684 resultados para fratura padronizada


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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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Pós-graduação em Odontologia Restauradora - ICT

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The industry generally has sought materials with high mechanical resistance, low density, thermal stability and corrosion resistance. In the aerospace industry, for example, the use of aluminum alloys, such as Al 2024-T351 and Al 7075-T7351, have become essential. However, the use of these materials often do not resulted in a satisfactory performance of the component, since the presence of cracks can cause total rupture of the component, even with a tension below the yield stress of the material, unexpectedly. In this work, these aluminum alloys were analyzed and samples were modeled by the finite element method. Moreover, in the models were applied two different types of cracks, central and edge crack, a vertical force was applied to result in a tension 70% of the yield stress of the material analyzed. Through stress asymptotic distribution in the region near the crack tip were calculated the values of the stress intensity factors for each crack length, after the stress intensity factors characterized were compared graphically with the values of fracture toughness found in the available literature

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This work will address the study of fatigue conditions with constant load in an alloy of aluminum analysis 7475 - T761, so we can better understand the conditions of the aircrafts which contain this alloy in their structures. A literature review, which was discussed the concepts of fracture mechanics, fatigue, aeronautical components, chemical analysis of aluminum alloys, fatigue problems that appears in the aircrafts, metallographic analysis, and testing of optical microscopy tensile, fatigue and microhardness, surface analysis (MEV) study of the chemical composition of the alloy in question, the main causes of crashes, was performed, completing the work, analysis of data from tensile test, hardness and fatigue together with the interpretation of images of optical microscopy and scanning electron was taken. The data indicated the high mechanical strength of the alloy, along with its microstructure indicating elongated grains and high surface contour, which shows such resistance by hindering the movement of dislocations. The grooves are clearly shown in the MEV images as well as the classic with increased fatigue loading and subsequent reduction of the number of cycles to rupture behavior shown in the graphs. Therefore we observed the optimal behavior is supported by the league when subjected to fatigue loadings

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Aluminum alloys have shown great potential for the automotive industry, especially aluminum alloys 6xxx series. This category has good mechanical strength and excellent corrosion resistance, important for the areas of construction and transport. The automotive industry has always shown great interest in the study of fatigue behavior, because structural components are subjected to cyclic and vibration loads, generating cracks and fracturing. The mechanical response depends on the material properties, applications, surface condition and microstructure. In this work was study the fatigue behavior of high cycle of machined bodies (not polished) and the effect of roughness on the fatigue life for three aluminum alloys of 6xxx series: AA6005, AA6351 and AA606, all in the T6 condition . S / N curves were made from fatigue tests in rotating bending (R = -1). The influence of roughness was studied by measuring the roughness of each specimen. Was compare the fatigue behavior of polished specimen and not polished specimens. The fractured surfaces of samples were observed by MEV, and it was observed that most of nucleation sites for fatigue crack is initiated below the surface

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The use of different methods and materials should be considered during the planning of implant-supported prostheses. Complications such as fractures of the acrylic resin base, wear and fracture of teeth can occur frequently, creating the need for careful planning for each patient, which can make the selection of the type of treatment more complex. Thus, this article describes the oral rehabilitation of a completely edentulous patient with bimaxillary fixed implant-supported prosthesis, with complaints on aesthetics, loss of vertical dimension and fracture of acrylic resin teeth of the upper arch. After the restoration of vertical dimension, his dentures were replaced with new bimaxillary implant-supported fixed prostheses, ceramic and acrylic resin were used as veneering material for maxilla and mandible, respectively. At the end of the treatment, the patient received bimaxillary flat occlusal splints to protect the teeth and implants of possible parafunctional habits. The approach for the treatment allowed a quick and effective resolution, with aesthetic and functional outcomes very favorable for the patient.

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Objective: This study evaluated the effects of root canal obturation employing lateral compaction technique and spreader load of 1.5 kg on the incidence of complete (CVRF) or incomplete vertical root fractures (IVRF). Material and Methods: Twenty-seven distal roots of extracted human mandibular molars were used. All root canals were prepared by biomechanical step-back technique and obturated by lateral compaction technique. The prepared roots were distributed into two groups: G1- experimental (n = 17) and G2- control (n = 10). During obturation, load of 1.5 kg was applied to a size # 30 finger spreader. Pre- and post-obturation images of the coronal portion of the roots were captured by inverted digital microscopy and analyzed by one trained examiner. Data were evaluated by Fisher’s test (p < 0.05) using GrapH Pad Prism 5.0. Results: No roots exhibited CVRF. All fractures observed before and after obturation were IVRF or “other defects”. In G2 (control group), there was no increase of IVRF number. Interestingly, G1 presented an increase in the IVRF number to 70.59% in the 12 teeth out of 17 teeth studied. The statistical analysis showed that the mean of IVRF increased significantly in G1 when compared to G2 (p < 0.05). Conclusion: The application of a 1.5 kg spreader load during lateral compaction technique does not produce complete vertical root fractures, but may produce incomplete fractures or “other defects”.

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Introdução: a perda da dimensão vertical de oclusão (DVO) é resultada de um grande desequilíbrio oclusal, onde não apenas a perda dos dentes pode ser o fator responsável, mas também as parafunções, entre elas, o bruxismo. O restabelecimento da relação maxilomandibular é condição necessária para que uma adequada reabilitação bucal seja executada, devolvendo, assim, função e estética perdidas. Objetivo: descrever um caso clínico de reabilitação em paciente bruxista, com presença de desgastes dentários, desgastes de tratamentos restauradores previamente existentes, fratura de onlay e bordas incisais, restabelecendo uma nova DVO por meio de onlays posteriores em cerômeros, recuperando a estética com restaurações diretas em resinas compostas nos dentes anteriores. Conclusões: a reabilitação bucal com levante de mordida em onlays devolve a DVO perdida de maneira segura.

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O aprimoramento da odontologia estética restauradora está ligado ao desenvolvimento de materiais e técnicas inovadoras, os quais podem oferecer diversos benefícios, incluindo a integração cromática, policromatismo, forma anatômica, função, adequado contato proximal e aumento da integridade marginal. Em função desses aspectos, as restaurações de resina composta, aplicadas de forma direta, tendem a ganhar maior longevidade. Assim, o objetivo do presente relato de caso é fornecer ao leitor a visão dos desafios restauradores envolvidos no reparo de uma fratura classe IV de um dente incisivo superior, utilizando-se um novo sistema de resina composta híbrida nanoparticulada (FiltekTM Supreme - 3M ESPE). Resultados: com base no referido material e técnica, otimizamos a obtenção de resultados satisfatórios alcançados por meio da utilização adequada do sistema adesivo e resina composta, mantidos com sucesso após o acompanhamento de 4 anos. Conclusão: pode-se concluir que, interagindo técnica adequada de aplicação, princípios adesivos básicos e materiais de qualidade, o clínico pode garantir o sucesso na restauração da forma, função e estética de dentes anteriores.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)