• The korean journal of orthodontics
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• v.19 no.2
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• pp.165-175
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• 1989

In evaluation of some area within the craniofacial complex posteroanterior cephalogram together with lateral cephalogram is used for assessment of the exact existence and posture by grasping 3-dimensional concept. The usages of posteroanterior cephalogram in orthodontics are following; 1. The use during diagnosis and treatment planning 1) Assessment of the area and amount of facial asymmetry. 2) Assessment of therapeutic position for diagnosis and treatment 2. The Assessment of success in orthodontic mechanics If we use posteroanterior cephalogram together with lateral cephalogram adequately and simultaneously we can establish the exact diagnosis and appropriate treatment planning.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.293-304
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• 1990

The purpose of this study was to describe the morphologic differences between long-face adults and normal-face adults on the lateral and P-A cephalograms. Long-face and normal-face subifects were selected clinically, and then each of them was taken the lateral cephalogram. According to SN-MP angle and ATFH on the lateral cephalogram, long-face group and normal-face group were classified. 2 long-face adults and 18 normal-face adults were collected, and each of them was taken the P-A cephalogram. The results were as follows: 1. The morphologic differences between long-face adults and normal-face adults were closely related to mandibular morphology. 2. Long-face adults, compared with normal-face adults, demonstrated significant increase in ALFH, and significant decrease in ramus height. 3. Long-face adults, compared with normal-face adults, demonstrated significant increase in AUDH and, ALDH, especially in ALDH. 4. On the P-A cephalogram, no measures of transverse dimension demonstrated significant differences between two groups. 5. On the P-A cephalogram, facial height/facial width ratio was significantly larger than normal in the long-face adults, and in the normal-face adults, facial height/facial width ratio was approximately 90%. 6. In the correlation analysis of SN-MP angle and ATFH with all the other variables, the correlation coefficients of SN-MP angle and PTFH/ATFH that of ATFH and ALFH on the lateral cephalogram demonstrated the highest value, and on the P-A cephalogram, SN-MP angle and Cg-GA-Me (Lt.), ATFH and lower facial height demonstrated the highest value of correlation coefficients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.4
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• pp.239-244
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• 2003

The common errors in preoperative treatment plan for the orthognathic surgery can be occurred during cast impression, cast mounting procedure with face-bow transfer, surgical stent fabrication, and so on. One of the most common errors exists during mounting process of the model on the articulator. Accurate mounting of dental casts to articulator should be achieved by transferring the 3-dimensional spatial relationship of the maxillary arch to an articulator. A face-bow is used for transfer this relationship to articulator, usually by relating the face-bow to a plane of reference of maxillary cast. The purpose of this study is evaluation of the accuracy of face-bow transferring of maxillary model to the articulator. The maxillary casts of thirty patients for orthognathic surgery were mounted on articulator with an face-bow instrument. The relationship of occlusal plane angle to Frankfort horizontal plane relations were compared the cephalogram with the cast-mounted articulator. As a result of this study, the significant difference between the maxillary occlusal planes angle in the cephalogram and articulator were found. The results were followed, 1. The mean occlusal plane angle in cast-mounted articulator was $13.5^{\circ}\;(SD{\pm}5.4)$. 2. The mean occlusal plane angle in cephalogram was $10.4^{\circ}\;(SD{\pm}4.3)$. 3. The mean difference of occlusal plane angle between cast-mounted articulator and cephalogram was $3.3^{\circ}\;(SD{\pm}4.6)$. According to the result, we should suggest that the occlusal plane angle to Frankfort plane in cast-mounted articulator is more steeper than that of cephalogram. And then, maxillofacial surgeon should try to get a more predictable result by suggesting the proper correction method and mounting the cast accurately.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.11-36
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• 1989

Mandibular movements are guided mainly by three determinants, namely the two posterior controls (the Temporomandibular joints) and the anterior control (the incisal guidance). The aim of this study was to evaluate the incisal guide angle in effort to reconcile a patient's condylar guide angle and incisu guide angle, to develop criteria for incisal guidance in clinical practice. 48 subjects (male 33, female 15) with intact intercuspation, without past history and symptoms of stomatognathic system, were selected for this study. All of the subjects had not anterior prostheses. The sagittal condylar guide angles and incisal guide angles were measured and estimated statistically by cephalogram and articulator (Whip-Mix 8500A). The results of this study were as follows: 1. Average of condylar guide angle was 43.33 degree by cephalogram, and was 35.18 degree by articulator. 95% confidence interval was from 40.43 to 46.23 degrees in cephalogram and was from 32.98 to 37.38 degrees in articulator. 2. Average of incisal guide angle was 51.51 degree by cephalogram, and was 44.11 degree by articulator. 95% confidence interval was from 49.12 to 54.95 degrees in cephalogram and was from 40.67 to 47.56 douses in articulator. 3. Difference between condylar and incisal guide angle was 8.18 degree by cephalogram, and was 8.94 degree by articulator. 95% confidence interval was from 4.61 to 11.74 degrees in cephalogram and was from 4.90 to 12.98 degrees in articulator. 4. In case of the incisal guide angle steeper than condylar guide angle, subjects were 69% (33 of 48) in cephatogram and 75% (36 of 48) in articulator. 5. By the multiple regression equation, condylar guide angle was more influenced by the anterior teeth. 6. When the mandible protrudes from the intercuspal position to the edge to edge position the incisal linear movement was 4.18mm (S.D.:1.30mm) and the condylar linear movement was 4.38mm (S.D.:1.26mm).

• Journal of Yeungnam Medical Science
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• v.18 no.1
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• pp.123-137
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• 2001

Background: The purpose of this study is to evaluate the accuracy of measurements obtained from 3-dimensional computerized tomography and 3-dimensional cephalogram constructed by using the frontal and lateral cephalogram of six human dry skulls. Materials and Methods: After CT scans and each cephalograms were taken, 3-dimensional coordinates (X, Y, Z) of landmarks were obtained using computer programs. In this study, the accuracy of both methods were determined by means of 14 linear measurements compare with caliper measurements. Results: The standard deviation of landmarks of 3-dimensional CT and 3-dimensional cephalogram were 0.23 mm, and 0.30 mm in X axis, 0.27 mm and 0.25 mm in Y axis, and 0.27 mm and 0.31 mm in Z axis. In both methods, the standard deviation were less than 0.5 mm in all landmarks, and the most of landmarks showed less than 1 mm in range. Concerning the accuracy, the mean difference between 3-dimensional CT and manual measurements was 0.33 mm, and 1.13 mm between 3-dimensional cephalogram and manual measurements. The distance between RGo and LGo showed the largest difference (2.03 mm). There were highly significant, and large correlation with manual measurements in both methods (p<0.01). Conclusion: It is concluded that closeness of repeated measures to each skulls reveal the precision of both methods. Computerized tomography and cephalogram for 3-dimensional measurement of maxillofacial structure are equivalent in quality to caliper measurements.

• The korean journal of orthodontics
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• v.23 no.3 s.42
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• pp.359-374
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• 1993

At present, many orthodontists regard the root parallelism of the posterior teeth important not only in diagnosis and treatment planning but also for predicting posttreatment stability. To evaluate it, they usually refer to the orthopantomogram. At this study, 97 samples were collected from students of Yonsei University, who have well-proportioned face, Angle's class I canine & molar relationships and no crown axis deviation of the posterior teeth including canines. Reliability of the root parallelism observed from orthopantomogram was evaluated by comparison with $45^{\circ}$ oblique cephalogram. The results were as follows : 1. In comparing the differences between anglular measurements in $45^{\circ}$ oblique cephalogram & orthopantomogram with $5^{\circ}$, those to mandibular plane were significantly less than to occlusal plane in number of items which showed less differences than $5^{\circ}$. 2. Compared the root parallelisms in the orthopantomogram with those in $45^{\circ}$ oblique cephalogram with $1\%$ significance level, parallelism between upper canine & 1st premolar, lower canine & 1st premolar, lower 1st premolar & 2nd premolar, and lower right 2nd molar & 3rd molar showed statistically significant differences. 3. When the significance between the differences of the root parallelism between above two kinds of film and $5^{\circ}$ was verified by two sided paired t-test, more or less large difference was shown between lower right 2nd molar & 3rd molar, a little larger than $5^{\circ}$ between lower canine & 1st premolar, smaller at the rest of them. 4. In $45^{\circ}$ oblique cephalogram, lower canine & 1st premolar showed convergent root arrangements each other, while in orthopantomogram they were divergent each other. All the others except them showed convergency on the upper, divergency on the lower in both films.

• 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.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.2
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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.

• The Journal of the Korean dental association
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• v.36 no.2 s.345
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• pp.135-143
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• 1998

Cephalogram is one of the most important tool in researching growth and development of craniofacial area, orthodontic diagnosis and treatment planning. But its inherent distortion of actual length and angles during projecting three dimensional object to two dimensional plane might cause errors in quantitative analysis of shape and size. three dimensional high quality images can be obtained using computerized tomogram and have reported in literatures. Considering its expenses and amount of exposure to radiation, limitations still remain to be solved in its application to routine practice. construction of three dimensional image using principle of orientator can be obtained by biplanar stereoradiography. Theoretically two images, lateral and P-A can be used to construct three dimensional image provided that those are taken at same time by two different focal spots. As two images(lateral and P-A) obtained by conventional cephalogram have different head posture, those need compensation to construct three dimensional images. This study introduced principle of computerized head posture compensation and showed that conventional cephalogram could be used to construct three dimensional image and could be applied to routine orthodontic practice.

• Journal of the korean academy of Pediatric Dentistry
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• v.3 no.1
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• pp.48-51
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• 1976

Surveying the developmental degree of the crowns of mandibular first bicuspid in 566 korean children (264 males and 302 females) from 3 to 7 years of age by oblique cephalogram, the author got to the following results. 1. The developmental degree of the tooth crown of mandibular first bicuspid was earlier in female than in male. 2. The period of complete development of the crown of mandibular first bicuspid was 7 year 1 month in male and 6 year 3 month in female. 3. There was no significant difference in the period of complete development of the tooth crown compared with that of Japanese and American children.