728 resultados para RU ALLOY


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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Objectives. This study was undertaken to evaluate the shear bond strength of four materials used as aesthetic material bonded to Ni-Cr alloy.Methods. Sixty-eight alloy discs were prepared and divided equally into four groups, and received four treatments for veneering: conventional feldspathic porcelain (Noritake EX-3) and three light-cured prosthodontic composite resins (Artglass, Solidex and Targis). The aesthetic materials were applied after metal structure conditioning in accordance with the manufacturers' recommendations. The specimens were stored in distilled water at 37 degreesC for 7 days. A universal testing machine was used to measure the shear bond strength of the specimens at a cross head speed of 0.5 mm/min. Fractured specimens were examined by using both optical and scanning electron microscope.Results. The analysis of variance and Tukey's test showed that the strongest mean shear bond was obtained with Noritake EX-3 (mean shear bond strength 42.90 +/- 7.82 MPa). For composites, the highest mean shear bond strength was observed for Targis (12.30 +/- 1.57 MPa); followed by Solidex (11.94 +/- 1.04 MPa) and Artglass (10.04 +/- 0.75 MPa). Optical analysis of the fractured surf aces indicated that for Targis and Noritake EX-3 all failures were a mixture of both cohesive and adhesive patterns. As for Artglass and Solidex, the fractures were mainly adhesive in nature.Conclusions. The Solidex system was equivalent to the Targis system in bond strength and exhibited greater strength than the Artglass system. The porcelain fused-to-metal showed considerably higher shear bond strength than the three metal-resin bonding techniques. (C) 2003 Elsevier B.V. Ltd. Ali rights reserved.

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

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

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The present study was designed to analyse the average depth of the microporosity of a nickel-chromium (Ni-Cr) system alloy (Verabond II). The metal surface was subject to one of the following surface treatment: (i) Electrolytic etching in nitric acid 0.5 N at a current density of 250 mA cm(-2) ; (ii) chemical etching with CG-Etch etchant; and (iii) Sandblasting with alumina particles 50 mum. Half of the samples were polished before the surface treatments. The depth of porosity was measured through photomicrographs (500x) with a profilometer, and the data were statistically analysed using an analysis of variance (anova) followed by Tukey's test. The conclusions were (i) Differents surface treatment of the Ni-Cr system alloy lead to different depths of microporosity; (ii) the greatest depth of porosity was observed in non-polished alloy; (iii) the greatest and identical depth of microporosity was observed following electrolytic etching and chemical etching; (iv) the least and identical depth of microporosity was observed with chemical etching and sandblasting with alumina particles 50 mum, and (v) Chemical etching showed an intermediary depth.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)