• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.225-234
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• 1998

We used five adult dog mandibles embedded in resin block and six different cross-sectional planes for each mandible were choosen. According to the angle of mandibular occulsal plane to vertical plane(mandibular angle) and gantry angle of CT machine, we classified 4 experimental groups and 1 control group. The control group images were taken at the mandibular angel 0° and gantry angle 0°. The experimental images were taken at the mandibular angle 15° and gantry angle 0°(group 1); 30° and 0°(group 2); 15° and 15°(group 3) ;30° and 30°(group 4), respectively. Using the reformatted cross-sectional images, the distance from the mandibular canal to the alveolar crest and the distance from the mandibular canal to the buccal cortex and to the lingual cortex was measured and compared. The obtained results were as follows: 1. The distance from the mandibular canal to the alveolar crest of group 1 and 2 was larger than control group, but the distance of group 3 and 4 was smaller. The distance from the mandibular canal to the buccal cortex and to the lingual cortex of all experimental groups was smaller than control group. 2. The distance from the mandibular canal to the alveolar crest showed the largest difference from control group in all experimental groups, especially in group 2 and 4(p<0.05). 3. In the distance from the mandibular canal to the alveolar crest, the number of deviation value under 1 mm was 20 in group 3 and was 11 in group 2 and 4, respectively. 4. The deviation value of the distance from the mandibular canal to the buccal cortex and to the lingual cortex was under 1 mm in most cases.

• Imaging Science in Dentistry
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• v.32 no.3
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• pp.123-127
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• 2002

Purpose : To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. Materials and Methods: Thirty-six teeth with 57 proximal surfaces were radiographied using a size #2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. Results: The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. Conclusion: The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.13 no.1
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• pp.97-105
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• 1983

For the assessment of changes in the bone architecture of the maxilla and mandible in renal osteodystrophy, 31 chronic renal failure patients who were undergoing hemodialysis therapy were selected. They were evaluated through clinical oral examination, radiographic and biochemical examination. The results were as follows: 1. In 17 cases (54.8%), there were evidences of bony change in jawbone. 2. The most common dental radiographic finding was decreased bone density (14 cases, 45.2%). 3. The second most common dental radiographic finding was total or partial loss of lamina alveolar dura (11 cases, 35.5%). 4. The third most common dental radiographic finding was total or partial loss of inferior canal wall (8 cases, 25.8%). 5 cases showed evidences of bony change only in jawbone, and 5 cases only in hand, and 12 cases in both. 6. Serum creatinine, urea nitrogen and alkaline phosphatase values in hemodialysis group were much higher than in control group. 7. There were statistically significant correlation between bone density and lamina dura, and inferior alveolar canal wall.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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• pp.109-118
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• 1991

The author studied the age distribution, etiology, affected site and several radiographic features of periapical granulomas, cysts, and abscesses. The material consisted of 928 films obtained from the patients who were diagnosed and treated under the diagnosis of periapical granulomas, cysts, and abscesses during the past 8 years (1979-1986) at the Infirmary of Dental School, Chosun University. The obtained results were as follows: 1. The order of incidence was as follows: periapical abscess (67.2%), granuloma, and cyst. 2. The age distribution revealed the highest incidence around the age of 30 and relatively higher incidence over the age of 60 in the case of periapical abscess and granuloma. 3. In the frequency of location: Periapical abscesses occured most frequently in the mandibular molars. Granulomas showed relatively higher incidence in maxilla than in mandible. Cysts were most common in the maxillary anterior teeth. 4. The mean diameter of dental granuloma was 5.9㎜, however, all dental granulomas were less than 9.3㎜ in diameter. The mean diameter of periapical cyst was l3.8㎜. 5. Periapical cyst revealed well circumscribed radiolucent lesions and 77.8% of the lesion showed white line. 86.0% of dental granuloma showed well circumscribed border, 54.5% sclerosis on surrounding bone and 38.5% partial white line. Periapical abscess revealed diffuse radiolucent lesion, 89.6% of the lesions had sclerosis on surrounding bone, and 38.0% sinus tract.

• Imaging Science in Dentistry
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• v.35 no.2
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• pp.87-90
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• 2005

Purpose : The purpose of this study was to investigate variability of doses with same exposure parameters and evaluate radiographic density according to the variability of doses. Materials and methods Twenty-eight MAX-GLS (Shinhung Co, Seoul, Korea), twenty-one D-60-5 (DongSeo Med, Seoul, Korea), and eleven REX-601 (Yoshida Dental MFG, Tokyo, Japan) dental x-ray machines were selected for this study Surface doses were measured under selected combinations of tube voltage, tube current, exposure time, and constant distance 42 cm from the focal spot to the surface of the Multi-O-meter (Unfors Instruments, Billdal, Sweden). Radiographic densities were measured on the films at maximum, minimum and mean surface doses of each brand of x-ray units. Results With MAX-GLS, the maximum surface doses were thirteen to fourteen times as much as the minimum surface doses. With D-60-S, the maximum surface doses were three to eight times as much as the minimum surface doses. With REX-601, the maximum surface doses were six to ten times as much as the minimum surface doses. The differences in radiographic densities among maximum, mean, and minimum doses were significant (p<0.01). Conclusion : The surface exposure doses of each x-ray machine at the same exposure parameters were different within the same manufacturer's machines.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.41-44
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• 2018

Purpose: To evaluate the effect of different numbers of basis images and the use of metal artifact reduction (MAR) on the production and reduction of artifacts in cone-beam computed tomography images. Materials and Methods: An acrylic resin phantom with a metal alloy sample was scanned, with 450 or 720 basis images and with or without MAR. Standard deviation values for the test areas (around the metal object) were obtained as a way of measuring artifact production. Two-way analysis of variance was used with a 5% significance level. Results: There was no significant difference in artifact production among the images obtained with different numbers of basis images without MAR (P=.985). MAR significantly reduced artifact production in the test areas only in the protocol using 720 basis images (P=.017). The protocol using 450 basis images with MAR showed no significant difference in artifact production when compared to the protocol using 720 basis images with MAR (P=.579). Conclusion: Protocols with a smaller number of basis images and with MAR activated are preferable for minimizing artifact production in tomographic images without exposing the patient to a greater radiation dose.

• Imaging Science in Dentistry
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• v.49 no.3
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• pp.241-249
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• 2019

Ameloblastoma is a benign locally invasive tumor with a high tendency to recur. It is considered rare in the pediatric population, with most cases diagnosed in the third to fifth decades of life. Approximately 80% of ameloblastomas occur in the molar and ramus region of the mandible, while 20% of cases occur in the maxillary posterior region. This report presents a case of plexiform ameloblastoma in an uncommon location in an 8-year-old child. The lesion was initially thought to be a dentigerous cyst, based on its location and radiographic appearance. The clinical and radiographic features, histopathology, and treatment of solid, plexiform, maxillary ameloblastoma are reviewed, with an added emphasis on a literature review of ameloblastoma in children. This report emphasize the importance of long-term follow-up, since recurrence may occur many years after initial tumor removal.

• Imaging Science in Dentistry
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• v.49 no.4
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• pp.307-315
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• 2019

This report describes 3 cases of cleidocranial dysplasia (CCD) and presents relevant findings on long-term follow-up radiographic images of impacted permanent teeth with delayed eruption. Radiographic images of 3 CCD patients were reviewed retrospectively. These images were mainly composed of panoramic and skull radiographs, and the follow-up periods were 3, 13, and 13 years, respectively. The distinct features revealed by the images were described, and the eruption state of impacted permanent teeth was evaluated. The features common to the 3 cases were multiple supernumerary teeth, the presence of Wormian bone, underdevelopment of the maxilla and the maxillary sinus, and clavicular hypoplasia. The eruption of impacted permanent teeth was not observed without proper dental treatment in adult CCD cases, even after long time periods had elapsed. When proper orthodontic force was applied, tooth movement was observed in a manner not significantly different from the general population.

• Imaging Science in Dentistry
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• v.39 no.3
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• pp.169-173
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• 2009

The calcifying odontogenic cyst (COC) is a rare disorder of the jaws and shows various radiographic features. The purpose of this study is to describe the different radiographic appearances of 2 cases of COC. Case 1 was located in the posterior maxilla extending into maxillary sinus, showing unilocular radiolucency with a well-defined margin. Cortical bone expansion and thinning were prominent. Root resorption of adjacent teeth was apparent. Case 2 showed unilocular radiolucency with a calcified material. Calcification was supposed to be dystrophic dental hard structures, detected at the periphery of the lesion. Ghost cell and proliferation of ameloblastoma-like tissues were common features for these two lesions on histopathological findings. This reports presented common and atypical radiographic features of the COC.

• Imaging Science in Dentistry
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• v.30 no.1
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• pp.55-62
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• 2000

Purpose: This study was performed to develop the electronic textbook (CD-rom title) about preclinical practice of oral and maxillofacial radiology, using multimedia technology with interactive environment. Materials and Methods: After comparing the three authoring methods of multimedia, i.e. programming language, multimedia authoring tool and web authoring tool, we determined the web authoring tool as an authoring method of our electronic textbook. Intel Pentium II 350 MHz IBM-compatible personal computer with 128 Megabyte RAM, Umax Powerlook flatbed scanner with transparency unit, Olympus Camedia l400L digital camera, ESS 1686 sound card, Sony 8 mm Handycam, PC Vision 97 pro capture board, Namo web editor 3.0, Photoshop 3.0, ThumbNailer, RealPlayer 7 basic and RealProducer G2 were used for creating the text document, diagram, figure, X-ray image, video and sound files. We made use of javascripts for tree menu structure, moving text bar, link button and spread list menu and image map etc. After creating all files and hyperlinking them, we burned out the CD-rom title with all of the above multimedia data, Netscape communicator and plug in program as a prototype. Results and Conclusions : We developed the dental radiology electronic textbook which has 9 chapters and consists of 155 text documents, 26 figures, 150 X-ray image files, 20 video files, 20 sound files and 50 questions with answers. We expect that this CD-rom title can be used at the intranet and internet environments and continuous updates will be performed easily.