286 resultados para Hidrogênio difusível


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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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Pós-graduação em Química - IQ

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Pós-graduação em Química - IQ

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The aim of this study was to evaluate and compare the roughness and superficial morphology of enamel and a composite restorative resin after different bleaching techniques application. Material and Methods: Bovine incisors were selected and standardized cavities were prepared on the buccal surface, which were restored with composite resin. The teeth were distributed according to the following treatments: G1- bleaching with 10% carbamide peroxide (CP); G2 - bleaching with 38% hydrogen peroxide (HP); and G3 - bleaching with 38% of HP associated to light irradiation. For G1, the bleaching gel was applied for 8 hours daily during 21 days. For G2 and G3, 3 sessions were performed, consisting of 3 applications of 15 minutes each, with 7 days of intervals between the sessions. For G3, the LED (470nm) light was used to activate the bleaching agent for 6 minutes. The surface of enamel and composite resin were evaluated before and after the bleaching procedures using a roughness tester and an atomic force microscope. Results: The results showed significant differences in surface roughness of enamel after bleaching only for G1 (Wilcoxon, p<0.05). For composite resin, neither group showed a statistical difference compared to control (Mann-Whitney, p>0.05). Conclusion: It was concluded that the increase in the roughness of enamel occurred only after bleaching therapy using a gel with 10% of CP. The bleaching procedures evaluated in this investigation did not increase the roughness or cause changes in the superficial morphology of the composite resin.

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The increasing importance of aesthetic in the Dentistry for the patients and the consumers brought a constant rise in the number of products and procedures to facilitate the confection of the dental bleaching. Concomitantly, thone was a sudden increase in the number of research and publications, in vitro and in vivo, about its possible adverse reactions. Through literature revision this study aims to verify the possible morphologic alterations of the submitted enamel and dentine with different bleaching agents making critical analysis of the results of the current research with relation to the study of the microhardness and superficial roughness.

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The esthetics of the teeth is not a privilege of our days, because concerns in that effect have been reported since 1860. Faced with an endodontically treated tooth that presents any type of color change, professionals can use intracoronary bleaching, which is more conservative attempt to restore the normal color of teeth. Bleaching aims to remove pigments by oxidizing agents and for that, various techniques were developed. Among the risks of tooth whitening the external resorption is the most severe, which occurs when the whitening penetrates through the dentin tubules to the periodontal ligament and initiates an inflammatory response. To prevent external resorption is required to place an intracoronal bleaching barrier. It is important to know the time between the bleaching treatment for restoring procedure for getting a good sealing to prevent microleakage. This study aims to review the literature about the different types of bleaching agents and their risks.

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The increasing interest of patients for a better aesthetic appearance of their smile, associated with the development of new materials and techniques, encouraged by media couverage of this concept of beauty, provided an important evolution of cosmetic dentistry. As the darkness of a single anterior tooth or a group of teeth, in most cases, impairs the appearance of the smile and there is growing appreciation of the less invasive procedures, the technique of tooth bleaching is an important option for aesthetic treatment. To have success in the bleaching treatment, it is important to have knowledge of the origin, nature and composition of the stain. Among the causes of color changes acquired post-eruptive, dental trauma, with or without pulp necrosis, is one of the most commonly encountered etiologies, characterized by a reddish-brown color. Current techniques of bleaching for teeth treated endodontically employ oxidative agent hydrogen peroxide. The objective of this paper is to describe the immediate technique of bleaching non-vital tooth by presenting a clinical case.

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The purpose of this study is to verify the effect of three different types of dentifrices on the superficial microhardness of bovine enamel. Methods: Forty-eight 4x4mm dental fragments were polished and randomly divided into 4 groups: GI, conventional silica-based dentifrice; GII, hydrogen peroxide-based dentifrice; GIII, carbamide peroxide-based dentifrice; and GIV, immersion in artificial saliva. After polished, the specimens received five indentations of 25g static load, for 5 seconds. Subsequently, specimens from groups GI, GII and GIII were immersed in solution containing dentifrice and distilled water, in weight proportion of 1:2, for 15 minutes daily. After this period, fragments were rinsed in tap water and stored in artificial saliva at 37oC. This procedure was repeated for 21 days and then a new analysis of the microhardness was performed. Results and conclusion: The results were submitted to ANOVA and Fisher’s test at 5%. It was concluded that all samples treated with dentifrices showed hardness decrease, being most pronounced in dentifrices containing peroxide.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)