In vitro cytotoxicity and in vivo-biocompatibility of contemporary resin-modified glass-ionomer cements

Objectives. To evaluate the effects of current resin-modified glass-ionomer cements (RMGICs) applied on culture of cells or implanted into subcutaneous tissue of rats.Methods. Experiment 1 - Thirty round-shaped samples of every RMGICs: Rely X Luting Cement (RL), Vitremer (VM), and Vitrebond (VB) were placed into wells with 1.1 mL of culture medium (DMEM), and incubated for 24,48 or 72 h. The extracts from every sample were applied on the MDPC-23 cells. Fresh DMEM was used as control group. The MTT assay was carried out for mitochondrial respiration. Experiment 2 - Fifty-four polyethylene tubes filled with the experimental materials were implanted into the dorsal subcutaneous tissue of rats. At 7, 30, and 90 days the animals were killed and the biopsies were processed for histological evaluation.Results. Experiment 1 - Both time of elution and material significantly influenced cell respiratory activity. in general, the extracts obtained at 24 h were less cytotoxic than 48 and 72 h incubation. The cytotoxic effect of VM and RL were not statistically different (P < 0.05) for the 24-hour period. VB showed the highest cytotoxic effect. Experiment 2 - All RMGICs elicited at 7 days a moderate to intense inflammatory reaction which decreased over time. However, connective healing occurred for most of samples at 90-day evaluation.Significance. Glass-ionomer cements may cause noticeable inflammatory response when in direct contact to connective tissue. The toxic effects of this kind of soluble material depend on the amount of components released in the aqueous environment. (C) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Response of human dental pulp capped with MTA and calcium hydroxide powder

Objectives: To compare the response of human dental pulp capped with a mineral trioxide aggregate (MTA) and Ca(OH) 2 powder. Methods and Material: Pulp exposures were performed on the occlusal floor of 40 permanent premolars. The pulp was then capped with either Ca(OH) 2 powder (CH) or MTA and restored with resin composite. After 30 days (groups CH30 and MTA30) and 60 days (groups CH60 and MTA60), the teeth were extracted and processed for HE and categorized in a histological score system. The data were subjected to Kruskal-Wallis and Conover tests (α=0.05). Results: In regard to dentin bridge formation, CH30 showed a tendency towards superior performance compared to MTA30 (p>0.05), although the products showed comparable results at day 60. In the item Inflammation and General State of the Pulp (p>0.05), CH showed a tendency towards presenting a higher inflammatory response. In the item Other Pulpal Findings, MTA and Ca(OH) 2 showed equal and excellent performance after 30 and 60 days (p>0.05). Conclusion: After 30 days, Ca(OH) 2 powder covered with calcium hydroxide cement showed faster hard tissue bridge formation compared to MTA. After 60 days, Ca(OH) 2 powder or MTA materials showed a similar and excellent histological response with the formation of a hard tissue bridge in almost all cases with low inflammatory infiltrate. © Operative Dentistry, 2008.

Com engenho e arte: a construção da escrita significativa por crianças de 3ª e 4ª séries

Pós-graduação em Educação - IBRC

Abordagens dos Direitos Reprodutivos em Materiais Didáticos para a Formação Continuada de Educadoras(es): uma análise a partir dos editais da SECAD

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O professor alfabetizador: sua formação, o programa Letra e vida e as lacunas conteudísticas

Pós-graduação em Linguística e Língua Portuguesa - FCLAR

Da leitura à literatura ao letramento literário: prática docente em foco

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Disentangling the influences of habitat structure and limnological predictors on stream fish communities of a coastal basin, southeastern Brazil

Em ambientes de riacho, fatores relacionados à estrutura dos habitats e limnologia interagem regulando os padrões de transferência de energia e matéria, afetando a composição da comunidade de peixes. Em bacias costeiras do sudeste do Brasil as características limnológicas e estrutura dos habitats diferem entre riachos de águas claras e pretas. Os primeiros são compostos por uma variedade de tipos de substrato, possuem velocidades de corrente mais elevadas e baixa condutividade, enquanto os últimos apresentam substrato arenoso, baixas velocidades de corrente e águas escuras e ácidas. Neste trabalho analisamos a importância relativa da estrutura dos habitats e das variáveis limnológicas como preditores dos padrões de composição em comunidades de peixes de riachos. Oito riachos de primeira a terceira ordem foram amostrados na planície costeira da bacia do rio Itanhaém. Capturamos 34 espécies e verificamos que a composição das comunidades foi influenciada por fatores estruturais e limnológicos, sendo os primeiros mais importantes. Uma fração de variação que não pode ser totalmente decomposta, deve-se à influência conjunta da limnologia e estrutura dos habitats. Algumas das espécies restritas aos riachos de águas pretas provavelmente apresentam adaptações fisiológicas e comportamentais para lidar com os baixos níveis de pH. Quando foram examinados somente os riachos de águas claras, toda a variação explicada na composição da comunidade de peixes foi atribuída aos fatores estruturais, devido a preferências específicas por diferentes características de hábitats.

Free radical entrapment and crystallinity of resin composites after accelerated aging as a function of the expiration date

This study evaluated the spin concentration and the crystallinity in different classifications of dental composites as a function of the material condition (new, aged and expired). Specimens were obtained according to the factors: composites: Filtek P60, Filtek Z250, Filtek Z350XT, and Filtek Silorane; and material conditions: new, aged, and expired. The syringe composites underwent an accelerated aging protocol (Arrhenius model). The magnetic properties of the composites were characterized using Electron Paramagnetic Resonance (EPR) and the concentration of spins (number of spins/mass) was calculated. The crystallinity of the composites tested was characterized with X-ray diffraction (XRD). Filtek P60 and Filtek Z250 presented similarities in terms of spin concentration and crystallinity, irrespective of the material condition. The aging protocol influenced the composite Filmic Z350XT that exhibited a significant increase in the spin concentration. Besides, lower intensity peaks of the organic matrix and amorphous silica were also observed for both aged and expired Filtek Z350XT. Although a significant lower spin concentration was observed for the silorane composite in comparison to that of the methacrylates, a decrease in the relative intensity of peaks of the amorphous region related to the organic components in the diffractograms was observed. The material conditions tested influence the crystallinity and the magnetic properties of the composites evaluated. (C) 2014 Elsevier Ltd. All rights reserved.

Polymerization kinetics and polymerization stress in resin composites after accelerated aging as a function of the expiration date

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Femoral Biomechanic and microtomography from male rats submitted to dietary restricition supplemented with sucrose

Food restriction reduces body weight and influence bone mass and also is correlated with bone mineral density (BMD). Mechanisms have been proposed for the loss of BMD after body weight reduction, including reduced energy intake. Growing 8 wk-old Wistar male rats were randomly divided into Control and Calorie restriction associated with sucrose 30% (CRS). These animals were subjected to intermittent food restriction during 8 weeks and had free access to tap water and sucrose30% in distilled water. The rats were euthanized at the end of week 8, blood collected from abdominal aorta artery, femurs cleaned of adherent soft tissues, scanned using dual energy X-ray absorptiometry, structural and material properties determined by three-point bending testing in the mid-diaphyseal region, bone surface tested in a microhardness tester and microstructure was assessed in a microcomputer tomography. In CRS animals body weight decreased significantly relative to the Control animals. There was a clear option for high-sucrose beverage in CRS animals. No difference was observed in biochemical, densitometric and biomechanical analyzes. Results from micro CT showed only significant difference in connectivity of trabecular bone. It has been suggested that rats submitted to food restriction consumed sugar not because of its inherent palatability, but in order to alter their macronutrient balance and animals need to meet energy demands in high-sucrose.