Orientador: Alexandre Augusto Zaia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-17T13:51:39Z (GMT). No. of bitstreams: 1 Moreira_DannaMota_D.pdf: 2298709 bytes, checksum: 74c928e8904a305bd8054a46f8c5d001 (MD5) Previous issue date: 2011 / Resumo: Dentre os protocolos de irrigação mais utilizados mundialmente, a associação do hipoclorito de sódio (NaOCl) e o EDTA merece destaque. Entretanto, estes agentes químicos podem causar efeitos deletérios nas propriedades químicas e físicas da dentina, além da ação oxidativa do NaOCl interferir no comportamento de materiais restauradores. O uso de agentes redutores tem demonstrado minimizar os efeitos deletérios do NaOCl previamente a procedimentos restauradores. No primeiro estudo que compõe esta tese teve-se como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% no colágeno presente na matriz orgânica da parede dentinária do canal radicular de incisivos bovinos. Foram utilizados oitenta incisivos bovinos aleatoriamente divididos em oito grupos (n=10): G1(Controle): cloreto de sódio 0,9%; G2: NaOCl 5,25% + EDTA 17%; G3: NaOCl 5,25% + EDTA 17% + ácido ascórbico 10%; G4: NaOCl 5,25% + EDTA 17% + ascorbato de sódio 10%; G5: NaOCl 5,25%; G6: EDTA 17%; G7: ácido ascórbico 10%; G8: ascorbato de sódio 10%. Os espécimes foram submetidos à instrumentação e irrigação com as diferentes substâncias químicas auxiliares e em seguida submetidos ao processamento histológico para análise em microscopia de polarização. Os grupos que demonstraram alteração no padrão de birrefringência foram submetidos à análise de absorbância para a confirmação da perda de proteína. Foi possível concluir que o uso do ácido ascórbico 10% e/ou ascorbato de sódio 10% conseguiu restabelecer os valores de retardo óptico antes diminuídos pelo uso de NaOCl 5,25%, associado ou não ao EDTA 17%. Já no segundo estudo, este teve como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% na microdureza Knoop e resistência flexural da dentina radicular bovina. A distribuição dos grupos foi feita de forma similar ao primeiro estudo. Foram utilizados 80 dentes bovinos para o teste de microdureza Knoop e 120 barras de dentina para o ensaio de flexão de 3-pontos. O NaOCl 5,25% reduziu de forma significativa os valores de microdureza Knoop, chegando a afetar a dureza mesmo em grandes profundidades na dentina radicular bovina. A aplicação de ascorbato de sódio conseguiu revertes os valores previamente reduzidos de microdureza. Ficou comprovado que o NaOCl 5,25% afeta de forma negativa a resistência flexural, mas ao se fazer uso do ácido ascórbico após o protocolo de irrigação com NaOCl e EDTA, os valores de resistência flexural foram restabelecidos, chegando mesmo a equiparar-se ao grupo controle / Abstract: Among the auxiliary chemical substances used in Endodontics during chemical-mechanical preparation, sodium hypochlorite (NaOCl) and EDTA have been the most widely recommended. However, irrigant solutions used in endodontic therapy might yield changes in the chemical and physical properties of dentin. Besides, these reagents compromised the bond strengths of some adhesives on root dentin. The aim of the first study was to evaluate the effect of 10% acid ascorbic or 10% sodium ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation with 5.25% sodium hypochlorite, 17% EDTA or 0.9% sodium chloride. Eighty bovine incisors were randomly divided into eight groups (n=10) according to: G1(Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5,25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to histological processing to be analyzed under polarized light microscopy. Absorbance assay was also performed to confirm the loss of collagen. It is possible to conclude that groups treated with 5.25% NaOCl (G2 and G5) presented a significantly different birefringence pattern compared with the control group (p<0.05).The birefringence values reduced could be reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate after 5.25% NaOCl and 17% EDTA irrigation. The absorbance assay of G2 and G5 confirmed the loss of collagen (p<0.05). The second study aimed to evaluate the effect of 10% ascorbic acid or 10% sodium ascorbate application after 5.25% NaOCl, 17% EDTA or 0.9% sodium chloride irrigation in the Knoop microhardness and flexural strength on root dentin. Eighty bovine incisors were randomly divided into eight groups (n=10): G1 (Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5.25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to Knoop microhardness. Standardized plano-parallel dentin bars were prepared and randomly divided into the same eight groups (n=15) cited above. The dentin bars were then loaded to failure in a three-point bend test. Root canal irrigation with 5.25% NaOCl reduced the microhardness of dentin in all distances tested. The microhardness values increased in all distances when sodium ascorbate was used after 5.25% NaOCl and 17% EDTA irrigation. By exposing the dentin bars to 5.25% NaOCl, whether it was associated or not to 17% EDTA, the flexural strength decreased. However, values increased when 10% ascorbic acid or 10% sodium ascorbate were used after 5.25% NaOCl and 17% EDTA irrigation / Doutorado / Endodontia / Doutor em Clínica Odontológica

Made available in DSpace on 2014-10-09T12:48:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:40Z (GMT). No. of bitstreams: 1 09058.pdf: 21604001 bytes, checksum: ed33d13e2bf6f6ac6cacc2bfb598c01d (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:50:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:49Z (GMT). No. of bitstreams: 1 00392.pdf: 1686077 bytes, checksum: 2d791e79c1df9cb836e2dd00406dbad9 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Made available in DSpace on 2014-10-09T12:53:03Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:03Z (GMT). No. of bitstreams: 0 / Este trabalho tem por objetivo obter propriedades mecânicas de compósitos angle-ply fabricados pelo processo de enrolamento filamentar, na forma de placas com diversas orientações do reforço. As placas foram fabricadas com fibra de carbono e matriz epoxídica e fibra de vidro e matriz epoxídica. Os exemplares para ensaio foram obtidos nas direções de 0°, ±10°, ±20°, ±30°, ±60°, ±70°, ±80° e 90° em relação á direção do equipamento de ensaio, atribuída como sendo 0°. Resultados mostraram que para corpos-de-prova de fibra de cartaono bobinados na direção ±10° a tensão máxima média obtida foi de 855 MPa e o módulo de elasticidade médio de 136 GPa, enquanto que para corpos-de-prova de fibra de carbono bobinados na direção de ±80°, a tensão máxima média foi de 68 MPa e módulo de elasticidade médio de 10 GPa. Os resultados obtidos indicaram que as propriedades mecânicas diminuem acentuadamente a partir da direção de ±10°. Também foram obtidas as frações volumétricas, dureza Barcol e análise térmica das placas fabricadas. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:40:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:25Z (GMT). No. of bitstreams: 1 02754.pdf: 4328474 bytes, checksum: 6fdb5d10397ad0fb34056831c731e939 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:30:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:34Z (GMT). No. of bitstreams: 1 01481.pdf: 5222933 bytes, checksum: 404da01814721acc7363f150cb1a7937 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:49:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:58Z (GMT). No. of bitstreams: 1 10382.pdf: 2748014 bytes, checksum: abae13684ec54f32e7a024de8f8bb50f (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:37:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:53Z (GMT). No. of bitstreams: 1 04605.pdf: 6872296 bytes, checksum: 68f8db6ce363174412f8b8adea9626e6 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

M.Ing. / In the design and analysis of components and structures, detailed information on the material behaviour and its properties is required. When a material is loaded dynamically, such as in metal punching, the material properties may not be the same as when loaded statically. This is known as the strain rate sensitivity of a material, which implies that properties such as the yield strength, tensile strength and ductility may vary with the rate at which the material is loaded. South Africa is one of the large stainless steel producing countries. Seventy percent of the known chromium ore reserves are found in the Bushveld Igneous Complex in the Northern Province and Mpumalanga. To compete on the global stainless steel market it is essential that the South African producers have all the relevant product information directly available. Considerable research has been performed on mild steel at different strain rates and temperatures[1]. Work has also been done on some austenitic stainless steels. Very little, or no work has been done in this regard on ferritic and martensitic stainless steels and on the proprietary alloy 3CR12[2]. The aim of this thesis is to investigate the strain rate sensitivity of Types 304, 430 and 316 stainless steel, 3CR12 corrosion resistant steel and mild steel at different temperatures. To achieve this, tensile tests are performed. at strain rates between 10's -1 to approximately 100s -1 and at temperatures ranging from -40°C to 140°C. Shear tests are also performed at various strain rates, to investigate the effect that material behaviour has on a typical metal working process. The results obtained show that all the materials tested are strain rate sensitive. The strain rate sensitivity varies as a function of the material tested and the testing temperature. Constitutive models which take into account the strain rate sensitivity at room temperature for all the materials are also presented. These models describe the behaviour of the material fairly accurately. Three dimensional plots are also presented which depict how the yield strength, tensile strength and elongation vary as a function of both strain rate and temperature. These plots clearly show material trends for the strain rates and temperatures tested.

No description available.