• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.592.1-592
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• 2001

Conventional intraoral radiography continues to be the most widely used for the diagnosis of dental caries. But conventional intraoral film has several shortcomings, including processing error, increased radiation dose, etc. Recently, various digital radiographs substitude for conventional radiography to overcome these disadvantages. The digital radiographies are numerous advantages, including elimination of processing errors, lower radiation dose, image quality enhancements such as contrast and density modulation.(omitted)

• 대한치과의사협회지
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• 제57권1호
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• pp.26-33
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• 2018

Panoramic radiography is widely used as a primary radiological diagnosis in dentistry. However, due to the overlapping of anatomical structures, diagnostic capability of panoramic radiography is limited. Recently, panoramic machine equipped with various image processing software has been introduced to improve the diagnostic capability. This study aims to introduce panoramic equipment with multi-layer imaging software that can provide 41 images from anterior to posterior in region of interest, and to report in various clinical applications.

• Imaging Science in Dentistry
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• 제47권3호
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• pp.199-207
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• 2017

Purpose: Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space. Materials and Methods: Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms. Results: Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter. Conclusion: Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary.

• Imaging Science in Dentistry
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• 제36권1호
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• pp.25-32
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• 2006

Purpose : To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. Materials and Methods : An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined In each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Results : Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and - 0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlation with clinical bone quality classification with correlation coefficients -0.506 significantly (p<0.05). Conclusion : This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites.

• 대한소아치과학회지
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• 제37권1호
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• pp.13-23
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• 2010

기존 DIFOTI 시스템의 문제점 중 디지털 영상 처리의 개선을 위하여 light emitting diode(LED)를 광원으로 사용하여 prototype DIFOTI 시스템을 개발하였다. 효율적이고 우수한 화질을 제공 할 수 있는 광량을 산출하기 위해 1일부터 20일까지 유치 법랑질을 Carbopol 907 인공 우식 용액을 사용하여 탈회시키고 실험 기간에 따른 법랑질 탈회 정도를 기존의 $DIFOTI^{TM}$ 시스템과 영상 분석을 통해 비교 평가하였으며, 탈회 정도에 대한 gold standard로 사용된 편광 현미경 소견과 비교하여 다음과 같은 결론을 얻었다. 1. 탈회 기간에 따라 두 시스템 모두 탈회 법랑질의 광도가 감소하는 양상을 보였다. 2. 정상 및 탈회 법랑질간의 광도의 차이는 $DIFOTI^{TM}$ 시스템이 prototype DIFOTI 시스템보다 더 큰 값을 보였다. 3. 편광현미경 관찰 소견과 비교해 볼 때, $DIFOTI^{TM}$ 시스템은 병소 깊이와 매우 유사한 변화 양상을 보여준 반면, prototype DIFOTI 시스템은 병소 깊이의 변화를 충분히 반영하지 못하였다. 보다 우수한 영상을 얻기 위해서는 광량의 최적화 과정과 함께 디지털 카메라의 조리개 조절도 병행되어야 할 것으로 판단되며, 이러한 단점은 소프트웨어적인 보완을 통해 개선될 수 있을 것으로 사료된다.

• 한국컴퓨터정보학회논문지
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• 제9권4호
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• pp.133-139
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• 2004

본 연구에서는 치과용 디지털 X-ray 영상의 기하학적인 분석을 통한 자연치아 주위염 분리에 관한 방안을 제안한다. 제안된 방법은 치아의 기하학적인 분석을 통하여 예상되는 환부를 분리하고, 분리된 환부를 중심으로 다중 템플릿의 에지 기반 정합을 수행함으로써 환부 이외 지역에서 발생되는 오류 정보를 최소화 하였으며, 차정보 생성시 수치적인 근거를 제시함으로써 결과의 일관성 및 객관성을 갖도록 하였다. 실험 결과, 인간의 시각으로 판별하기 어려운 미세한 차이의 표시 및 환부의 이상 발생 여부를 확연히 구분할 수 있었고, 실용 시스템으로의 이용이 가능함을 확인하였다.

• 대한치과기공학회지
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• 제25권1호
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• pp.21-28
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• 2003

The purpose of this study was to process bio-active glass ceramic composite, reinforced with sapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, and the mechanical properties. Glass raw materials melted in Pt crucible at 1300$^{\circ}C$ during 3.5 hours. The melt was crushed in ball mill and then crushed material, ground and sieved to $<40{\beta}{\mu}m$. Sapphire fibers cut (30mm) and aligned. Powder and fibers hot pressed. The micrographs show good bonding between the matrix and the fiber and no porosity in the glass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This is indication of good fracture strength. EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrix showing crystalline phase. Also diffraction pattern of TEM showing the crystalline phase and more than one phase. Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% sample was approximately 69MPa, while strength of the control sample is 35MPa. Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

• 치위생과학회지
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• 제20권4호
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• pp.245-251
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• 2020

Background: This study tries to compare and analyze the removal effect of dental plaque of general dentifrice and pregnant women's dentifrice and quantify the results to provide basic data so that consumers can make reasonable choices when purchasing dentifrice, and also increase interest in the dental plaque. Methods: After forming a dental plaque (carbohydrate porridge) on the labial surface of the bovine teeth, a disclosing agent was applied. Then the same experimenter brushed the surface of the bovine teeth using an electric toothbrush and took photographs using a DSLR camera. Thereafter, the residual amount of dental plaque was analyzed using the ImageJ program, and SPSS 26.0 was used for statistical processing. Results: The average residual amount of dental plaque using the general dentifrice was 11.71% for Perio, 9.45% for Cliden, and 8.47% for 2080, and the average residual amount for the three types was approximately 9.88%. The average residual amount of dental plaque of pregnant women's dentifrice was 13.95% for Jeninmothers, 12.53% for Tntnmoms, and 12.63% for Mommiracle, and the average residual amount of the three types was approximately 13.04%. On comparing the average residual amount of dental plaque between general and pregnant women's dentifrices, it was observed to be 3.16% higher for the latter. However, the results were not statistically significant. Conclusion: According to the research results, there was no significant difference in removal effects of general dentifrice and pregnant women's dentifrice. In addition, when a pregnant woman uses the right toothbrushing method with pregnant women's dentifrice, it can prevent or inhibit the progression of the gestational periodontal disease. Therefore, we recommend pregnant women to use pregnant women's dentifrices.

• 대한치과기공학회지
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• 제24권1호
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• pp.73-81
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• 2002

Accurate acquisition of surface geometries such as machined surfaces, biological surfaces, and deformed parts have been very important technique in scientific study and engineering, expecially for system design, manufacturing and inspection. Two camera method is relatively simple with an acceptable accuracy. In this paper, a new method is studied to acquire 3D geometric data of the small object such as a die in stone model. When the devices, cameras, laser beam and object are in a perfect plane, the calculation becomes very simple with less error. But this paper shows that arbitrarily positioned system can also be used to obtain 3D data.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.325-333
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• 2023

Purpose: The objective of this study was to evaluate and compare the accuracy and image quality of root surface area (RSA) measurements obtained with various cone-beam computed tomography (CBCT) protocols, relative to the gold standard of micro-computed tomography (CT), in an in vitro setting. Materials and Methods: Four dry human skulls were scanned using 8 different protocols, with voxel sizes of 0.15 mm, 0.3 mm, and 0.4 mm. Three-dimensional models of the selected teeth were constructed using CBCT and microCT protocols, and the RSA was automatically measured by the image-processing software. The absolute difference in the percentage of the RSA(%ΔRSA) was calculated and compared across the 8 CBCT protocols using repeatedmeasures analysis of variance. Finally, image quality scores of the RSA measurements were computed and reported in terms of percent distribution. Results: No significant differences were observed in the %ΔRSA across the 8 protocols (P>0.05). The deviation in %ΔRSA ranged from 1.51% to 4.30%, with an increase corresponding to voxel size. As the voxel size increased, the image quality deteriorated. This decline in quality was particularly noticeable at the apical level of the root, where the distribution of poorer scores was most concentrated. Conclusion: Relative to CBCT protocols with voxel sizes of 0.15mm and 0.3mm, the protocols with a voxel size of 0.4 mm demonstrated inferior image quality at the apical levels. In spite of this, no significant discrepancies were observed in RSA measurements across the different CBCT protocols.