Surface Characterization, Antimicrobial Activity, and Biocompatibility of Autopolymerizing Acrylic Resins Coated with Reynoutria elliptica Extract

We conducted surface characterization to assess the biocompatibility and investigate the antimicrobial activity against oral pathogens in autopolymerizing acrylic resins, coated with light-curable coating resin, containing various concentrations of Reynoutria elliptica extract (0, 200, 400, and 600 mu g/mL). The R. elliptica extract powder was prepared using a freeze-drying technique. Further, a goniometer and microhardness tester were used to determine the water contact angle, and Vickers hardness, respectively; color measurements were performed on the uncoated and coated acrylic resin disks. The polyphenol content of the extracts from the coated acrylic resin disk was analyzed using UV-VIS spectroscopy. The antimicrobial activity of the coated acrylic resin disk against Streptococcus mutans and Candida albicans was observed for 24 and 48 h by measuring the optical density using spectrophotometry. In addition, biocompatibility was confirmed by testing the cell viability according to ISO 10993-5. The water contact angle, Vickers hardness, and color change values of the coated acrylic resin disks were not significantly different from the control. Polyphenol was detected in all experimental groups, with no significant differences between the experimental groups. The experimental groups exhibited significant antimicrobial activity against S. mutans and C. albicans compared to the control group, after 48 h of incubation. The cell viability between the control and experimental groups was not significantly different. The proposed coating resin containing R. elliptica extract is applicable on dental acrylic resins, due to their antimicrobial properties and excellent biocompatibility, with no deterioration of surface characteristics.ope

Antimicrobial Effects against Oral Pathogens and Cytotoxicity of Glycyrrhiza uralensis Extract

We aimed to evaluate the antimicrobial effects ofGlycyrrhiza uralensisextract onStreptococcus mutansandCandida albicansand its biocompatibility for dental applications. The antimicrobial activity of theG. uralensisextracts at concentrations of 50, 100, 150, and 200 mu g/mL was assessed using agar disk diffusion tests, counting the total number of colony-forming units (CFUs), spectrophotometric growth inhibitory assays, and microbial morphology observations using scanning electron microscopy (SEM; Merin, Carl Zeiss, Oberkochen, Germany). We measured the polyphenol and flavonoid contents ofG. uralensisextracts using ultraviolet-visible spectrometry and the cytotoxicity of these extracts using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. We identified thatG. uralensisextracts had significant antimicrobial effects againstS. mutansandC. albicans. The optical density of the experimental groups significantly decreased compared with that of the control group. SEM images revealed that theG. uralensisextract affected the morphology and density ofS. mutansandC. albicans. The extract concentration of flavonoids, but not polyphenols, increased with increasing concentrations of theG. uralensisextract. Furthermore, cell viabilities were more than 70% forG. uralensisextracts with concentrations of 50 and 100 mu g/mL. Naturally derivedG. uralensisis biocompatible and exhibits an excellent antimicrobial effect against oral pathogens such asS. mutansandC. albicans. Thus,G. uralensisextracts can be used for the development of oral products that treat and prevent oral diseases.ope

Biocompatibility and Antimicrobial Activity of Reynoutria elliptica Extract for Dental Application

This study was conducted to determine whether nature-derivedReynoutria ellipticaextracts exhibit biocompatibility and antimicrobial effects against oral pathogens such asStreptococcus mutansandCandida albicans. Fine particles ofReynoutria ellipticaextract were used to probe for biocompatibility and antimicrobial activity toward these pathogens,and results were evaluated with an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, spectrophotometric growth inhibitory assay, the total number of colony-forming units (CFU), an agar disk diffusion test, and scanning electron microscopy (SEM). In addition, UV/VIS spectroscopy was used to determine the levels of flavonoid and polyphenol in experimental solutions. Several experimental groups showed cell viability higher than 70%, and the antimicrobial activity toward bothS. mutansandC. albicanswas significantly higher than was that seen for the control group. In CFU and agar disk diffusion tests withC. albicans, increases in the concentration ofReynoutria ellipticaextract led to significantly increased antimicrobial effects. Additionally, SEM results showed thatReynoutria ellipticaextract changed the morphology and density ofS. mutansandC. albicans. The results of this research can be applied to the use ofReynoutria ellipticaextracts for the development of oral products that are biologically friendly and can control oral diseases such as dental caries and candida-associated denture stomatitis.ope

적응적 임상시험에 대한 고찰과 한국에서의 적응적 임상시험 적용과 발전을 위한 제안

학위논문 (석사)-- 서울대학교 보건대학원 : 보건대학원 보건학과 보건학 전공, 2016. 2. 조성일.신약 개발에 대한 관심과 연구현황은 한국뿐만 아니라 전 세계적으로 의학 및 보건학 분야에서 매우 두드러지게 나타나고 있다. 따라서 보다 효과적인 임상시험을 통하여 시험하고자 하는 임상시험약 또는 치료법의 안전성(safety)과 유효성(efficacy)을 보다 적은 비용과 짧은 시간 내에 입증하여 성공적인 임상시험(clinical trial)으로 이끌어 내기 위하여 통계적, 규제적, 윤리적인 측면에서 많은 연구자들이 노력하고 있다. 지난 2000년대 초반에 미국 식품의약국(United States Food and Drug Administration, 이하 FDA)에서는 신약개발에 있어서 제약 업계에서 계획 준비 중인 의약품의 개발을 위하여 도움을 줄 수 있는 임상시험의 최상경로계획(Critical Path Initiative, 이하 CPI)을 총 76가지의 초기 프로젝트로 총 6개의 광범위한 주제를 개요 서술한 임상시험의 최상경로기회 목록(Critical Path Opportunities List)을 발표하였다. 이 발표로 인하여 적응적 임상시험(adaptive clinical trial) 또는 유연한 임상시험(flexible clinical trial)이 제안되었는데, 이는 임상시험의 중간 분석을 통하여 획득 되어진 정보를 바탕으로 그 임상시험의 한 가지 이상의 명시 된 방면의 수정을 가능하게 하는 새로운 방법으로 신약개발의 성공 확률을 증가시킬 뿐만 아니라, 신약 개발의 시간을 감소시킨다고 주장하였다. 이후 이러한 적응적 임상시험에 대한 연구는 활발하게 진행되고 있는 실정이다. 본 연구에서는 적응적 임상시험의 현 상황과 이해를 돕기 위하여 적응적 임상시험의 선행연구의 현황과 적응적 임상시험의 특징과 종류에 대하여 설명하였다. 이에 더 나아가 미국 및 유럽연합 국가에서 설계한 적응적 임상시험의 총 4가지 사례에 대하여 체계적인 고찰을 실시하였다. 총 4가지 사례를 통하여 적응적 임상시험의 장점과 단점/한계점을 결과적으로 도출하였고, 장점으로는 적응적 임상시험은 기존의 전통적인 임상시험(traditional clinical trial)과 비교/대조하여 임상시험에 소요되는 시간을 단축시키고 경제적인 비용을 줄이며 보다 적은 표본 크기(sample size)에 더 높은 검정력(power)으로 더 나은 연구 결과를 제시하는 데에 큰 의의를 두었다. 하지만 적응적 임상시험의 단점/한계점으로는 적응적 임상시험 사용에 있어서 기존의 임상시험 보다 통계학적, 규제적 및 기술적인 발전과 연구가 더 필요함을 제안하였고, 유효성(efficacy) 결과 도출 및 비효과적인 약물군 및 치료군에 대한 연구의 제한이 있었으며 일반화에 대한 오류 가능성을 배제할 수 없었다. 그리고 본 논문에서는 이러한 결과를 바탕으로 한국에서 적응적 임상시험 사용 시에 어떻게 적절하고 체계적으로 적용해야함을 함께 제시하였다.제1장 서론 1 제1절 도입 1 1.적응적 임상시험에 대한 정의 1 2.적응적 임상시험에 대한 연구현황 2 3.적응적 임상시험에 대한 연구 필요성 4 4.적응적 임상시험에 대한 연구 목적 5 5.논문의 구성 6 제2절 배경 6 1.적응적 임상시험의 특징 6 2.적응적 임상시험의 선행연구 7 제3절 연구방법 11 1.연구의 요약 11 2.연구 디자인 내용 12 3.연구 가설의 설정 13 제2장 본론 14 제1절 적응적 임상시험의 분류와 종류 14 1.적응적 임상시험의 의미상 분류 14 2.적응적 임상시험의 절차상 분류 15 3.적응적 임상시험의 종류 16 제2절 적응적 임상시험에 대한 고찰 19 1.적응적 임상시험 사례 19 2.적응적 임상시험 사례들의 고찰 19 3.적응적 임상시험 사례들의 고찰 결과 분석 35 제3장 결론 40 제1절 연구의 요약 40 제2절 연구의의 40 제3절 한계점 41 제4절 향후 연구 방향 41 참고 문헌 43 Abstract 53Maste

Comparison between division of health science and dental hygiene in Korea

Objectives : This review suggests prospect of educational institutions through research on the establishment trend of Korean dental hygiene programs by comparison with health science programs, analysis based on location and year. Methods : For the research, 78 dental hygiene programs, 11 dental colleges, 144 nursing programs, 41 medicine programs, 38 radiology programs, 49 optometry programs, 39 biomedical laboratory science programs, 65 physical therapy programs, 48 occupational therapy programs were analyzed using SPSS 12.0v. The result is as follows. Results : Establishment trend of dentistry-related programs and dental hygiene programs is twice as high as nursing programs and medicine-related programs. Number of 3-years dental hygiene programs is twice as high as 4-years dental hygiene programs. Entrance quota of 3-years dental hygiene programs is four time higher than 4-years programs. On regional basis, number of dental hygiene programs is the highest in Gyeonggi-do by 9 while it is the lowest in Incheon-si and Jeju-do by 1. Number of students in dental hygiene programs is the highest in Gyeonggi-do by 2,514. Establishment of dental hygiene programs showed the biggest increasing trend in Gyeonggi-do and Jeju-do from 1995 to 1999; and in Gangwon-do, Chungcheongbuk-do, Chungcheongnam-do, Gyeongsangbuk-do, Gyeongsangnam-do, Jeollabuk-do, Jeollanam-do from 2005 to 2010. Conclusions : Assurance of legal rights in the workplace and improvement of educational environment should take prudence over establishment of dental hygiene programs in order to develop professionalism among students in dental hygiene.ope

Biocompatibility Evaluation of Dental Luting Cements Using Cytokine Released from Human Oral Fibroblasts and Keratinocytes

Dental luting cements are commonly used in dentistry for cementation of prosthetic restoration. Many previous studies focused on the measurement of the cell viability as the method of cytotoxicity evaluation during biocompatibility study for the material. In this study, the biocompatibility of various dental luting cements were evaluated using the new method of cytokine release measurement in order to better simulate inflammatory reactions in animal or clinical model using two different oral cells; immortalized human gingival fibroblast and immortalized human oral keratinocytes. Cells were exposed to extractions of various commercially available dental luting cements for different durations. Cytokines of IL-1α and IL-8 were measured from the supernatants of the cells and the results were then compared to the conventional MTT viability test. The result from the conventional cell viability study showed a relatively simple and straight forward indication that only one of the dental luting cements tested in this study was cytotoxic with increasing duration of exposure for both cells. Meanwhile, the result from the cytokine measurement study was much more complex at the time point they were measured, type of cells used for the study and the type of cytokines measured, all of which influenced the interpretation of the results. Hence, the better understanding of the cytokine release would be required for the application in biocompatibility evaluation.ope

The Research of Classification Systems for Dental Materials of Korea Food and Drug Administration and Other Countries

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Effect of Microwave Treatment on the Physical Properties of Polyvinyl Siloxane Impression Materials

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Enamel Demineralization Resistance and Remineralization by Various Fluoride-Releasing Dental Restorative Materials

The aim of this study is to investigate the resistance of various fluoride-releasing restorative materials against the demineralization and remineralization of enamel surfaces, including those that have been recently introduced to the market. Three different fluoride-releasing restorative materials were considered: glass ionomer (FI), resin-modified glass ionomer (RL), and an alkasite restorative material (CN). The acid neutralization ability was investigated using pH measurement, and the concentrations of released fluoride and calcium ions were measured. Finally, the demineralization resistance and remineralization effects of enamel were observed using a microhardness tester and SEM. CN showed an initial substantial increase in pH followed by a steady increase, with values higher than those of the other groups (p < 0.05). All three groups released fluoride ions, and the CN group released more calcium ions than the other groups (p < 0.05). In the acid resistance test, from the microhardness and SEM images, the CN group showed effective resistance to demineralization. In the remineralization test, the microhardness results showed that the FI and CN groups recovered the microhardness from the values of the demineralized enamel surface (p < 0.05). This was confirmed by the SEM images from remineralization tests; the CN group showed a recovered demineralized surface when immersed in artificial saliva for 7 days. In conclusion, alkasite restorative material can be an effective material when used in cariogenic environments.ope

Simplified Model을 이용한 캐나다 Horn River 분지의 셰일가스 생산량 예측 및 표준곡선 추정

Decline curve anaanalysis is by far the most widely used tool for assessing oil and gas reserves from rate performance. To estimate production rate, the best curve fitting of past production performance is done in boundary dominated flow. And also decline exponent, b, could not exceed 1. The decline exponent of low permeability reservoir can exceed 1. Dual porosity and transition flow of low permeability could cause the reserves overestimation. To compensate the overestimation, Khaled(2006) suggested Simplified Model that combine hyperbolic case and exponential case. He introduced the transition point from hyperbolic case to exponential case. Fetkovich`s type curve is for estimating reservoir property, decline exponent, and reserves by matching between production history and type curve. For drawing type curve of shale gas field, Decline envelopes method is probabilistic forecast method easily. In this work, Simplified Model has been used to forecasting production rate, EUR and production type curve of shale gas production in Horn river basin, Canada. As results of this study, production rate and EUR of Simplified Model is more appropriate than Arps empirical equation. Matching between Simplified Model and production history is better than Arps empirical equation, either early time or late time. Production type curve for Simplified Model can represent production decline trend of production history.1. 서 론 2. 생산 감퇴곡선 및 표준곡선 추정 기법 2.1 Arps 경험식 2.2 Simplified Model을 이용한 감퇴곡선 분석 2.3 표준곡선 추정 기법 3. 생산 감퇴곡선 분석법을 이용한 생산량 예측 3.1 연구 대상 지역 3.2 Arps 경험식에 의한 생산량 예측 3.3 Simplified Model에 의한 생산량 예측 3.4 Simplified Model의 생산량 검증 4. Decline Envelopes 방법을 이용한 표준곡선 추정 4.1 표준곡선 추정 4.2 표준곡선을 통한 궁극가채량 예측 4.2.1 생산정별 궁극가채량 예측 4.2.2 표준곡선을 이용한 궁극가채량 예측 5. 결론 감사의 글 참고문