NHP using a pivot-mounted fluid level device. The degree of the menton deviation was defined as the angle between the line drawn through crista galli and anterior nasal spine and the line drawn through crista galli and menton. The following angles were measured and each of them was compared with the degree of the menton deviation one is the angle between the true vertical line and the supra-orbital line which is a tangent line to the extreme cranial point on the supra-orbital margin, and the other is the angle between the true vertical line and the cervical line drawn through the midpoint of atlas and the 4th cervical vertebra. Through the statistical analysis, following results were obtained. 1. The angle between the supra-orbital line and the true vertical line was much mote deviated from the right angle in the asymmetry group than in the symmetry group. 2. The angle between the cervical line and the true vertical line in the asymmetry group showed greater tendency than in the symmetry group, but the difference was not statistically significant. 3. In the asymmetry group, the degree of the menton deviation was positively correlated with the angle between the supraorbital line and the true vertical line. The above results suggest that racial asymmetry patients show the tendency to have the tilted NHP to compensate the deviation of menton position.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.300-309
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• 2009

Objective: The purpose of this study was to evaluate the correlation between menton deviation and dental compensation in facial asymmetry. Methods: Tooth axis and distance of first molar and canine to the reference plane were investigated by cone-beam computerized tomography. The subjects consisted of 50 patients with asymmetric mandibles (male 21, female 29, mean age 24.3 years). Control groups were also assessed (male 11, female 9, mean age 25.6 years). Nine measurements (5 linear measurements and 4 angular measurements) were measured in order to evaluate the correlation between menton deviation and the linear and angular difference of first molar and canine in the deviated and none-deviated sides using the defined MPR images. The differences between deviated and non-deviated side, according to menton deviation, were statistically analyzed using stepwise multiple regression analysis. Results: From the result, Menton deviation was negatively correlated with mandibular first molar's angular measurement (${\Delta\angle}LM6$-Mn plane (dev.-ndev.)) and positively with maxillary fist molar's angular measurement (${\Delta\angle}UM6$-FH plane (dev.-ndev.)) (p < 0.01). Two angular measurements (${\Delta\angle}LM6$-Mn plane (dev.-ndev.), ${\Delta\angle}UM6$-FH plane (dev.-ndev.)) explained the variability in menton deviation with a significant $r^2$ value of 0.589. Conclusions: This study suggests that the tooth axis of upper and lower first molars leans towards the deviated side of Menton when there is mandibular asymmetry with Menton deviation.

• The korean journal of orthodontics
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• v.46 no.2
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• pp.81-86
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• 2016

Objective: The aims of this study were to assess the direction and degree of lip-line cant in Korean adult orthodontic patients and to identify the effects of sex and age on changes in the cant severity. Methods: In this cross-sectional retrospective study, lip-line cant was measured in the frontal photographs of 585 Korean patients (92 men and 493 women) aged 18-48 years. The outcome variables (direction and degree of lip-line cant) were assessed in terms of predictor variables (sex, age, sagittal skeletal relationship, and menton deviation angle). Results: The direction of lip-line cant did not differ according to sex, age, or skeletal classification. Patients had $1.6^{\circ}$ of lip-line cant on average before orthodontic treatment. Middle-aged adults displayed a significant trend toward a lower degree of lip-line cant compared to younger adults (p < 0.01). Multiple linear regression analysis showed that the degree of lip-line cant was weakly negatively correlated with age (p < 0.001). Conclusions: While the direction of lip-line cant did not differ according to the parameters explored here, the degree of cant was correlated with age in adults, independent of menton deviation. Specifically, middle-aged adults tended to display significantly lower degrees of lip-line cant than did younger adults.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.1
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• pp.21-29
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• 2011

Introduction: To compare the change in frontal ramal inclination (FRI) in laterognathism after orthognathic surgery. Materials and Methods: Twenty four patients (10 men, 14 women; mean age, $22.8{\pm}5.2$ years) with minimal facial canting (${\leq}$ 2 mm) and apparent menton deviation ($5.9{\pm}2.4\;mm$) who had been operated on to correct facial asymmetry and skeletal CIII malocclusion, were selected. On a preoperative posteroanterior (PA) cephalogram, the FRI of the deviated side and non deviated side, L1 deviation amounts and menton deviation amounts were measured. The FRI differences between both sides were compared, and the correlations between the measured deviated elements and the FRI differences were analyzed. On a postoperative PA cephalogram, the shifting amount of L1, shifting amount of L7 and FRI of both sides were measured, and the correlations between the shifting elements and the change in FRI were analyzed. Results: On the preoperative PA cephalogram, the FRI of the non deviated side was significantly greater than those of the deviated side. The differences in FRI, with a menton deviation amount showed a significant correlation. On the postoperative PA cephalogram, the FRI differences between the deviated and non deviated side were decreased significantly and mandibular transverse movement toward central position was noted. The mean shifting amounts of L7 were associated with the amount of change in the deviated side of FRI. Conclusion: Transverse shifting of the mandible through orthognathic surgery decreases the FRI difference, which showed laterognathism, and improves the facial contour.

• The korean journal of orthodontics
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• v.48 no.6
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• pp.357-366
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• 2018

Objective: The purpose of this study was to analyze the transverse dental compensation in reference to the maxillary and mandibular basal bones using cone-beam computed tomography (CBCT) and evaluate the correlations between transverse dental compensation and skeletal asymmetry variables in patients with skeletal Class III malocclusion and facial asymmetry. Methods: Thirty patients with skeletal Class I (control group; 15 men, 15 women) and 30 patients with skeletal Class III with menton deviation (asymmetry group; 16 men, 14 women) were included. Skeletal and dental measurements were acquired from reconstructed CBCT images using OnDemand3D 1.0 software. All measurements were compared between groups and between the deviated and nondeviated sides of the asymmetry group. Correlation coefficients for the association between skeletal and dental measurements were calculated. Results: Differences in the ramus inclination (p < 0.001), maxillary canine and first molar inclinations (p < 0.001), and distances from the canine and first molar cusp tips to the midmaxillary or midmandibular planes (p < 0.01) between the right and left sides were significantly greater in the asymmetry group than in the control group. In the asymmetry group, the ramus inclination difference (p < 0.05) and mandibular canting (p < 0.05) were correlated with the amount of menton deviation. In addition, dental measurements were positively correlated with the amount of menton deviation (p < 0.05). Conclusions: Transverse dental compensation was correlated with the maxillary and mandibular asymmetry patterns. These results would be helpful in understanding the pattern of transverse dental compensation and planning surgical procedure for patients with skeletal Class III malocclusion and facial asymmetry.

• The korean journal of orthodontics
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• v.41 no.2
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• pp.87-97
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• 2011

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.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.6
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• pp.360-367
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• 2013

Purpose: The purpose of this study was to perform three-dimensional (3D) assessment of facial soft tissue in patients with skeletal Class III and mandibular asymmetry after orthognathic surgery. Methods: Samples consisted of 3D facial images obtained from five patients with A point-nasion-B point angle less than 2 degrees, and more than 5 mm of menton deviation. All patients had been treated at Gangneung-Wonju National University Dental Hospital from 2009 to 2012. They had undergone orthognathic surgery of Lefort I, and sagittal split osteotomy for correction of skeletal deformity, and orthodontic treatment. Facial scanning was performed before treatment (T1) and post-surgical orthodontic treatment (T2). Linear and angle variables of soft tissue landmarks, antero-posterior facial depth, and facial volume were measured. Results: No significant differences in width of the alar base, mouth width, and nasal canting were observed between T1 and T2. However, lip deviation, menton deviation, alar canting, lip canting, and menton deviation angle were significantly reduced at T2. Antero-posterior facial depth on the axial plane parallel to the left cheilion was significantly reduced on the deviated side and significantly increased on the non-deviated side at T2. Volume of the lower lateral and lower medial parts of the face was reduced on the deviated side, and volume of upper lateral and lower lateral parts on the non-deviated side was significantly increased at T2. Conclusion: After orthognathic surgery, facial asymmetry of soft tissue was improved following skeletal changes, especially the mandibular region. Although the length of the alar base and mouth width did not change, lip and soft tissue menton were displaced to the medial side after treatment. Facial depth also became symmetric after treatment. Facial volume showed a decrease on the lower part of the deviated side and that on lateral parts of the non-deviated side showed an increase after treatment.