Physicomechanical properties of strontium and fluoride modified biodentineTM

Objectives: To investigate the effect of bioactive glass addition on the physicomechanical properties of BiodentineTM. The study compares the setting time, compressive strength and radiopacity of BiodentineTM modified by three different compositions of bioactive glassesDesign: This was an exploratory lab based quasi-experimental studySetting: The study was conducted in the laboratory at Queen Mary, University of London Dental Physical Sciences Unit.Materials and methods: Dental cements based on BiodentineTM and its modifications were used in the study. Original unmodified BiodentineTM cement was coded BO. Three bioactive glasses based on high fluoride (Q), high strontium (I) and high fluoride + strontium (H)were synthesized and 0.07g of each of the bioactive glasses added to BiodentineTM powder to yield 3 additional types of cements which were coded BQ, BI and BH respectively. A set mass of each cement type was prepared by adding 5 drops of the liquid supplied with BiodentineTM to the powders and triturating for 30 seconds in a 4000rpm electric amalgamator. These cements were subjected to setting time determination, compressive strength testing and radiopacity testing according to ISO 9917-1: 2007.Setting time and compressive strength were statistically analysed using T-test at 95% confidence level at a significance level of 0.05.Results: Bioactive glass addition resulted in initial setting times of11.31+0.18, 12:22+ 0.11, 11:59+ 0.15 and 13:35+0.23 minutes for BO, BQ, BI and BH respectively. The increased setting time of BQ and BH were statistically significant. Student t-test analysis of compressive strength demonstrated statistically higher 14 day compressive strengths for BI (p=0.036) and BH (p=0004). BH cement had the highest grey scale value equivalent to 2.9mm of aluminium, which was consistent with the best radiopacity among the 4 BiodentineTM based cements.Conclusion: Bioactive glass addition to BiodentineTM improved the radiographic detectability and compressive strength of the cement. This is important since current use of BiodentineTM is limited owing to inadequate strength and detection on radiographs. However, further studies are needed to explore alternative modifications that could shorten the setting time of this cement

Selection of impression materials and techniques employed by dentists in Kenya

Objectives: The aim of the study was to determine the preferred impression material and impression recording technique employed by the dentists in Kenya for specific clinical procedures.Design: A descriptive cross sectional study.Setting: Dental clinics/institutions within Kenya.Participants: Dentists registered by the Medical Practitioners and Dentists Board as at 2015.Methods: A sample n=322 was randomly selected among the 1000 dentists registered in 2015. Data was collected using a pre-tested self-administered questionnaire that was distributed via online web-based survey monkey softwareand off-line by data collection assistants. Data was analysed using SPSS version 20 and Microsoft Excel 2013. Results were presented in tables, pie and bar charts.Results: Ninety seven dentists (30.1%) returned the questionnaires, 57 (58.8%) completed the hard copy version while 40 (41.2%) responded via the on-line tool. Majority of the respondents were males 52 (53.6%), 44 (45.4%) females while one dentist (1%) did not respond. Nearly half of the dentists 44 (46.4%) had 0-5 years clinical experience and a sizeable number 72 (74.2%) were general practitioners. Majority 56 (57.7%) considered availability, cost, ease of use and degree of accuracy in selecting impression materials (IM’s). The most commonly used (IM) was alginate whereas the least applied were polysulphide and vinyl siloxanether. Alginate was used in primary and final impressions of all procedures except border moulding, mostly in study model 88 (90.7%) and least in complete denture final impression 4 (4.1%). Addition and condensation cured silicones were preferred for fixed restoration impressions with majority 40 (41.1%) using single mix impression technique. One dentist used digital impression recording technique.Conclusion: Selection of (IM’s) is influenced by availability, cost, ease of use and degree of accuracy. Alginate and silicone impression materials were most utilised. The single mix impression technique was more popular while digital impression technique is yet to be widely embraced by dentists in Kenya

Undocumented Immigrants in the U.S. Health Care System: A Study of Latinos in Oregon

Health care and immigration in the United States are complex and controversial topics. Undocumented immigrants have to overcome numerous barriers in order to gain access to health care services. This study examines the personal experiences of undocumented immigrants in Oregon and how they sought out care and overcame these barriers. Seven in-depth interviews were conducted and then analyzed for thematic content. Results supported previous research that identified five types of barriers undocumented immigrants commonly face; structural, nonstructural, systemic, cultural and linguistic. Over time improvements have been made to help make care more accessible. For example, there are an increasing number of interpreters and/or bilingual and bicultural staff and state programs have been designed to help decrease the number of uninsured. However, systemic changes, along with increased health education and more culturally competent care, will be critical components to address, in order to improve health care for undocumented immigrants in the United States

Comparative Analysis of CD57 and Proliferating Cell Nuclear Antigen (PCNA) Expression in Oral Squamous Cell Carcinoma: An Immunohistochemical study

BACKGROUND: Natural killer cells play an important role in the innate and adaptive immune system. The immune defense against tumour cells is mainly mediated by the natural killer cells. Cluster of differentiation 57 is a 110-kd glycoprotein, typically expressed by the natural killer cells, attack the cancer cells and inhibit the tumour development. Proliferating cell nuclear antigen (PCNA) is a 36 kd auxiliary protein for DNA polymerase delta, located on chromosome 20p12 correlates with the cell proliferation and DNA synthesis. This PCNA protein varies during cell cycle and accumulates in late G and S phase of the cell cycle. PCNA is essential component of the DNA replication, DNA recombination and repair. AIMS AND OBJECTIVE: To compare and correlate the expression of CD57 and PCNA in different grades of oral squamous cell carcinoma by immunohistochemistry. MATERIALS AND METHODS: Previously histopathologically confirmed 30 samples of different grades of oral squamous cell carcinomas and 10 samples of normal mucosa were included in this retrospective study. The histopathological sections were examined immunohistochemically for CD57 and PCNA expression. The statistical analysis was done by Anova (Post hoc) followed by Dunnet t-test and correlation between the markers was done by Pearson correlation test. RESULTS: The CD57 expression in oral squamous cell carcinoma was found to be higher in well differentiated squamous cell carcinoma and lower in poorly differentiated squamous cell carcinoma whereas expression of PCNA was found to be lower in well differentiated squamous cell carcinoma and higher in poorly differentiated squamous cell carcinoma. CONCLUSION: CD57 expression was found to be decreasing from well differentiated squamous cell carcinoma to poorly differentiated squamous cell carcinoma. On the other hand, proliferative activity was found to be increasing from well differentiated squamous cell carcinoma to poorly differentiated squamous cell carcinoma. Therefore, the combination of CD57 and PCNA biomarkers appears to be good indicators of the immune status of the patient and the aggressiveness of the lesion

THE IMPORTANCE OF KNOWLEDGE TRANSFER FOR FIRM BEHAVIOR/ A importância da transferência de conhecimento para o comportamento da empresa

Abstract: Conscious management of the transfer of knowledge in the firm is vital for the firm’s situation and development of competitiveness. In this paper, we examine the knowledge transfer process within a traditional firm, to see how the transfer process depend on contextual factors such as characteristics of senders and receivers. Empirical analysis are based on survey data, containing variables on communication, competence, innovation and culture. The survey data were collected from group leaders responsible for different production function over a five-year period, with respondents answering the same questionnaire repeatedly at approximately 12-month intervals. Survey respondents were organized in two groups based on their position in the firms production, either assembly line functions or support functions. The analysis is based on a total of 266 questionnaires. A t-test for equality of means where done in order to test for any differences in knowledge transfer within the different groups. The results show significant differences in the knowledge transfer process between workers in different functions in the firm. Level of formal education and structural configuration can explain some of the differences.Keywords: Knowledge transfer, communication, competence, innovation, culture Resumo: A gestão consciente da transferência de conhecimento na empresa é vital para o seu desempenho e o desenvolvimento da competitividade. Neste artigo, se examina o processo de transferência de conhecimento dentro de uma empresa tradicional, para analisar como o processo de transferência depende de fatores contextuais, como características de emissores e receptores. A análise empírica foi baseada em dados de pesquisa, contendo variáveis sobre comunicação, competência, inovação e cultura. Os dados foram coletados de líderes de grupo ao longo de um período de cinco anos. Os respondentes da pesquisa foram organizados em dois grupos com base em sua posição na produção da empresa, sejam funções de linha de montagem ou funções de suporte. Os entrevistados responderam ao mesmo questionário repetidamente em intervalos de aproximadamente 12 meses. A análise foi baseada em um total de 266 questionários. Um teste t para igualdade de médias foi feito a fim de testar quaisquer diferenças na transferência de conhecimento dentro dos diferentes grupos. Os resultados mostram diferenças significativas no processo de transferência de conhecimento entre trabalhadores em diferentes funções na firma. O nível de educação formal e a configuração estrutural podem explicar algumas das diferenças.Palavras-chave: Transferência de conhecimento, comunicação, competência, inovação, cultura. A gestão consciente da transferência de conhecimento na empresa é vital para o seu desempenho e o desenvolvimento da competitividade. Neste artigo, se examina o processo de transferência de conhecimento dentro de uma empresa tradicional, para analisar como o processo de transferência depende de fatores contextuais, como características de emissores e receptores. A análise empírica foi baseada em dados de pesquisa, contendo variáveis sobre comunicação, competência, inovação e cultura. Os dados foram coletados de líderes de grupo ao longo de um período de cinco anos. Os respondentes da pesquisa foram organizados em dois grupos com base em sua posição na produção da empresa, sejam funções de linha de montagem ou funções de suporte. Os entrevistados responderam ao mesmo questionário repetidamente em intervalos de aproximadamente 12 meses. A análise foi baseada em um total de 266 questionários. Um teste t para igualdade de médias foi feito a fim de testar quaisquer diferenças na transferência de conhecimento dentro dos diferentes grupos. Os resultados mostram diferenças significativas no processo de transferência de conhecimento entre trabalhadores em diferentes funções na firma. O nível de educação formal e a configuração estrutural podem explicar algumas das diferenças

Sol-gel synthesis of lithium doped mesoporous bioactive glass nanoparticles and tricalcium silicate for restorative dentistry: Comparative investigation of physico-chemical structure, antibacterial susceptibility and biocompatibility

Introduction: The sol-gel method for production of mesoporous bioactive glass nanoparticles (MBGNs) has been adapted to synthesize tricalcium silicate (TCS) particles which, when formulated with other additives, form the gold standard for dentine-pulp complex regeneration. Comparison of TCS and MBGNs obtained by sol-gel method is critical considering the results of the first ever clinical trials of sol-gel BAG as pulpotomy materials in children. Moreover, although lithium (Li) based glass ceramics have been long used as dental prostheses materials, doping of Li ion into MBGNs for targeted dental applications is yet to be investigated. The fact that lithium chloride benefits pulp regeneration in vitro also makes this a worthwhile undertaking. Therefore, this study aimed to synthesize TCS and MBGNs doped with Li by sol-gel method, and perform comparative characterizations of the obtained particles.Methods: TCS particles and MBGNs containing 0%, 5%, 10% and 20% Li were synthesized and particle morphology and chemical structure determined. Powder concentrations of 15mg/10 mL were incubated in artificial saliva (AS), Hank’s balanced saline solution (HBSS) and simulated body fluid (SBF), at 37°C for 28 days and pH evolution and apatite formation, monitored. Bactericidal effects against S. aureus and E. coli, as well as possible cytotoxicity against MG63 cells were also evaluated through turbidity measurements.Results: MBGNs were confirmed to be mesoporous spheres ranging in size from 123 nm to 194 nm, while TCS formed irregular nano-structured agglomerates whose size was generally larger and variable. From ICP-OES data, extremely low Li ion incorporation into MBGNs was detected. All particles had an alkalinizing effect on all immersion media, but TCS elevated pH the most. SBF resulted in apatite formation for all particle types as early as 3 days, but TCS appears to be the only particle to form apatite in AS at a similar period. Although all particles had an effect on both bacteria, this was pronounced for undoped MBGNs. Whereas all particles are biocompatible, MBGNs showed better antimicrobial properties while TCS particles were associated with greater bioactivity.Conclusion: Synergizing these effects in dental biomaterials may be a worthwhile undertaking and realistic data on bioactive compounds targeting dental application may be obtained by varying the immersion media

Microearthquake activity adjacent to the Rocklin pluton near Auburn, California

The occurrence of the Oroville earthquake (M_L = 5.7) of August 1, 1975 heightened interest in the seismotectonics of the Sierra foothills region and particularly the Foothills fault system. Clark (1960) recognized the Foothills fault system as being a major structural feature of the western Sierra Nevada. An 11-week reconnalssance microearthquake study was conducted by Woodward-Clyde Consultants (WCC) for the U.S. Bureau of Reclamation (USBR) to assess the seismic activity of the Sierra foothills 75 km S-SE of Oroville near Auburn, California. Microearthquake activity was detected in the Rocklin-Auburn region with eight events recorded during July 1 to July 24 and seven events during August 15 to October 8, 1976 (see Figure 1). The mobile seismic array consisted of eight Sprengnether MEQ-800 portable seismographs with Mark Products L-4C vertical seismometers. Data recordings were normally 48 hours in length, with a record speed of 1 mm/sec

Understanding earthquake hazards in southern California - the "LARSE" project - working toward a safer future for Los Angeles

The Los Angeles region is underlain by a network of active faults, including many that are deep and do not break the Earth’s surface. These hidden faults include the previously unknown one responsible for the devastating January 1994 Northridge earthquake, the costliest quake in U.S. history. So that structures can be built or strengthened to withstand the quakes that are certain in the future, the Los Angeles Region Seismic Experiment (LARSE) is locating hidden earthquake hazards beneath the region to help scientists determine where the strongest shaking will occur