• Imaging Science in Dentistry
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• 제44권3호
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• pp.249-252
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• 2014

Glandular odontogenic cyst (GOC) is a rare, potentially aggressive jaw lesion. The common radiographic features include a well-defined radiolucency with distinct borders, presenting a uni- or multilocular appearance. A cystic lesion in the posterior mandible of a 78-year-old female was incidentally found. Radiographs showed a unilocular lesion with a scalloped margin, external root resorption of the adjacent tooth, and cortical perforation. This lesion had changed from a small ovoid shape to a more expanded lesion in a period of four years. The small lesion showed unilocularity with a smooth margin and a well-defined border, but the expanded lesion produced cortical perforation and a lobulated margin. The provisional diagnosis was an ameloblastoma, whereas the histopathological examination revealed a GOC. This was a quite rare case, given that this radiographic change was observed in the posterior mandible of an elderly female. This case showed that a GOC can grow even in people in their seventies, changing from the unilocular form to an expanded, lobulated lesion. Here, we report a case of GOC with characteristic radiographic features.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제15권2호
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• pp.137-145
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• 1993

The purpose of this study was to observe the effect on teeth and tibia bone histopathologically in rats by the richitogenic diet. For this purpose, 48 sprague-dewley rats, weighing 80g or more, divided into 6 groups, and sacrificed on the 1st, 2nd, 3rd, 4th, 5th, 6th weeks after experiments respectively. The tissues contain tooth, and tibial bone were fixed in 10% normal formalin solution, decalcified in Plank-Rychlo solution, embedded in paraffin, sectioned in $6-8{\mu}$ as usual manner, the tissues were stained in hematoxylin eosin, and examined hisopathologically. Follow results were attained 1. Pyknotic appearance of odontoblastic layer was noticed on the 1st week, and increased on the 2nd weeks, and it is appeared that degeneration and dearrangements of odontoblasts on the 4 weeks. But a little recovered on the 6th weeks. 2. The thickness of predentin layer was increased on the 2nd weeks, and increased remarkedly on the 3rd weeks and reached the maximum on the 5th weeks. 3. The interglobular dentin was appeared in spotty shape on the 2nd weeks, and increased on the 4th, 5th, weeks, and large amount of inter-globular dentin was appearanced on the 6th weeks. 4. It is appeared that enamel hypoplasia on the 4th weeks. 5. Epiphyseal and metaphyseal plate of tibia was increased from/on the 2nd weeks, increased maximumly on the 5th weeks. And pyknotic, dearrangements, and hyperchromatic appearances of chondrocytes on the plate were increased on the 1st week.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.454-461
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• 2004

The purpose of this study is to compare and to evaluate the effects of the degree of saturation on the progression of artificial root caries lesion. A total of 8 human premolars without any defects and cracks selected and the cementum were removed and the teeth were cleaned with ultrasonic device and pumice without fluoride. Each tooth was sectioned into 6 pieces and they were ground with #800 sandpaper until they had a thickness of 200pm. Specimens were applied with nail vanish except for the 2-3 mm window area after application of bonding agent. Under the constant pH, the specimens were divided into 6 groups (degree of saturation: 0.1415, 0.1503, 0.1597, 0.1676, 0.1771. 0.1977). Each group was immersed in acid buffer solution for 1. 2, 3, 5 days under controlled temperature ($25^{\circ}C$) and imbibed in water and examined using the polarizing microscope. The results were as follows 1. Although the degree of saturation of demineralization solution decreased, the depth of penetration in the dentin was constant. 2. Erosion was observed on the surface of all the teeth in the group I, II. In the group III, IV, V, surfaces were not changed. The teeth in the group VI showed the more mineralized surface but not the shape of the dentinal tubules distinctively. 3. In all groups, the lesion progressed rapidly at the first day of the experiment, but increased gradually as time elapsed.

• 대한치과보철학회지
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• 제42권2호
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• pp.125-132
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• 2004

Statements of problem: All ceramic fixed partial denture cores can be made by the slip casting method and the advanced alumina tape method. The fracture resistance of these core connector areas is relatively low. Purpose: The purpose of this study is to standardize the appropriate volumetric figure and location of the connectors in the alumina core fabricated in alumina tape to be used in fixed partial dentures by way of topology optimization. Material and method: A maxillary anterior three-unit bridge alumina core with teeth form and surrounding periodontal apparatus model was used to ultimately design the most structurally rigid form of the connector. Loadings from a $0^{\circ}$, $45^{\circ}$ and $60^{\circ}$ to the axis of each tooth were applied and analyzed with the 3-D finite element analysis method. Using the results from these experiments, the topology optimization was applied and the optimal reinforcement layout of connector was obtained and the detail shape in the fixed partial denture core was designed. Results: The modified prosthesis with the form of a bulk in the lower lingual surface of the connector in the event, reduced the stress concentration up to 20% in the 3-D FEA. Conclusion: The formation of a bulk in the lower lingual connector area of an alumina core for a fixed partial denture decreases the stress to a clinically favorable measure but does not harm the esthetic point of view. This result illustrates the possibility of clinical application of the modified form designed by the topology optimization method.

• 대한치과보철학회지
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• 제36권1호
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• pp.120-132
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• 1998

This stusy was to investigate the marginal fitness of porcelain-fused-to- metal crown after succesive firing cycle. Main variables were the degree of marginal curvature of labiocervical margin and the type of alloy. The exaggerated marginal curvature(EMC) was created by additional reduction at the faciocervical wall of the normallized marginal curvature (NMC)-typed ivorine tooth by using milling machine. The difference in the shape was the mid facial margin was placed 2mm apical to cemento- enamel junction in labial surface. Three types of alloy were high noble, noble, and base metal alloy. Test specimens were divided into 8 groups and each group had 8 specimens. Sixty four ceramometal crowns were made totally. Measurement stages were following degassing, opaquing. body porcelain firing, and glazing, and measuring sites were 4. (midmesial, midfacial, middistal, and midlingual). Digital, travelling measuring microscope (0.5 um precision, Olympus. Japan) was used under ${\times}250$ magnification. Within the limitation of this investigation, it was concluded as belows: 1. The pattern of marginal distortion was varied. Degassing stage was not a specific, causative stage that induce most of total marginal distortion during whole procedure fabricating a ceramometal crown. Body firing stage induced discrepancy relatively more than other firing stages. 2. The specimens that were Ni-based alloy and had EMC were distorted persistently following successive fabricating procedures. But marginal openings were decreased after glazing. 3. The release of metal grinding-induced stress was presumed as a cause that induce marginal distortion. 4. The amount of discrepancies of the labial and lingual margins were greater than that of the mesial and distal margin in the specimen that had EMC. 5. Silver-plated die was not enough to resist abrasion during repeated seating of metal copings on the die-holding device.

• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.171-182
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• 2017

In this study, the internal structure of a Heumgyeonggak-nu (欽敬閣漏) was designed, and the power transmission mechanism was analyzed. Heumgyeonggak-nu is an automated water clock from the Joseon Dynasty that was installed within Heumgyeonggak (欽敬閣), and it was manufactured in the $20^{th}$ year of the reign of King Sejong (1438). As descriptions of Heumgyeonggak-nu in ancient literature have mostly focused on its external shape, the study of its internal mechanism has been difficult. A detailed analysis of the literature record on Heumgyeonggak-nu (e.g., The Annals of the Joseon Dynasty) indicates that Heumgyeonggak-nu had a three-stage water clock, included a waterfall or tilting vessel (欹器) using the overflowed water, and displayed the time using a ball. In this study, the Cheonhyeong apparatus, water wheel, scoop, and various mechanism wheels were designed so that 16 fixed-type scoops could operate at a constant speed for the water wheel with a diameter of 100 cm. As the scoop can contain 1.25 l of water and the water wheel rotates 61 times a day, a total of 1,220 l of water is required. Also, the power gear wheel was designed as a 366-tooth gear, which supported the operation of the time signal gear wheel. To implement the movement of stars on the celestial sphere, the rotation ratio of the celestial gear wheel to the diurnal motion gear ring was set to 366:365. In addition, to operate the sun movement apparatus on the ecliptic, a gear device was installed on the South Pole axis. It is expected that the results of this study can be used for the manufacture and restoration of the operation model of Heumgyeonggak-nu.

• 대한소아치과학회지
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• 제34권4호
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• pp.646-650
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• 2007

2003년 4월부터 2006년 4월까지 안양 지역에 위치한 개인 소아치과 병원에 내원한 환아 7038명을 대상으로 임상적, 방사선학적 검사를 통해 성별, 상악 정중과잉치의 수, 치관의 형태와 위치, 치관 방향을 조사하여 다음과 같은 결론을 얻었다. 1. 과잉치를 가진 환아는 239명으로 3.40%(총 241명, 3.42%)에 해당하였고 총 289개의 과잉치가 있었다. 2. 과잉치는 1개 있는 경우가 191명으로 가장 많았고, 2개 있는 경우도 48명 있었으며, 3개 이상 있는 경우는 없었다. 3. 상악 정중과잉치는 3.2:1로 여아보다 남아에서 호발하였다. 4. 과잉치는 왼쪽에 있는 경우가 55.4%로 약간 더 많았고, 모양은 원추형, 방향은 역위형이 가장 많았다. 5. 하악 정중과잉치는 2명에서 관찰되었다.

• 구강회복응용과학지
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• 제34권3호
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• pp.225-231
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• 2018

다운증후군 환자는 일반적으로 구강 관리에 대한 인식과 수행능력의 부족으로 구강위생상태가 불량하며, 치아 상실의 위험이 높다. 또한 작고 불규칙한 치아, 부분 무치증의 구강 내 특징으로 보철 치료에 어려움이 있다. 본 증례는 다운증후군 환자에서 상악 무치악 부위의 임플란트 하이브리드 보철 치료에 대한 케이스를 보고하고자 한다. 최종보철물의 외형은 하악 잔존치와 인공치를 조화롭게 설정하여 결정하였고, 위생관리가 용이하도록 가공치부위를 수정하였다. 결과적으로 심미적, 기능적으로 만족스러운 결과를 얻었기에 이를 보고하고자 한다.

• 식물분류학회지
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• 제32권4호
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• pp.397-416
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• 2002

한국산 제비꽃속 노랑제비꽃절 (Viola section Chamaemelanium) 식물에 대해 광학현미경 및 전자현미경을 사용하여 형태 분류학적 연구를 수행하였다. 지하경과 지상경의 특징, 자방 돌기 그리고 주두의 모양과 돌기 등의 특징에 의해 V. orientalis와 V. brevistipulata가 구별되었다. 나아가 후자는 잎의 특징에 따라 3 변종 즉 var. brevistipulata, var. minor 그리고 var. laciniata 등으로 세분되었다. Viola brevistipulata var. laciniata는 거치 수가 가장 많고, 불규칙한 치상의 복거치를 갖는다. 그러나 다른 두 변종은 규칙적인 파상 또는 치상의 거치를 갖는다. 세 변종간 잎의 크기는 V. brevistipulata var. brevistipulata가 가장 크고 V. brevistipulata var. minor가 가장 작다. 이들 중 V. brevistipulata var. laciniata는 한국 미기록 종이다. 또한 자방과 주두에 발달된 돌기물의 모양 및 배열양상은 본 절내 종을 동정할 때 중요한 표징형질로 확인되었다.

• 대한치과기공학회지
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• 제39권4호
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• pp.235-242
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• 2017

Purpose: The aim of this study was to evaluate the marginal and internal gap of zirconia copings fabricated by CAD/CAM system and to research the effect of cement space on the fit of zirconia prosthesis. Methods: Zirconia copings were designed using 3shape software and then milled from presintered zirconia blocks by Kavo dental milling machine. The cement space was set at $0{\mu}m$ around the margins for all groups, and additional cement space appling 1 mm above the finish lines of tooth. The samples were classified into 4 groups according to the cement space setting(Cs-0, Cs-40, Cs-80, Cs-120). Replica technique used to investigate marginal and internal gap. The silicone film thickness was recorded using a optical microscope with image software analysis system at 75${\times}$magnification. The assessment performed on the six points in bucco-lingual and mesio-distal sections(4 groups, 10 copings per group, 12 measuring points per coping). The data were statistically analyzed with one-way ANOVA followed by pair-wise Tukey's post hoc tests(${\alpha}$<0.05). Results: Better marginal and internal fit values were exhibited by $80{\mu}m$ cement space. The results showed that different cement space values had statistically significant effect on the marginal and internal gap of zirconia copings(p<0.001). The gap of margin and axial wall area was smaller than that the gap of occlusal area in all groups(p<0.001). Conclusion : Effect of different cement spaces on the marginal and internal gap of zirconia copings.