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The aim of this investigation was radiographic and histologic evaluations of the 3D reconstructed root analogue implant(RAI) placed in extraction sockets of maxillary incisor of Sprague-Dawley(SD) rats. Thirteen male 10-week-old SD rats were used in this study. Using a Micro computed tomography(μCT) scan, maxillary incisor images of the SD rat were obtained. CT images of the incisor were converted to the STL(standard triangulation language) format and RAIs were 3D-printed. The replicas were made of ABS(acrylonitrile butadiene styrene) and PLA(polylactic acid). Each replica was coated with titanium for the protection barrier. Surface morphology and thickness of coating were analyzed by the SEM(scanning electron microscope). Incisor replicas were placed into extraction sockets after a tooth extraction. After 4 weeks, rats were sacrificed and radiographic images were taken. Decalcified sections were prepared for a light microscopic study. Incisor replicas fitted into the extraction socket due to its congruence with the socket. Rats were well fed for 4 weeks without the inflammation. Radiographic images did not show any particular evidence of the bone resorption. The histometric evaluation on RAIs of ABS, PLA showed a mean mineralized bone-to-implant contact of 45.3±14.2% and 37.2±5.5%, respectively. The present data suggests that titanium coating enables osseointegration and makes polymer material possible as an dental implant.
The purpose of this study was to investigate the antibacterial effect of inorganic-silver particle on the conventional dental composite. Two antibacterial silver particles (Novaron and INC-ZRS) and silica were adopted to the filler system. A visible light system of camphorquinone photo-initiator and 2-(dimethylamino)ethyl methacrylate photo-accelerator was utilized to activate the resin matrix in the polymer composites. The degree of conversion, depth of cure, mechanical strength and antibacterial properties of dental composites were investigated. Two silver antibacterial agents could inhibit the growth of the major oral pathogen Streptococcus mutans. There was no significant difference in mechanical strength. However, there was a significant decrease in depth of cure for the INC-ZRS group. These results indicate that a dental resin composite incorporating silver antibacterial agent may be useful clinically because of its inhibitory effect against Streptococcus mutans and its favorable mechanical properties. Further study should be done to overcome the color instability and to demonstrate the biological stability.
The purpose of this study was to investigate the effect of adding antibacterial silver-doped phosphate glasses on the antibacterial properties of conventional dental composite. Silver-doped phosphate antibacterial glasses were prepared by the melting method. The antibacterial effects of some undoped and silver-doped glasses of composition 60P₂O?-30CaO-(10-x)Na₂O-xAg₂O, (where x=0, 1, 1.5, 2 mol %), against Staphylococcus aureus, Escherichia coli and Streptococcus mutans micro-organism using agar diffusion test and mininum inhibitory concentration test were investigated. A visible light system of camphorquirione photo-initiator and 2-(dimethylamino)ethyl methacrylate photo-accelerator was utilized to activate the resin matrix in the polymer composites, The degree of conversion, depth of cure, mechanical strength and antibacterial properties of dental composites with glass powder and resin matrix were investigated. Silver-doped glasses showed an increase in inhibition zone diameter against the tested micro-organisms, Composite groups that contain small amounts of phosphate glasses (Group 0~3) demonstrated no significant difference in compressive and flexural strength, but composite that has maximum filler use With phosphate glass (Group 4) showed severe decrease in both mechanical strength. There was no significant difference in degree of conversion. However, there was significant decrease in depth of cure for the Group 4. Silver-doped phosphate antibacterial glasses inhibited the growth of the major oral pathogen S. mutans. But there was no significant difference in antibacterial effects when they mixed into dental composite. These results indicate that a dental resin composite With 2 % Ag-doped phosphate glass may not be useful clinically because its insufficient anticariogenic effect, even though it showed favorable mechanical strength and polymeric behavior. Further study should be needed to overcome the low antibacterial effect and to establish the effective mechanism and dynamic model for the anti anticariogenic composite resin.
플립드 러닝(flipped learning)은 온라인 및 오프라인을 포함한 둘 이상의 상이한 학습 환경을 혼합하여 학습 효과를 극대화 할 수 있는 새로운 학습 테크닉으로써, 최근 등장한 ‘Google classroom' 서비스는 플립드 러닝에 최적화된 토탈 솔루션이다. 본 연구는 국내 최초로 D 치과대학 치의학과 본과 2학년 학생들 70명에게 구글 클래스룸 플랫폼을 이용한 플립드 러닝을 적용 후 학생들의 만족도를 평가하였다. 치주과학 개론 및 치과보존학 아말감 수복학 두 과목을 선정하여 6회의 강의 중 3회는 전통적 수업방식으로, 나머지 3회는 구글 클래스룸을 포맷으로 한 플립드 러닝으로 진행하였다. 만족도 평가는 강의가 모두 완료된 후 설문을 통해 진행되었다. 본 연구를 통해, 치과대학 수업에의 플립드 러닝 적용은 이해도, 자기주도적 학습과 학습 동기면에서 높은 효율 및 만족도를 보였고 학생들은 매우 긍정적인 학습효과를 보였다. 결과적으로, 구글 클래스룸을 활용한 플립드 러닝은 치과대학 수업에서 효과적인 플랫폼임을 알 수 있었다. Flipped learning is a new learning technique which can maximize the learning effect by mixing two or more different learning environments including online & offline, and recently introduced system: ‘Google classroom' is the optimized internet platform for flipped learning. This study tried to apply flipped learning to regular course 2nd grade dental students(n=70) and evaluated the satisfaction of students. The subjects of periodontology and operative dentistry were chosen to evaluate flipped learning model for regular course 2nd grade dental students(n=70). Each class consisted of six classes, and three times of them were performed in conventional classes and the other three times were in flipped learning method by using Google classroom. Evaluation of satisfaction progressed at the end of class. In this study, application of flipped learning in the dental college classes showed high efficiency in terms of degree of understanding, self-directed learning and motivation. Collectively, it was shown that flipped learning using Google classroom can be a reliable platform in dental classes.
Osteoclasts regulate bone homeostasis and have a key role in bone degenerative processes. Mouse RAW264.7 macrophage cells have been shown to retain the capacity to differentiate into osteoclast-like cells in the presence of a receptor activator of nuclear factor kappa B ligand(RANKL), which is essential and sufficient to promote the maturation of osteoclasts. When treated with RANKL, RAW264.7 cells express high levels of osteoclastassociated genes such as tartrate-resistant acid phosphatase(TRAP), which has been widely used to assess bone resorption. In this study, we hypothesized that alendronate prevents RANKL-induced osteoclast-like cells, which are known to play important roles in the bone-resorptive responses. We investigated that occurred TRAP-positive area and the expression patterns of two important proteolytic enzymes, cathepsin K and Matrix Metalloproteinase- 9(MMP-9) during RANKL-induced osteoclast differentiation in RAW264.7 cells. These results showed that increased TRAP-positive staining and both cathepsin K and MMP-9 mRNA expression levels on RANKL-induced osteoclast differentiation during 4 days. Especially, alendronate increased caspase-3 expression for apoptosis with Western blot analysis. These results showed that alendronate cause apoptosis and thus osteoclast differentiation inhibit. This finding may help the understanding of the osteolytic and osteoporotic processes responsible for bone diseases, including osteoporosis and periodontal diseases.
김지현 ( Ji Hyun Kim ), 성정민 ( Jeong Min Seong ), 문호진 ( Ho Jin Moon ), 황지민 ( Ji Min Hwang ), 황경숙 ( Kyung Sook Hwang ), 권용대 ( Yong Dae Kwon ), 권일근 ( Il Keun Kwon ), 박용덕 ( Yong Duk Park ) 한국조직공학과 재생의학회 2010 조직공학과 재생의학 Vol.7 No.2
Osteoblasts mineralize bone matrix in the process of bone formation and osteoblastic differentiation is an important step of bone formation. Some drugs have useful effects for bone formation in oriental medicine. In this study, to confirm the anti-inflammation and osteoblast differentiation effect of Pharbitidis Semen extract used in oriental medicine, we investigated cell viability, Alizarin red S assay, and Alkaline phosphatase(ALP) activity with Pharbitidis Semen extract. Also, we studied the inhibition effect of nitric oxide(NO) generation with Pharbitidis Semen extract in RAW 264.7 cell. Our results showed that Pharbitidis Semen extract had almost no cytotoxicity to the cell and it significantly enhanced the induction of ALP activity and Alizarin red S staining for osteogenesis in MC3T3-E1 cell. Also, all Pharbitidis Semen extract inhibited the LPS-induced NO generation in RAW 264.7 cell. Especially, Pharbitidis Semen ethyl acetate extract and Pharbitidis Semen butanol extract showed to be powerful inhibitors of NO generation. In conclusion, Pharbitidis Semen extract increased the ALP activity, Alizarin red S assay activity for bone formation and attenuated NO generation for inflammation. These results suggest that Pharbitidis Semen extract may act as a successful drug for osteogenic differentiation in vitro and could have the potential to be use as a therapeutic agent for bone formation.
This study aims to introduce the method that can relieve vibrating forces to oral environment by making an embouchure aid. Thin plastic crown forms were fabricated to prevent tooth abrasion and irritation to lip mucosa for the saxophone player. After application to the player, the most comfort form was chosen and delivered to 3 professional saxophone players. After 5 mon, the players responded to the survey. This embouchure aid did not disturb playing and gave comfort to lower lip. In general, the players preferred thin soft type and thought it caused little effect on sound. Far too little attention has been paid to the problems encountered by single-reed wind instrumentalist who suffer from tooth abrasion and irritation to lip mucosa. The embouchure aid not only prevent tooth damage but also diminish the discomfort of tight embouchure.
Objectives: The aim of this study was to test the hypothesis, that the effectiveness of irrigation in removing smear layer in the apical third of root canal system is dependent on the depth of placement of the irrigation needle into the root canal and the enlargement size of the canal. Materials and Methods: Eighty sound human lower incisors were divided into eight groups according to the enlargement size (#25, #30, #35 and #40) and the needle penetration depth (3 mm from working length, WL-3 mm and 9 mm from working length, WL-9 mm). Each canal was enlarged to working length with Profile.06 Rotary Ni-Ti files and irrigated with 5.25% NaOCl. Then, each canal received a final irrigation with 3 mL of 3% EDTA for 4 min, followed by 5 mL of 5.25% NaOCl at different level (WL-3 mm and WL-9 mm) from working length. Each specimen was prepared for the scanning electron microscope (SEM). Photographs of the 3mm area from the apical constriction of each canal with a magnification of ×250, ×500, ×1,000, ×2,500 were taken for the final evaluation. Results: Removal of smear layer in WL-3 mm group showed a significantly different effect when the canal was enlarged to larger than #30. There was a significant difference in removing apical smear layer between the needle penetration depth of WL-3 mm and WL-9 mm. Conclusions: Removal of smear layer from the apical portion of root canals was effectively accomplished with apical instrumentation to #35/40 06 taper file and 3 mm needle penetration from the working length.