• Imaging Science in Dentistry
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• v.41 no.2
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• pp.79-84
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• 2011

Purpose : The aim of the present study was to investigate the disagreement of cephalometric analysis depending on the reference determination of midsagittal plane on three-dimensional computed tomography. Materials and Methods : A total of 102 young women with class III dentofacial deformity were evaluated using three-dimensional computed tomography. The cranial and facial midsagittal planes were defined and the amounts of jaw deviation were calculated. The amounts of jaw deviation were compared with paired t-test (2-tailed) and Bland-Altman plot was drawn. Results : The landmark tracing were reproducible ($r{\ge}.978$). The jaws relative to the cranial midsagittal plane were 10-17 times more significantly deviated than to the facial midsagittal plane (P<.001). Bland-Altman plot demonstrated that the differences between the amounts of jaw deviation from two midsagittal planes were not normally distributed versus the average of the amounts of jaw deviation from two midsagittal planes. Conclusion : The cephalometric analyses of facial asymmetry were significantly inconsistent depending on the reference determination of midsagittal plane. The reference for midsagittal plane should be carefully determined in three-dimensional cephalometric analysis of facial asymmetry of patients with class III dentofacial deformity.

• Imaging Science in Dentistry
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• v.44 no.3
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• pp.207-212
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• 2014

Purpose: This study aimed to investigate the deviation of landmarks from horizontal or midsagittal reference planes according to the methods of establishing reference planes. Materials and Methods: Computed tomography (CT) scans of 18 patients who received orthodontic and orthognathic surgical treatment were reviewed. Each CT scan was reconstructed by three methods for establishing three orthogonal reference planes (namely, the horizontal, midsagittal, and coronal reference planes). The horizontal (bilateral porions and bilateral orbitales) and midsagittal (crista galli, nasion, prechiasmatic point, opisthion, and anterior nasal spine) landmarks were identified on each CT scan. Vertical deviation of the horizontal landmarks and horizontal deviation of the midsagittal landmarks were measured. Results: The porion and orbitale, which were not involved in establishing the horizontal reference plane, were found to deviate vertically from the horizontal reference plane in the three methods. The midsagittal landmarks, which were not used for the midsagittal reference plane, deviated horizontally from the midsagittal reference plane in the three methods. Conclusion: In a three-dimensional facial analysis, the vertical and horizontal deviations of the landmarks from the horizontal and midsagittal reference planes could vary depending on the methods of establishing reference planes.

• The korean journal of orthodontics
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• v.40 no.1
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• pp.6-15
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• 2010

Objective: The aim of this study is to find the most helpful midsagittal reference plane for diagnosis in PA cephalometry compared with 3D CT. Methods: The subjects consisted of 25 adults who showed no facial asymmetry by gross inspection. 3D CT and posteroanterior cephalogram of the subjects were taken. To find the most helpful midsagittal reference plane in PA cephalometry, we considered five kinds of midsagittal planes from which the distances to five landmarks were measured and compared the result with that of 3D CT. The midsagittal plane for 3D CT was determined by the landmarks Nasion, Sella and Basion. Results: PA measurements using the midsagittal reference plane on a perpendicular plane lying through the midpoint of the right and left latero-orbitales was closest to those of 3D CT. Conclusions: It was considered that latero-orbitale perpendicular could be used as the helpful midsagittal reference plane to assess facial asymmetry in PA cephalometry.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.1
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• pp.109-116
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• 1992

To determine the horizontal inclination of the condylar long axis without taking the submentovertex radiograph, the author studied the interrelation between the angle formed by the midsagittal plane and the mandibular angle and the horizontal inclination of the condylar long axis. In 56 subjects, the author measured the angle formed by the midsagittal plane and both mandibular angle using the modified Twirl Bow and the horizontal inclination of the both condylar long axis from submentovertex radiographs. The result were as follows: The mean value of the angle formed by the midsagittal plane and the mandibular angle was l8.50±1.48° in right side and 19.30±1.55° in left side. The mean value of the horizontal inclination of the condylar long axis was 19.25±7.56° in right side and 20.27±7.050 in left side. The interrelation of the two angles was represented as follows: y = 20.31-0.0094× (r = -0.482, p<0.01) in right side and y = 20.64-0.066×(r =-0.301, p<0.05) in left side (y; the horizontal inclination of the condylar long axis, x; the angle formed by the midsagittal plane and the mandibular angle).

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.475-484
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• 2005

This study was performed to investigate the reproducibility of the horizontal and midsagittal planes, and to suggest a stable coordinate system for three-dimensional (3D) cephalometric analysis. Eighteen CT scans were taken and the coordinate system was established using 7 reference points marked by a volume model, with no more than 4 points on the same plane. The 3D landmarks were selected on V works (Cybermed Inc., Seoul, Korea), then exported to V surgery (Cybermed Inc., Seoul, Korea) to calculate the coordinate values. All the landmarks were taken twice with a lapse of 2 weeks. The horizontal and midsagittal planes were constructed and its reproducibility was evaluated. There was no significant difference in the reproducibility of the horizontal reference planes, But, FH planes were more reproducible than other horizontal planes. FH planes showed no difference between the planes constructed with 3 out of 4 points. The angle of intersection made by 2 FH planes, composed of both Po and one Or showed less than $1^{\circ}$ difference. This was identical when 2 FH planes were composed of both Or and one Po. But, the latter cases showed a significantly smaller error. The reproducibility of the midsagittal plane was reliable with an error range of 0.61 to $1.93^{\circ}$ except for 5 establishments (FMS-Nc, Na-Rh, Na-ANS, Rh-ANS, and FR-PNS). The 3D coordinate system may be constructed with 3 planes; the horizontal plane constructed by both Po and right Or; the midsagittal plane perpendicular to the horizontal plane, including the midpoint of the Foramen Spinosum and Nc; and the coronal plane perpendicular to the horizontal and midsagittal planes, including point clinoidale, or sella, or PNS.

• Journal of the Korean Magnetic Resonance Society
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• v.13 no.2
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• pp.84-95
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• 2009

The purpose of this study was to evaluate the usefulness of the measurement of corpus callosum (CC) size in the Alzheimer patient by using magnetic resonance (MR) midsagittal image. We performed MR scanning in 20 normal high age group, and in 20 mild cognitive impairment (MCI) group, and in 20 Alzheimer disease (AD) group. The following parameters were employed in AD group: TRITE/FA 6650ms/66ms/$90^{\circ}$, NEX 2, Thickness/Gap 2/0, FOV 220mm. The magnetic field strength was used at 3.0 Tesla. We selected midsagittal image of the brain by using view forum program, measured CC size, which were anteroposterior length, diameter of genu, body, narrowing portion, and splenium. The present study demonstrates that CC size of Alzheimer disease can be useful for clinical assessment concerning the diameter of genu, body, and splenium.

• The korean journal of orthodontics
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• v.37 no.3 s.122
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• pp.182-191
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• 2007

Objective: The purpose of this study was to evaluate the validity of midsagittal reference (MSR) planes constructed in maxillofacial 3D images. Methods: Maxillofacial computed tomography (CT) images were obtained in 36 normal occlusion individuals who did not have apparent facial asymmetry, and 3D images were reconstructed using a computer software. Six MSR planes (Cg-ANS-Ba, Cg-ANS-Op, Cg-PNS-Ba, Cg-PNS-OP, FH${\perp}$(Cg, Ba), FH${\perp}$(Cg, Op)) were constructed using the landmarks located in the midsagittal area of the maxillofacial structure, such as Cg, ANS, PNS, Ba and Op, and FH plane constructed with Po and Or. The six pairs of landmarks (Z, Fr, Fs, Zy, Mx, Ms), which represent right and left symmetry in the maxillofacial structure, were selected. Statistically significant differences of the right and the left measurements were examined through t-test, and the difference of the right and the left measurement was compared among the six MSR planes. Results: The distances from the right and the left landmarks in each pair to each MSR plane did not show a statistically significant difference. The reproducibility of the landmark identification was excellent. Conclusion: All the six planes constructed in this study can be used as a MSR plane in maxillofacial 3D analysis, particularly, the planes including Cg and ANS.

• The Journal of the Korean dental association
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• v.13 no.5
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• pp.457-461
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• 1975

The author observed the relationships beween the dental midline and the midsagittal plane by taking 242 cases P-A cephalo-graphy grouped by male and female 2-6 years age group, 7-15 years age group, and adult age group. The following results were obtained by the observation. 1. Generally, the median line almost coincided with dental midline ineach age group. 1. It showed som degree of deviation in each age group. 2. It showed some degree of deviation in each age group. 3. The some degree of deviation shifted in accordance with each age group. 4. In adult age group, the dental milline more coincided with median line in male than in female.

• The korean journal of orthodontics
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• v.53 no.4
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• pp.219-231
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• 2023

Objective: This study aimed to clarify differences in the positions of cone-beam computed tomography (CBCT) landmarks according to different midsagittal planes (MSPs) in patients with skeletal Class III facial asymmetry. Methods: Pre-treatment CBCT data from 60 patients with skeletal Class III were used. The patients were classified into symmetric (menton deviations of < 2 mm) or asymmetric (menton deviations of > 4 mm) groups. Six MSPs were established based on previous studies, and three-dimensional analyses were performed for the planes in both the groups. The measurement outcomes were compared statistically. Results: A statistically significant interaction (p < 0.01) was observed between MSPs and facial asymmetry. No significant differences were observed among MSPs in the symmetric group. However, significant differences in linear measurements were identified among MSPs in the asymmetric group. Specifically, the upper facial MSP revealed both maxillary and mandibular transverse asymmetries. On the other hand, anterior nasal spine (ANS)-associated MSP could not identify maxillary asymmetry. Furthermore, the menton deviation was approximately 3 mm lower when estimated using the ANS-associated MSP than that using upper facial MSP. Conclusions: The choice of MSP can significantly affect treatment outcomes while diagnosing patients with asymmetry. Therefore, care should be taken when selecting MSP in clinical practice.

• The korean journal of orthodontics
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• v.45 no.6
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• pp.282-288
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• 2015

Objective: This study investigated whether it is possible to use a two-dimensional (2D) standard in three-dimensional (3D) analysis, by comparing the angles and lengths measured from a midsagittal projection in 3D cone-beam computed tomography (CBCT) with those measured by 2D lateral cephalometric radiography (LCR). Methods: Fifty patients who underwent both LCR and CBCT were selected as subjects. CBCT was reoriented in 3 different methods and the measuring-points were projected onto the midsagittal plane. Twelve angle values and 8 length values were measured on both LCR and CBCT and compared. Results: Repeated measures analysis of the variance revealed statistically significant differences in 7 angular and 5 linear measurements among LCR and 3 types of CBCT (p < 0.05). Of these 12 measurements, multiple comparisons showed that 6 measurements (ANB, AB to FH, IMPA, FMA, Co-Gn, Go-Me) were not significantly different in pairwise comparisons. LCR was significantly different from 3 types of CBCT in 3 angular (SN to FH, interincisal angle, FMIA) and 2 linear (S-Go, Co-ANS) measurements. The CBCT method was similar for all measurements, except for 1 linear measurement, i.e., S-N. However, the disparity between the mean values for all parameters was within the range of clinical measurement error. Conclusions: 3D-CBCT analysis, using midsagittal projection, is a useful method in which the 2D-LCR normative values can be used. Although the measurements changed with reorientation, these changes were not clinically significant.