42 resultados para AXIAL CHIRALITY


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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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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The current study used strain gauge analysis to perform an in vitro evaluation of the effect of axial and non-axial loading on implant-supported fixed partial prostheses, varying the implant placement configurations and the loading points. Three internal hexagon implants were embedded in the center of each polyurethane block with in-line and offset placements. Microunit abutments were connected to the implants using a torque of 20 N.cm, and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n = 10). Four strain gauges (SGs) were bonded onto the surfaces of the blocks, tangentially to the implants: SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments using a 10-N.cm torque, and axial and non-axial loads of 30 kg were applied at 5 predetermined points. The data obtained from the strain gauge analyses were analyzed statistically through the repeated measures analysis of variance and the Tukey test, with a conventional level of significance of P < 0.05. The results showed a statistically significant difference for the loading point (P = 0.0001), with point E (nonaxial) generating the highest microstrain (327.67 mu epsilon) and point A (axial) generating the smallest microstrain (208.93 mu epsilon). No statistically significant difference was found for implant placement configuration (P = 0.856). It was concluded that the offset implant placement did not reduce the magnitude of microstrain around the implants under axial and non-axial loading conditions, although loading location did influence this magnitude.

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O objetivo nesta pesquisa consiste em fazer um trabalho de prevenção junto às instituições APAE (Associação de Pais e Amigos de Excepcionais) e ASIN (Associação de síndrome de Down), ambas de São José dos Campos e ASPAD (Associação de Pais e Amigos de síndrome de Down) de Jacareí, orientando e avaliando sobre a presença ou não da instabilidade atlanto-axial (IAA), assim como verificar a prevalência dessa anormalidade nesses indivíduos. Foram convidados a participar do projeto todos os indivíduos das três instituições de assistência à SD, tendo formado uma amostra com 68 indivíduos, com idades entre 2 a 34 anos, sendo 39 do sexo masculino e 29 do feminino. Foram realizadas radiografias da coluna cervical nas posições de extensão, flexão e neutra, para as quais todos os responsáveis assinaram termo de consentimento. A verificação da IAA foi feita pela análise da distância atlanto-odontóide (DAO), utilizando o programa Radiocef, com uma ferramenta criada para isso. A DAO foi analisada nas três incidências, e era considerada a presença de IAA desde que o indivíduo apresentasse valores ?4,5mm em pelo menos uma dessas posições. Após a realização dos testes estatísticos e análise dos resultados, concluímos que a prevalência de IAA foi de 22,1% dos indivíduos, com valores DAO entre 4,5 e 8,83mm, tendo sido mais prevalente nos indivíduos do sexo masculino do que feminino, assim como nas crianças do que nos jovens e adultos. Foi possível verificar também que, a posição de flexão apresentou maior prevalência de IAA, mas que ela não deve sobrepor às posições de extensão e neutra, pois pode omitir casos ausentes em flexão, mas presentes nas outras posições. Dessa forma, foi realizado o trabalho de prevenção com a avaliação da IAA por meio da realização dos exames radiográficos em que os laudos... (Resumo completo, clicar acesso eletrônico abaixo)

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When materials for application in aircraft structural components are studied, it must be considered that they will be submitted to cyclic loading, and this is an important parameter to design the study in fatigue life of the materials. Whereas, for example, a landing gear operation, the study of fatigue life and corrosion in the materials used in it is essential, especially when you want to use new techniques for surface treatments. The objective is to study the influence of surface treatment of immersion ion implantation nitrogen plasma, in axial fatigue of Stainless steel 15-5 PH in 39-42 HRC condition. Stainless steel 15-5 PH was tested in axial fatigue and corrosion in salt spray. It was also performed microindentation tests, optical microscopy for microstructural analysis and scanning electron microscopy for fractographic analysis. It was observed that the 3IP had no effect on the thickness of the material and not the hardness of it, and still provided a significant increase in fatigue life of the material

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The aim of this in vitro study was to use strain gauge (SG) analysis to compare the effects of the implant-abutment joint, the coping, and the location of load on strain distribution in the bone around implants supporting 3-unit fixed partial prostheses. Three external hexagon (EH) implants and 3 internal hexagon (IH) implants were inserted into 2 polyurethane blocks. Microunit abutments were screwed onto their respective implant groups. Machined cobalt-chromium copings and plastic copings were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in a cobalt-chromium alloy (n = 5): group 1 = EH/machined. group 2 = EH/plastic, group 3 = IH/machined, and group 4 = IH/plastic. Four SGs were bonded onto the surface of the block tangentially to the implants. Each metallic structure was screwed onto the abutments and an axial load of 30 kg was applied at 5 predetermined points. The magnitude of microstrain on each SG was recorded in units of microstrain (mu epsilon). The data were analyzed using 3-factor repeated measures analysis of variance and a Tukey test (alpha = 0.05). The results showed statistically significant differences for the type of implant-abutment joint, loading point, and interaction at the implant-abutment joint/loading point. The IH connection showed higher microstrain values than the EH connection. It was concluded that the type of coping did not interfere in the magnitude of microstrain, but the implant/abutment joint and axial loading location influenced this magnitude.

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Pós-graduação em Pesquisa e Desenvolvimento (Biotecnologia Médica) - FMB

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Purpose: This study used 12 photoelastics models with different height and thickness to evaluate if the axial loading of 100N on implants changes the morphology of the photoelastic reflection. Methods: For the photoelastic analysis, the models were placed in a reflection polariscope for observation of the isochromatic fringes patterns. The formation of these fringes resulted from an axial load of 100N applied to the midpoint of the healing abutment attached to the implant with 10.0mm x 3.75mm (Conexão, Sistemas de Próteses, Brazil). The tension in each photoelastic model was monitored, photographed and observed using the software Phothoshop 7.0. For qualitative analysis, the area under the implant apex was measured including the green band of the second order fringe of each model using the software Image Tool. After comparison of the areas, the performance generated by each specimen was defined regarding the axial loading. Results: There were alterations in area with different height and thickness of the photoelastic models. It was observed that the group III (30mm in height) presented the smallest area. Conclusion: There was variation in the size of the areas analyzed for different height and thickness of the models and the morphology of the replica may directly influence the result in researches with photoelastic models.