• 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 Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.129-135
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• 1994

This study was performed to evaluate the accuracy of orthopantomogram by measuring the actual and radiographic tooth length and by analyzing the vertical magnification rate. For this study, total 90 teeth of the maxilla and mandible teeth and a dry skull were used. This experiment was attached with metal balls of 1±0.02㎜ at the root and the crown cusp tips of central, 2nd premolar, 1st molar of the maxilla and mandible and the teeth were embedded in dry skull, and then orthopantomogram was taken. The obtained results were as follows: 1. The average of tooth length in orthopantomogram was longer than that of actual tooth length. 2. The average of vertical magnification rate in the orthopantomogram to actual tooth length was 17-26%. 3. Vertical magnification rate of the maxilla teeth was 18-26% and that of mandibular teeth was 17-23%, and the magnification of maxillary teeth was larger than that of mandible teeth(P<0.0l). 4. Vertical magnification rate of posterior area was 22-26% and that of anterior area was 17-18%, and the magnification of anterior area was less than that of posterior area(P<0.01).

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.523-538
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• 1997

In order to investigate TMD prevalence in malocclusion patients and to study its relationship with occlusal factors, 205 malocclusion patients (M67, F138, 6Y1M-46Y8M) were examined. The following examinations were carried out, Questionnaire personal history, TMD symptoms, and the associated factors Clinical examination : TMJ sound and maximum mouth opening Orthopantomogram : condyle abnormalities, length of Co'-Inc' and Co'-Go', ratio Co'- Inc'/ Co'-Go', and depth of antegonial notch Transcranial view limitation of anterior movement of condyle Model Angle classification, overjet, overbite, midline discrepancy, missing of posterior teeth, posterior crossbite, attrition of palatal cusp of maxillary molars, crowding/spacing The results could be summarized as follows, 1. The prevalence of TMD showed that Helkimo Anamestic Inder(Ai) 0 was $46.8\%$, Ai I was $22.0\%$, Ai II was $31.2\%$ and subjective symptoms increased with aging (p<0.001) and were frequent in females (p<0.05). 2. Flattening ($4.4\%$) was the most frequent condyle abnormality on Orthopantomogram, and $8.3\%$ of subjects showed some abnormalities on Orthopantomogram. 3. The cases with neck and shoulder pain (p<0.001), clenching, lip biting (p<0.01), and headache (p<0.05) showed higher scores of Ai. 4. Angle class II showed high frequency of condylar abnormalities on Orthopantomogram, and subjects whose palatal cusp of maxillary molars had been attrided had the tendency to show high hi scores (p<0.05). The other occlusal factors had nothing to do with the symptoms of TMD. 5. In the cases that 1)the value of Co'-Inc', Co'-Go' or Co'-Inc'/Co'-Go' were low or 2)the differences of Co'-Go' or Co'-Inc'/Co'-Go' between the right and the left were large, condylar abnormalities were frequently obserbed on Orthopantomogram.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.10 no.1
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• pp.63-68
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• 1980

The purpose of this article is to re-examine the roentgenographic appearance of alveolar osseous in an effort to determine the value of the orthopantomogram in the diagnosis of periodontal disease. A total of 158 osseous lesions from 13 human dry skulls were studied. 14 Ultra-speed periapical films, 2 bitewing films and Kodak panoramic film are used to obtain radiographs of all defects. The bisecting technic was used, with a target-film distance of. 8 inches and exposure factors of 70 kVp, 10MA and 0.4 sec. at anterior teeth, 0.6 see at posterior teeth in exposure time. For orthopantomogram, Panoura Eight-C was used with a exposure factors of 90kVp, 10MA. and 15sec. exposure time. All films were developed in a light. tight darkroom at 68°F for 4½ minutes. Comparison of orthopantomogram and intraoral films on the view-box was carefully studied in relation to the types of osseous defect visually evident; Proximal intraosseous defects, Interproximal craters, Interproximal hemisepta, Furcal defects on multirooted teeth, and Facial or Lingual one-walled defects. The results obtained were as follows; 1. Proximal osseous defects throughout the dental arches and furcal defects on facial and lingual surfaces of multirooted teeth can be identified with a high degree of accuracy from their orthopantomographic appearances. 2. Lesions on facial or lingual surface of the alveolar arches are rather difficult to locate or recognize on the dental radiographs. 3. In determining whether the proximal and furcal lesions are located facially or lingually, Orthopantomogram is superior to the conventional film Orthopantomogram obtained with standardization of head in proper position revealed the complete visualization of alveolar bone without showing occlusal surface of molars and proximal superimposition of teeth. Thus, on the standardized orthopantomograms, The roentgenographic characteristics of each defect were determined.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.25-30
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• 1986

The author studied the magnification ratio of teeth length in orthopantomogram through intraoral film taken by standardized paral1eing technique. In this study, intraoral radiograph and orthopantomogram were taken in 2 cases of dry skull and 36 adults (504 teeth). 1. The obtained results were as follows: In case of dry skull, the magnification ratio of standard films was 4.6% to 5.9% and that of Orthopantomograph 5 was 15.1% to 33.1%. The magnification ratio of to the standard film was 9.2% to 26.5% 2. In case of adults, the magnification ratio of Orthopantomograph 5 to the standard films was 9.5% to 24.6%. 3. There were no significant difference in magnification between left and right. 4. Anterior teeth had lesser magnification than posterior teeth. 5. It was considered that teeth length showed in Orthopontomograph 5 was magnified 15.4% to 31.3% than actual teeth length.

• The korean journal of orthodontics
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• v.11 no.2
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• pp.71-75
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• 1981

The author has studied on the gonical angles in cephalometric roentgenograph and orthopantomograph. Lateral cephalometric roentgenograms and orthopantomograms were taken from 62 patients who were consisted of 32 boys and 30 girls with dentoalveolar Class I malocclusion. Genial angles were measured on cephalograms and orthopantomograms respectively, and calculated the mean values and standard deviations and 't' test was performed on the relationship between the cephologram and orthopantomogram. Results were as followings; 1. Mean value of genial angles was $126.47^{\circ}\;{\pm}\;5.62$ in cephalgram. In orthopantomograms the gonial angle was $125.23^{\circ}\;{\pm}\;6.68$ in left side and $126.47^{\circ}\;{\pm}\;6.85$ in the right side. 2. Result of 't' test showed no significant differences on the level of 1 percent.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.31-39
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• 1986

This study was performed to compare the difference of intraoral bisecting and panoramic techniques in evaluating the relationship of antral floor and maxillary roots. The vertical distances from maxillary root apices to antral floor were measured on both orthopantomograms and bisecting projections obtained from fifty subjects. The results were as follows, 1. Tooth lengths measured on orthopantomogram were larger than on bisecting projection and the magnification ratios were 1.08-1.17. 2. The dimensions from maxillary root apices to antral floor measured on orthopantomogram were larger than on bisecting projection. 3. The above results held true regardless of age and sex.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.13 no.1
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• pp.107-115
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• 1983

This study was performed in order to analyse the morphology of maxillary sinus on orthopantomogram. The author anlaysed the anterior-posterior width of mesial wall, the extension of anterior margin in maxillary sinus and the interrelation between the root apex of maxillary 1st molar and sinus floor. The films consisted of 514 orthopantomograms divided into three groups ranging the 3rd decade, 4th and 5th decade and 6th decade. The obtained results were as follows: 1. The mean dimensions of the anterior - posterior width of mesial wall were 43.81±4.55㎜ for male and 43.80±4.49㎜for female in the right of maxillary sinus, 43.75±74㎜ for male and 43.37±3.92㎜ for female. 2. With age, the dimensional change of the anterior - posterior width of mesial wall in maxillary sinus was not observed. 3. The extension order of anterior margin of the maxillary sinus was distal to canine side, 1st premolar mesial side, canine mesial side, and 1st premolar distal side. 4. In the distance between the root apex of upper 1st molar and the maxillary sinus floor, the degree of closeness was more increased in the older-aged group than in the younger-aged group.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.151-159
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• 1989

The author has studied radiographic bony cnages of mandibular condyle head in temporomandibular disorder patients using Oblique lateral transcranial projection, Orthopantomography, and Tomography. The bony change types and the frequencies of occurrence and the incidences of bony changes in three different radiographic techniques were examined. The coincidences of bony change types between the Oblique lateral transcranial projection and the lateral part of Tomogram, the Orthopantomogram and the medial part of Tomogram were also examined. The results were as follows: 1. The mean age of patients was 31.7 years and under 40 years were 24 patients, women werw 27 patients, men were 4patients. 2. The observable case of bony changes in all three radiographic techniques were 19 cases (50%) of 38 cases and the observable cases of bony changes in only Tomography were 5 cases(13.2%) 3. The most frequent radiographic bony change type was osteophyte and next orders were flattening, erosion, concavity. 4. The positional incidences of bony change in Tomogram were 31 cases in lateral part and 27 cases in central part. 5. The coincidence of bony change types between the Oblique lateral transcranial projection and the lateral part of Tomogram was 80%, and the coincidence between the Orthopantomogram and the medial part or Tomogram was 76.0%.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.307-316
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• 1991

The purpose of this study is to improve the availabilities of radiographic technics as diagnostic method related to mandibular canal in dental clinic. For this study 12 dry mandibles were used and 12 orthopantomograms were taken for measuring the gonial angle and the angle of mandibular canal to inferior border of mandible. 12 sites located between the 1st premolar to the 3rd molar region of 3dry mandibles were selected randomly, for measuring the vertical image magnification rates on three films; intraoral film, orthopantomogram, and computed tomogram, respectively and the thickness of cortical bone, and for observing bucco-lingually and supero-inferiorly location of the mandibular canal. The acquired results were as follows: 1. The means of the gonial angle and the angle of mandibular canal to inferior border of mandible were 123.9° and 143.5° And the two angles of dry mandible in alveolar crest stage were greater than in alveolar socket stage. 2. The vertical image length on intraoral film by paralleling technic was magnified by 3.07% on the average, the length on orthopantomogram by 18.49%, and the length on computed tomogram by 0.27%. 3. Observation of the bucco-lingually positional relationship of the mandibular canal was impossible by occlusal projection with the cross section technic and intraoral standard projection with the Clack's rule, however, possible by computed tomogram. 4. The thickness of the cortical bone of mandible was thickest in inferior border, and thicker by 6.59% at buccal side than at lingual side.