• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제39권2호
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• pp.71-76
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• 2013

Objectives: In three-dimensional computed tomography (3D-CT), the cant is evaluated by measuring the distance between the reference plane (or line) and the tooth. The purpose of this study was to determine the horizontal skeletal reference plane that showed the greatest correlation with clinical evaluation. Materials and Methods: The subjects were 15 patients who closed their eyes during the CT image taking process. The menton points of all patients deviated by more than 3 mm. In the first evaluation, clinical cant was measured. The distance from the inner canthus to the ipsilateral canine tip and the distance from the eyelid to the ipsilateral first molar were obtained. The distance between the left and right sides was also measured. In the second evaluation, skeletal cant was measured. Six reference planes and one line were used for the evaluation of occlusal cant: 1) FH plane R: Or.R - Or.L - Po.R; 2) FH plane L: Or.R - Or.L - Po.L; 3) F. Ovale plane R: Rt.F.Ovale - Lt.F.Ovale - Or.R; 4) F. Ovale plane L: Rt.F.Ovale - Lt.F.Ovale - Or.L; 5) FZS plane R: Rt.FZS - Lt.FZS - Po.R; 6) FZS plane R: Rt.FZS - Lt.FZS - Po.L, and; 7) FZS line: Rt.FZS - Lt.FZS. Results: The clinical and skeletal cants were compared using linear regression analysis. The FH plane R, FH plane L, and FZS line showed the highest correlation (P<0.05). Conclusion: The FH plane R and FH plane L are the most appropriate horizontal reference plane in evaluation of occlusal cant on 3D-CT.

• 대한치과교정학회지
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• 제24권4호
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• pp.787-798
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• 1994

The purpose of this study was three-fold: i) to investigate the degree of asymmetry in Angle's Class III malocclusion patients and normal adults; ii) to determine the nature of difference existed between two groups; and iii) to investigate the correlationship between the degree of asymmetry and ANB and overbite in Angle's Class III malocclusion patients. The subjects consisted of 25 Angle's Class III malocclusion patients and 25 normal adults and the mean ages were 22.0 and 24.5 years, respectively. Their posteroanterior and lateral cephalograms were traced and analysed with three-dimensional approach. The results were as follows: 1. Asymmetry of Angle's Class III malocclusion group was significant in all regions except cranial base. Their horizontal asymmetry was seen in mandibular angle, maxillary and mandibular 1st molar, mandibular midline and menton. Vertical asymmetry was observed in maxillary 1st molar and mandibular shape and anteroposterior asymmetry in mandibular angle. 2. Nine variables indicating asymmetry were selected and each variable had similar discriminant score. 3. There was a little correlationship between An and asymmetric variable(MSR-B6) and its correlation coefficients was 0.3564. 4. There was no significant correlationship between overbite and asymmetric variables.

• 대한치과교정학회지
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• 제47권4호
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• pp.256-267
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• 2017

Objective: To evaluate transverse skeletal and dental changes, including those in the buccolingual dental axis, between patients with skeletal Class III malocclusion and facial asymmetry after bilateral intraoral vertical ramus osteotomy with and without presurgical orthodontic treatment. Methods: This retrospective study included 29 patients with skeletal Class III malocclusion and facial asymmetry including menton deviation > 4 mm from the midsagittal plane. To evaluate changes in transverse skeletal and dental variables (i.e., buccolingual inclination of the upper and lower canines and first molars), the data for 16 patients who underwent conventional orthognathic surgery (CS) were compared with those for 13 patients who underwent preorthodontic orthognathic surgery (POGS), using three-dimensional computed tomography at initial examination, 1 month before surgery, and at 7 days and 1 year after surgery. Results: The 1-year postsurgical examination revealed no significant changes in the postoperative transverse dental axis in the CS group. In the POGS group, the upper first molar inclined lingually on both sides (deviated side, $-1.8^{\circ}{\pm}2.8^{\circ}$, p = 0.044; nondeviated side, $-3.7^{\circ}{\pm}3.3^{\circ}$, p = 0.001) and the lower canine inclined lingually on the nondeviated side ($4.0^{\circ}{\pm}5.4^{\circ}$, p = 0.022) during postsurgical orthodontic treatment. There were no significant differences in the skeletal and dental variables between the two groups at 1 year after surgery. Conclusions: POGS may be a clinically acceptable alternative to CS as a treatment to achieve stable transverse axes of the dentition in both arches in patients with skeletal Class III malocclusion and facial asymmetry.

• 대한치과교정학회지
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• 제50권4호
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• pp.258-267
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• 2020

Objective: This study aimed to analyze the correlation of horizontal and sagittal planes used in two-dimensional diagnosis with lip canting by using three-dimensional (3D) analysis. Methods: Fifty-two patients (25 men, 27 women; average age: 24 years) undergoing treatment for dentofacial deformity were enrolled. Computed tomography images were acquired, and digital imaging and communication in medicine files were reconstructed into a 3D virtual model wherein horizontal and sagittal craniofacial planes were measured. Subsequently, the correlations of lip canting with these horizontal and sagittal planes were investigated. Results: The mandibular symmetry plane, the occlusal plane, Camper's plane, the mandibular plane, Broadbent's plane, and the nasal axis plane were correlated with the amount of lip canting (Pearson's correlation coefficients: 0.761, 0.648, 0.556, 0.526, 0.438, and 0.406, respectively). Planes associated with the lower part of the face showed the strongest correlations; the strength of the correlations decreased in the midfacial and cranial regions. None of the planes showed statistically significant differences between patients with clinical lip canting (> 3°) and those without prominent lip canting. Conclusions: The findings of this study suggest that lip canting is strongly correlated with the mandibular symmetry plane, which includes menton deviation. This finding may have clinical implications with regard to the treatment of patients requiring correction of lip canting. Further studies are necessary for evaluating changes in lip canting after orthognathic surgery.

• Imaging Science in Dentistry
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• 제44권1호
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• pp.15-20
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• 2014

Purpose: This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT). Materials and Methods: A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side. Results: The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero. Conclusion: The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

• Imaging Science in Dentistry
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• 제45권4호
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• pp.227-232
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• 2015

Purpose: The purpose of this study was to evaluate the influence of methods of establishing the midsagittal reference plane (MRP) on the locations of midfacial landmarks in the three-dimensional computed tomography (CT) analysis of facial asymmetry. Materials and Methods: A total of 24 patients (12 male and 12 female; mean age, 22.5 years; age range, 18.2-29.7 years) with facial asymmetry were included in this study. The MRP was established using two different methods on each patient's CT image. The x-coordinates of four midfacial landmarks (the menton, nasion, upper incisor, and lower incisor) were obtained by measuring the distance and direction of the landmarks from the MRP, and the two methods were compared statistically. The direction of deviation and the severity of asymmetry found using each method were also compared. Results: The x-coordinates of the four anatomic landmarks all showed a statistically significant difference between the two methods of establishing the MRP. For the nasion and lower incisor, six patients (25.0%) showed a change in the direction of deviation. The severity of asymmetry also changed in 16 patients (66.7%). Conclusion: The results of this study suggest that the locations of midfacial landmarks change significantly according to the method used to establish the MRP.

• 대한치과교정학회지
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• 제50권1호
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• pp.3-12
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• 2020

Objective: This study compared three prominent midsagittal planes (MSPs) to identify the MSP that best approximates the true symmetrical MSP. Methods: Forty-three patients (mean age, 23.0 ± 8.20 years) were grouped as follows: group 1 consisted of 10 patients with skeletal Class I and a menton (Me) deviation of < 2 mm; group 2, 11 patients with skeletal Class III and a Me deviation < 2 mm; group 3, nine patients with skeletal Class III and a Me deviation of 2 to less than 4 mm; and group 4, 13 patients with skeletal Class III and an Me deviation ≥ 4 mm. The candidate MSPs were established by three-dimensional (3D) cone beam computed tomography (CBCT) reorientation methods (RMs): (1) the MSP perpendicular to the Frankfort horizontal (FH) plane while passing through the crista galli and basion; (2) the MSP including the nasion, incisive foramen, and basion; (3) the MSP including the nasion, anterior nasal spine, and posterior nasal spine. The mean absolute distances (MADs) to the MSPs were calculated from the coordinates of 1,548 points on 129 CBCT images. The differences in the values of the 3D coordinates among RMs were compared. Results: The MADs of the three RMs showed significant differences (p < 0.05). Most of the differences in values of the coordinates were not significant among RMs. Conclusions: Although the differences in distance among the three MSPs were minor, the MSP perpendicular to the FH plane while passing through the crista galli and basion best approximated the true symmetrical MSP.

• 치과방사선
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• 제7권1호
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• pp.31-38
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• 1977

A study was performed to investigate the size of tongue area and intermaxillary space area, and compare the sexual differences between normal Korean children and adults by introducing planimetric and linear analysis of the lateral cephalograms. The cephalograms were composed of 41 child male aged 10.8, 40 child female aged 10.5, 38 adult male aged 21.3 and 40 adult female aged 20.8 respectively. In order to study and measure the intermaxillary space area, the followings were selected, as reference items: occlusal plane, anterior intermaxillary space height, posterior intermaxillary space height, length of intermaxillary space. Among those reference items anterior intermaxillary space height and posterior intermaxillary space height were perpendicular to the maxillary plane. An. index, (equation omitted) While the tongue area was plotted by outline of tongue shadow, above a line extending from the vallecula to the most anterior point on the hyoid body, and above a line from the most anterior point of the hyoid body to the menton. The obtained results were as follows: 1. In general the measurements of male were larger than those of female in intermaxillary space area in childhood and adulthood group. but intermaxillary space area of childhood group showed no significant sexual difference, and that of adulthood group showed significant sexual difference when evaluated statistically. 2. In both groups the measurements of male were larger than those of female in tongue area and there are also statistical significance of sexual differences in both age groups. 3. Considerable growh changes between the childhood and adulthood groups were revealed in intermaxillary space area and tongue area, and the tongue had tendency to become relatively smaller when compared with the intermaxillary space in both sex.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권2호
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• pp.151-159
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• 2005

The purpose of this study was to evaluate the nasal deviation in mandibular prognathism with mandibulo-facial asymmetry. There were 40 patients whose mandibular prognathism with/without facial asymmetry were treated with orthognathic surgery from March 2002 to October 2003. The Group A(n=20) had a mandibulo-facial asymmetry over 6mm menton deviation in cephalogram PA and the Group B(n=20) had a mandibular prognathism. The preoperative frontal photograph, cephalogram PA and three dimensionalcomputed tomography(divided in hard tissuse image and soft tissue image) of two group was evaluated NDA(nasal deviation angle) and MDA(mandibular deviation angle). The NDA was statistical difference between asymmetry Group A and symmetry Group B(p<0.01), and was deviated in affected side of asymmetry. The MDA were also statistical difference between Group A and Group B(p<0.01), however the measurements of MDA between the frontal photograph, 3D-CT and cephalogram PA were similar to each others. The low correlation of NDA between frontal photograph and cephalogram PA in Group A and B demonstrate that we couldn't assess nasal deviation in cephalogram PA. It could be concluded that patients with mandibulo-facial asymmetry have a nasal deviation and clinician must remember this fact when they assess and treat patients.

• 대한치과교정학회지
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• 제49권1호
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• pp.41-48
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• 2019

Objective: This in-vivo study aimed to compare landmark identification errors in anteroposterior (AP) and posteroanterior (PA) cephalograms generated from cone-beam computed tomography (CBCT) scan data in order to examine the feasibility of using AP cephalograms in clinical settings. Methods: AP and PA cephalograms were generated from CBCT scans obtained from 25 adults. Four experienced and four inexperienced examiners were selected depending on their experience levels in analyzing frontal cephalograms. They identified six cephalometric landmarks on AP and PA cephalograms. The errors incurred in positioning the cephalometric landmarks on the AP and PA cephalograms were calculated by using the straight-line distance and the horizontal and vertical components as parameters. Results: Comparison of the landmark identification errors in CBCT-generated frontal cephalograms revealed that landmark-dependent differences were greater than experienceor projection-dependent differences. Comparisons of landmark identification errors in the horizontal and vertical directions revealed larger errors in identification of the crista galli and anterior nasal spine in the vertical direction and the menton in the horizontal direction, in comparison with the other landmarks. Comparison of landmark identification errors between the AP and PA projections in CBCT-generated images revealed a slightly higher error rate in the AP projections, with no inter-examiner differences. Statistical testing of the differences in landmark identification errors between AP and PA cephalograms showed no statistically significant differences for all landmarks. Conclusions: The reproducibility of CBCT-generated AP cephalograms is comparable to that of PA cephalograms; therefore, AP cephalograms can be generated reliably from CBCT scan data in clinical settings.