• The Journal of the Korean dental association
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• v.35 no.11 s.342
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• pp.848-851
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• 1997

• Proceedings of the Korean Society of Radiological Science
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• 1996.06a
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• pp.28.3-29
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• 1996

• Journal of Digital Convergence
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• v.16 no.12
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• pp.441-447
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• 2018

This study aims to develop digital techniques that enable repeated practice of dental radiography using augmented reality technology. A three-dimensional object was fabricated by superimposing a photograph of an adult model and a computed tomography image of a manikin phantom. The system was structured using 106 radiographs such that one of these saved radiographs is opened when the user attempts to take a radiograph on a mobile device. This system enabled users to repeatedly practice at the pre-clinical stage without exposure to radiation. We attempt to contribute to enhancing dental hygienists' competency in dental radiography using these techniques. However, a system that enables the user to actually take a radiograph based on face recognition would be more useful in terms of practice, so additional studies are needed on the topic.

• Journal of Oral Medicine and Pain
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• v.33 no.2
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• pp.195-204
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• 2008

Osteoarthritis is caused by joint degeneration, a process that includes progressive loss of articular cartilage accompanied by attempted repair of articular cartilage, remodeling and sclerosis of subchondral bone, and osteophyte formation. The most common causative factor that either causes or contributes to osteoarthritis is overloading of the articular structures of the joint. The diagnosis of temporomandibular joint(TMJ) osteoarthritis is based on the patient's history and clinical findings such as limited mandibular opening, crepitation and tenderness to palpation on TMJ. The diagnosis is usually confirmed by TMJ radiographs, which will reveal evidence of structural changes in the subarticular bone of the condyle or fossa. Plain radiography techniques such as panoramic, transcranial, transpharyngeal views can be used in most dental offices for evaluation of the TMJs. However, plain radiographs are often limited due to overlapping and distortion of anatomical structures. The aim of this study was to compare the clinical examination and panoramic view with computed tomography for diagnosis of temporomandibular degenerative joint disease, and to compare the findings of condylar bony changes through panoramic radiography with that of computed tomography, hence, to confirm the limitations of clinical and panoramic radiography, and the validity of the computed tomography for diagnosis of temporomandibular degenerative joint disease. The pathophysiology of the TMJ osteoarthritis remains poorly understood, and current treatments are based more on speculation than science, and symptomatic treatments often fail to provide satisfactory pain relief. For diagnosis of TMJ osteoarthritis, clinical examination and radiographic examination for confirmation of the bony changes are essential, and computed tomography are clearly superior to plain radiographs for their limitations.

• Journal of Oral Medicine and Pain
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• v.38 no.3
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• pp.267-274
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• 2013

This study was performed to investigate the skeletal factors related to open lock of the temporomandibular joint(TMJ). We compared the skeletal measurements on the cephalogram and transcranial radiograph among 3 groups, open lock group consisting of consecutively filed 50 patients with at least one open lock episode within recent 1 year, temporomandibular disorder(TMD) group of 50 TMD patients without open lock diagnosed by Research Diagnostic Criteria for TMD (RDC/TMD) Axis I, and normal group of 50 patients without TMD or open lock. The patients of TMD and normal group were randomly selected in an age-and-gender-matched way with ones of open lock group. Open lock group showed smaller saddle angle than normal group on cephalograms and steeper inclination of the articular eminence than TMD and normal groups on transcranial radiographs. These results imply that the patients with the joint located more anterior and the articular eminence with steeper inclination might be riskier to TMJ open lock.

• The korean journal of orthodontics
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• v.36 no.3 s.116
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• pp.218-227
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• 2006

Although the submentovertex radiograph and surface EMG are not often used due to the difficulty of interpretation, they are accepted as useful diagnostic and analytic aids for skeletal asymmetry. There have been reports which state that they were also useful for the evaluation of vertical skeletal relations. The purpose of this study was to evaluate the correlations between EMG data, measurements from submentovertex radiographs, facial types and facial asymmetry following examination of 60 asymmetric patients. The radiographic corpus length were greater in the nonaffected sides (p<0.001), gonion to interspinosum axis were greater in the affected sides and the mandibular condyle and gonion were located more anteriorly in the non-affected sides than in the affected sides but not significant (p=0.07). The activity of the anterior temporal muscle in rest position was higher in the affected sides than in the non-affected sides (p<0.01). The activity of the masseter muscle at maximum clenching was found to be nonsignificant but it was higher in the affected sides than in the non-affected sides (p=0.09). There was positive correlation between facial index and the intercondylar axes angle (p<0.01). There was positive correlation between masseter muscle activity in maximum occlusion and facial index in the affected and non-affected sides (p<0.05). The results demonstrate that the submentovertex radiograph and EMG can provide useful information for the evaluation of horizontal and vertical skeletal relations.

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.59-69
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• 2002

The purpose of this study was to evaluate the reproducibility of lateral cephalometric landmarks according to radiographic image enhancement, and to contribute to the identification of cephalometric landmarks. Lateral cephalograms of ten individuals were taken and stored into computer. The images were then enhanced up to four grades by Quick Ceph Image Pro$^{TM}$ on condition that the gray-scale equalization number was 50 and the detail enhancement number was 50. After thirty two landmarks were identified on monitor images by five observers, the deviations from the mean, the distances estimated between identified points and the mean point of five identified points, were evaluated for each landmark at each enhancement grade. Through the statistical analysis, following results were obtained. 1. In case of unenhanced radiographic images, the inter-observer reproducibility of the landmarks showed a large variation. 2. The comparison of deviation from the mean according to the degree of radiographic image enhancement for each landmark showed that the inter-observer reproducibility was significantly different at 5 landmarks. 3. The landmark of pterygomaxillary fissure showed higher reproducibility at enhancement grade 1 and 2 images than at unenhanced images. So did the landmark of posterior nasal spine at enhancement grade 1 images, and the landmark of menton at enhancement grade 2, 3 and 4 images respectively. The above results suggest that the reproducibility of some landmarks can be increased by radiographic image enhancement during the identification of the lateral cephalometric landmarks on the monitor.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.900-913
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• 1998

Despite of technical difficulties, the combination of occlusal projection and densitometric digital analysis may ultimately provide a means of detection of subtle bone loss at the facial and lingual side of dental implant (Oblique occlusal view is more useful for $ITI^{(R)}$ dental implant due to its contour of shoulder as like tulip flower). In this study, conventional periapical projections of x-ray beam had shown more high sensitivity to detect the bony defects than oblique occlusal projections in alveolar crest obscured by dental implants or not, even if the difference was not statistically significant. Unlike conventional periapical projections. occusal projections combined with densitometric digital analysis technique may provide a means for detection of subtle bone change at the all around of implants without obscuring effect by implant itself. Although the results from this in vitro study were performed under limited circumstances, these results might afford more possibility and versatile modality of diagnosis options to clinician in the implant practice.

• The korean journal of orthodontics
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• v.37 no.5
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• pp.319-330
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• 2007

Defining right and left side differences in mandibular ramus height is one of the key elements in the diagnosis of facial asymmetry. The purpose of the present study was to evaluate the effect of correction of ramus height with frontal and lateral ramal inclinations (FRI and LRI) in 2-dimensional cephalograms and observe how this affects the diagnostic accuracy of asymmetry. Methods: Frontal and lateral cephalograms were obtained in 40 individuals with chin deviation. FRI and LRI were measured on each side and ramus height measurement was corrected with these inclinations using Pythagorean's theorem. The results of diagnosis before and after correction on cephalograms were compared with the results in 3D CT images. Results: Both FRI and LRI showed greater values in the contralateral side than in the chin-deviated side and these contributed to an increase in the right and left side ramus height differences. After comparison of diagnostic results before and after correction on cephalograms with the results on 3D CT images, the sensitivity increased significantly (from 74 to 94 %) whereas the specificity decreased (from 44 to 22 %). Overall accuracy increased from 68 to 78 % with the correction using FRI and LRI. Conclusions: The results of the present study indicate that correction of ramus height with FRI and LRI is useful for an accurate diagnosis of facial asymmetry on frontal cephalograms.

• 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.