959 resultados para adhesive disk


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This study evaluated the cytotoxicity of experimental adhesive systems (EASs) on odontoblast-like cells. Paper discs (n=132) were impregnated with 10 μL of each EAS-R1, R2, R3, R4, and R5 (in an ascending order of hydrophilicity), followed by photoactivation. R1 and R2 are nonsolvated hydrophobic blends, R3 represents a simplified etch-and-rinse adhesive system, and R4 and R5 represent simplified self-etch adhesive systems. Discs were immersed in Dulbecco's modified Eagle's medium for 24 h to obtain eluates applied on MDPC-23 cell cultures. No material was applied on discs used as control (R0). Cell viability [3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay], total protein (TP) production, alkaline phosphatase (ALP) activity, type of cell death, and degree of monomer conversion Fourier transform infrared (%DC-FTIR) were evaluated. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α=0.05). Considering R0 (control) as having 100% of cell viability, R1, R2, R3, R4, and R5 reduced the metabolic activity of cells by 36.4, 3.1, 0.2, 21.5, and 65.7%, respectively, but only R1 and R5 differed from R0. Comparing with R0, lower TP production was observed for R1, R4, and R5, while ALP activity decreased for R1 and R5. Necrotic cell death was predominant for all EASs, but only R1, R4, and R5 differed from R0. Only R5 presented a different apoptotic cell death ratio from R0. R1 presented the lowest %DC (ca. 37%), whereas R4 and R5 presented the highest (ca. 56%). In conclusion, R2 and R3 were not toxic to the MDPC-23 cells, suggesting that the degree of hydrophilicity or %DC of the EASs alone were not responsible for their cytopathic effects. © 2013 Wiley Periodicals, Inc.

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Single crystalline SnO micro-disks, synthesized by a carbothermal reduction process, exhibited a nearly 1000-fold increase in resistance upon exposure to 100 ppm of NO2 without addition of catalysts or dopants nor the existence of nano-sized dimensions. Moreover, the SnO displayed a greater than 100-fold selectivity to NO2 over potential interferents including CO, H2 and CH4. The high sensor signal and exceptional selectivity for this novel sensor material are attributed to the existence of a high density of active lone pair electrons on the exposed (0 0 1) planes of the single crystalline SnO disks. This, thereby, identifies new means, not utilizing nano-dimensions, to achieve high gas sensitivity. © 2013 Elsevier B.V. All rights reserved.

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The aim of this study was to evaluate the transdentinal cytotoxicity of experimental adhesive systems (EASs) with different hydrophilicity and dentin saturation solutions on odontoblast-like cells. One hundred 0.4-mm-thick dentin discs were mounted in in vitro pulp chambers and assigned to 10 groups. MDPC-23 cells were seeded onto the pulpal side of the discs, incubated for 48 h. The EASs with increasing hydrophilicity (R1, R2, R3 and R4) were applied to the occlusal side after etching and saturation of etched dentin with water or ethanol. R0 (no adhesive) served as controls. R1 is a non-solvated hydrophobic blend, R2 is similar to a simplified etch-and-rinse adhesive system and R3 and R4 are similar to self-etching adhesives. After 24 h, cell metabolism was evaluated by MTT assay (n = 8 discs) and cell morphology was examined by SEM (n = 2 discs). Type of cell death was identified by flow cytometry and the degree of monomer conversion (%DC) was determined by infrared spectroscopy (FTIR) after 10 s or 20 s of photoactivation. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests (α = 0.05). Dentin saturation with ethanol resulted in higher necrotic cell death ratios for R2, R3 and R4 compared with water saturation, although R2 and R3 induced higher SDH production. Photoactivation for 20 s significantly improved the %DC of all EASs compared with 10 s. A significant positive correlation was observed between the degree of hydrophilicity and %DC. In conclusion, except for R1, dentin saturation with ethanol increased the cytotoxicity of EASs, as expressed by the induction of necrotic cell death. © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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Pós-graduação em Ciências Odontológicas - FOAR

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Pós-graduação em Engenharia Mecânica - FEIS

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classifed according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specifc acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and defciencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplifed ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

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A superfície oclusal excessivamente desgastada pode resultar em desarmonia oclusal e prejuízo à estética e função. Como abordagem terapêutica, coroas unitárias convencionais têm sido propostas, porém este tipo de tratamento é complexo, altamente invasivo e caro. Este relato de caso descreve os resultados clínicos de um tratamento alternativo minimamente invasivo baseado em restaurações adesivas diretas retidas por pinos. Uma paciente de 64 anos apresentando dentição severamente desgastada, problemas mastigatórios relacionados às ausências dentárias e hipersensibilidade dental generalizada foi encaminhada para tratamento. O adequado plano de tratamento baseado no enceramento diagnóstico foi utilizado para guiar a reconstrução dos dentes anteriores superiores com resina composta direta sobre pinos dentinários auto-rosqueáveis. Como os dentes inferiores remanescentes eram extremamente desgastados, uma sobre-dentadura dento-suportada foi instalada. Uma placa estabilizadora também foi utilizada de modo a proteger as restaurações. Este tratamento constitui uma alternativa mais acessível de reabilitação de boca total com resultados estéticos e funcionais positivos após 1,5 anos de acompanhamento.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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OBJETIVO: Avaliar in vitro a resistência ao cisalhamento de compósitos autopolimerizáveis (Concise e Alpha Plast) e fotopolimerizáveis (Transbond XT e Natural Ortho) utilizados na colagem de braquetes metálicos da marca Morelli, analisando o índice de adesivo remanescente (ARI) e da integridade da superfície do esmalte por meio de microscopia eletrônica de varredura (MEV). MÉTODOS: foram utilizados 40 pré-molares humanos extraídos. As raízes dos dentes foram incluídas em gesso-pedra especial, no interior de tubos de PVC usados para a confecção dos corpos de prova. Esses corpos de prova foram divididos em quatro grupos: grupo G1, braquetes associados ao compósito Concise; grupo G2, braquetes associados ao compósito Alpha Plast; grupo G3, braquetes associados ao compósito Transbond XT; e grupo G4, braquetes associados ao compósito Natural Ortho. Os grupos foram submetidos ao teste de cisalhamento em máquina universal de ensaios, a uma velocidade de 0,5mm por minuto. RESULTADOS: houve diferença estatística entre os grupos G3 e G4, sendo os valores de G4 superiores; no entanto, não foram encontradas diferenças estatisticamente significativas entre os grupos G1, G2 e G3 e G1, G2 e G4. Na análise do ARI não foram encontradas diferenças estatísticas entre os grupos, predominando escores baixos. De acordo com a análise da MEV, constatou-se o rompimento dos compósitos e a integridade do esmalte entre os grupos. CONCLUSÃO: a resistência ao cisalhamento foi satisfatória e semelhante entre os compósitos utilizados, sendo que a resina Natural Ortho apresentou-se superior à Transbond XT.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)