• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.53-66
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• 2000

This study was performed to find out the effect of projection errors on cephalometric linear and angular measurements according to head rotation during taking lateral cephalometric radiographs. Seventeen skulls with permanent dentition and no gross asymmetry were obtained from the Department of Anatomy, Medical School, Chosun University. Total 527 x-ray films were taken with $1^{\circ}$ interval from the reference position($0^{\circ}$) to ${\pm}15^{\circ}$ around the vertical axis (Z axis) which is perpendicular to the midpoint of the line connecting the center of two ear rods in submento-vertex direction. Statistical analysis was performed by paired t-test if there were statistically significant differences between the mean of the reference position($0^{\circ}$) and that of each rotation angle. The following results were obtained. 1. The projection errors of angular measurements were smaller than those of linear measurements. 2. The projection errors of angular measurements including midline landmarks were smaller than those including bilateral landmarks. 3. The horizontal linear measurements were gradually decreased when the stroll was rotated toward the film, but slightly increased and then decreased when the skull was rotated toward the focal spot. However, the changes were smaller in focal direction. 4. The projection errors of horizontal linear measurements were larger than those of vertical linear measurements. 5. The projection errors of vertical linear measurements were increased with increased distance from the rotation axis to vertical measurements. It is concluded that the use of angular measurements rather than linear measurements is recommended to minimize the projection errors.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.412-420
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• 2001

In the growing children with normal occlusion and class III malocclusion who need the early treatment to be helped to diagnose and to set up treatment plan by calculating the mean values of the lateral cephalometric measurements, cephalometric measurements by McNamara alalysis were achieved and compared on both the 84 elementary school children with normal occlusion and 83 class III malocclusion children at the age of 7 to 9 in Kwangju city and the results were as follows: 1. On the boys group, between normal occlusion and class III malocclusion, Effective maxillary length, Maxillomandibular differential, Facial axis, Nasion perpendicualr to pogonion, Point A perp to Mx 1, and A-Pog line to Mn 1 showed significant differences(p<0.05). 2. On the girls group, between normal occlusion and class III malocclusion significant differences were shown in Effective Maxillary length, Maxillomandibular differential, Mandibular plan angle, Nasion perpendicualr to Point A, Point A perp to Mx 1, A-Pog line to Mn 1(p<0.01). 3. There were no significant differences between normal occlusion and class III malocclusion of boys group but significant differences between them of girls group in Effective mandibular length(P<0.01). On the boys and girls group, Effective maxilla length of class III malocclusion was shorter than that of normal occlusion. 4. There were no significant differences between normal occlusion and class III malocclusion both in boys and girls at Anterior lower facial height. 5. There were significant differences between boys and girls both in class III malocclusion and normal occlusion at Anterior lower facial height and Mandibular plane angle(p<0.01).

• The korean journal of orthodontics
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• v.25 no.4
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• pp.487-495
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• 1995

This study was undertaken to compare each maximum biting force and to investigate its relationship with the facial skeketal form, number and position of tooth contact between anterior openbite and normal occlusion adults, using the T-scan system and the lateral cephalogram. The subjects of this study consisted of a group of 25 individuals with normal occlusion and another group of 14 with anterior openbite. The obtained results of this study were as follows : 1. The maximum biting force of anterior openbite adults was less than that of normal occlusion adults. 2. In anterior openbite adults, there were negative correlations between the maximum, biting force and SN/MP, FMA, PP/MP mesurement of lateral cephalogram. 3. In anterior openbite adults, as the mesial angulation of lower first molar against the occlusal plane increased, the more the biting force decreased. 4. In both groups, the greater the number of tooth contact, the more the biting force increased. 5. In both groups, the center of effort for anteroposterior occlusal contact was located on the first molar region.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.459-474
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• 2005

Making a precise and ideal set-up model is an essential part in the indirect bonding procedure for lingual orthodontic treatment. To evaluate the accuracy of the making a set-up model, 22 adult patients who received lingual orthodontic treatment with 4 bicuspid extractions were selected, and 3 sets of dental models (before, set-up, and after treatment) were measured using the set-up model gauge, an instrument for measuring the inclination and angulation of the clinical crowns on the dental model. Two sets of lateral cephalograms (before and after) from each patient were also evaluated. The mean difference between the before treatment model and the set-up model was $-3.93{\pm}6.98^{\circ}$ for the inclination and $1.87{\pm}5.79^{\circ}$ for the angulation. And the mean difference between the set-up model and the after treatment model was $-4.31{\pm}5.91^{\circ}$ labiolingually and $-2.16{\pm}3.27^{\circ}$ mesiodistally, The after treatment model differed from the before treatment model about $-8.24{\pm}5.39^{\circ}$ in inclination. There were no significant difference between the measured gauge that measured from the dental model using the set-up model gauge and the calculated gauge angle measured from the lateral cephalogram using constructed points and lines. Using the set-up model gauge, it is possible to evaluate the study model 3-dimensionally in relation with the patient's lateral cephalogram and establish whether the doctor's prescription or overcorrection is built in the set-up model precisely.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.905-916
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• 1997

The purpose of this investigation were to evaluate facial vortical changes occurring in patients treated orthodontically with first premolar, second remolar and second molar extractions : to compare these changes with those occurring in patients treated orthodontically without extractions : and finally, to evaluate the effects of extractions in facial vortical changes. Cephalometric records of 50 male & female nonextraction patients and 88 male & female extraction patients were obtained from the department of orthodontics at Chosun University, College of Dentistry. The second molar fully erupted pPatients to have little variation according to growth were chosen as the sample for this investigation. For comparisons, the samples of 88 male & female extraction patients were subdivided into 42 first premolar extraction, 24 second premolar extraction, and 22 second molar extraction patients. Fourteen cephalometric measurements were selected to examine whether orthodontic extraction treatment led to vertical changes or not. The pretreatment and posttreatment lateral cephalographs were taken on the same radiographic unit. $SPSS/PC^+$ statistical program was used to compare and to analyze the changes between 'before & after' orthodontic treatment. The results of this study were as follows. 1. There were no statistical significances in any cephalometric measurements between 'before & after' orthodontic treatment regardless of orthodontic extractions for each group. 2. On average, the upper 6 to palatal Plane and the lower 6 to mandibular plane after orthodontic treatment were increased in all group. This means most of orthodontic mechanics are extrusive in nature. Especially, in orthodontic extraction. cases, it may be caused by orthodontic mechanics for space closure and alignments. 3. On average, in the second molar extraction group, the facial vertical dimension was increased after orthodontic treatment. It nay be induced as a result of moving the molars distally to gain enough space to correct the molar relationship and to simultaneously improve the deep bite. 4. There was no statistical significance between orthodontic extractions and facial vertical changes. This means that orthodontic extractions have no influence on facial vortical changes. 5. The cephalometric measurements with statistical significance in ficial vertical changes for each group were PP-MP, Op-MP, $\underline{1}$ to PP and $\overline{1}$ to MP.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.185-194
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• 2001

This study was designed to evaluate the effects of angulation changes of head posture on the enlargement ratios of a lateral headfilm depending on the vortical or horizontal rotation of the objects. A device was constructed to measure regional changes of enlargement ratios. The device was held within the cephalostat and cephalograms recorded at each measured degrees of the device tilting, vertically and horizontally. The enlargement ratios of the horizontal, vertical, and angular measurements on the films taken at each tilted angulations were obtained and compared with those on the films taken without rotation. In summary, the enlargement ratios of the horizontal linear measurements were decreased during horizontal rotations. The enlargement ratios of vortical measurements of the right side on the film were increased and those of the left side were decreased by the horizontal rotations. Enlargement ratios of horizontal measurements were affected further than those of vertical measurements by the same angular changes of the horizontal rotations. Therefore, a disruption of parallelism between the object's midsagittal plane and the film could result in distortion of the image while vertical rotation around the object's porionic axis would not significantly affect the enlargement ratios on the headfilm.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.289-299
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• 2009

Objective: The purpose of the present study was to evaluate the effectiveness of the use of Head Posture Aligner (HPA) during cone-beam computed tomography (CBCT) scan in generation of frontal cephalograms using 3D CBCT images. Methods: CBCT scans and frontal cephalograms were made in 30 adult individuals. While a couple of CBCT scan was made for one subject, one was made with conventional method, without use of HPA, the other was acquired with the use of HPA. After creation of virtual frontal cephalogram from each 3D CBCT image, it was traced and compared with the tracing of real frontal cephalogram. Results: In the comparison of the measurements, the virtual cephalograms with the use of HPA did not show statistically significant differences with the real cephalograms whereas the virtual cephalograms without the use of HPA presented significant differences with real cephalograms in many measurements. In the correlation analysis with the measurements of the real cephalograms, the virtual cephalograms with the use of HPA showed higher correlations in all measurements than the virtual cephalograms without the use of HPA. Conclusions: Measurements from CBCT-generated cephalograms become similar to those from real cephalograms with the use of HPA during CBCT scan. Thus, the use of HPA is suggested during the CBCT scan in order to construct accurate virtual frontal cephalograms using 3D CBCT images.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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• pp.73-81
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• 1991

The purpose of this study was to analyze the position of mandibular condyle on the submentovertex radiograph, thereafter to evaluate the usefulness of submentovertex radiograph in diagnosis of temporomandibular joint dysfunction, and to check the best method of tomographic techniques. Submentovertex radiographs which were taken in 75 temporomandibular joint dysfunction patients and 75 normal persons were used as the sample for this study. The obtained results were as follows: The submentovertex radiograph was a improper method in diagnosis of temporomandibular joint dysfunction and discrimination of affected side. The selective tomography was a better method than any other tomographic techniques in diagnosis of temporomandibular joint dysfunction.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.416-426
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• 2020

The purpose of this study was to calculate uncertainty of orthodontic measurement in skeletal class III malocclusion children using lateral cephalometry analysis software which obtained traceability in previous study. Using this data, standard reference of measurement value for skeletal class III malocclusion was obtained. Lateral cephalometric data was collected from 144 children who visited Pediatric Dentistry from 2017 to 2020 for orthodontic treatment. Orthodontic measurement was analyzed with software which obtained traceability. Type A evaluation of uncertainty and type B evaluation of uncertainty was calculated to obtain combined standard uncertainty and expanded uncertainty. Standard reference of skeletal class III children was compared to standard reference of skeletal class I children. Distribution range for skeletal class III malocclusion children aged 6 to 10 with 95% confidence interval was provided using calculated uncertainty of orthodontic measurement value.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.169-185
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• 1989

The purpose of this study was to establish Korean norms that will be valuable aids for diagnosis in orthognathic surgery patients. Lateral cephalometric measurements were established for adult Koreans (60 males, 62 females) with normal occlusion and acceptable profiles. The results were as follows: 1. Means, standard deviation and sexual differentiation were included within each measurement. 2. In skeletal measurements, FH to SN and SN to mandibular plane measurements in females were larger than those in males while all linear measurements in males were larger than those in males were larger than those in females. 3. Significant differences were observed between male and female groups on all of the items that showed vertical relationship in dental measurements. And the measurements of ADH, PDH and overbite in males were larger than those in females while the measurements of incisor exposure in females were larger than those in males. 4. In all measurements of soft tissue except NLA, that is, of FCA, UFH, ULL and LLL, males were larger than those in females.