Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-04T20:46:57Z No. of bitstreams: 1 LucioMauroSouzaBorges_DISSERT.pdf: 4799735 bytes, checksum: 79d871fbe0b0a5ebf018035ed6367963 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-11T19:18:03Z (GMT) No. of bitstreams: 1 LucioMauroSouzaBorges_DISSERT.pdf: 4799735 bytes, checksum: 79d871fbe0b0a5ebf018035ed6367963 (MD5) / Made available in DSpace on 2016-01-11T19:18:03Z (GMT). No. of bitstreams: 1 LucioMauroSouzaBorges_DISSERT.pdf: 4799735 bytes, checksum: 79d871fbe0b0a5ebf018035ed6367963 (MD5) Previous issue date: 2014-01-24 / Este trabalho consiste na concep??o, desenvolvimento e implementa??o de um M?dulo Computacional CAE contendo algoritmos para a an?lise de tens?es e deforma??es integrado a um software acad?mico de visualiza??o denominado OrtoCAD. Os algoritmos de expans?o para a interface CAE que s?o frutos desse trabalho foram desenvolvidos na linguagem FORTRAN objetivando complementar e ampliar as potencialidades de dois trabalhos previamente desenvolvidos no ?mbito do PPGEM-UFRN, a saber: projeto e fabrica??o de um Leitor EletroMec?nico e o software OrtoCAD. O OrtoCAD ? uma interface CAD que, originalmente, inclui a visualiza??o 3D de cartuchos prot?ticos a partir de dados gerados por um equipamento (esp?cie de scanner tridimensional simplificado que utiliza engenharia reversa) dotado de um sistema de Leitura Eletro-Mec?nica (LEM). Inicialmente, a geometria de um coto (i.e. parte remanescente de uma perna amputada e onde a pr?tese se encaixa) ? obtida a partir dos dados produzidos pelo equipamento LEM, aplicando-se os conceitos da Engenharia Reversa. O n?cleo FEA proposto aplica os conceitos de teoria da casca, onde uma l?mina 2D ? gerada a partir de um pe?a s?lida 3D oriunda do OrtoCAD. O programa de an?lise de casca desenvolvido utiliza o M?todo dos Elementos Finitos (MEF) para a descri??o da geometria assim como a an?lise de comportamento do material, fazendo a utiliza??o de elementos de base Lagrangeana quadrangular de nove n?s e campo de deslocamento de ordem superior para melhor descri??o do campo de tens?es na espessura. Como resultado o novo m?dulo FEA oferece ?timas vantagens ao prover o OrtoCAD com novas funcionalidades, a saber: possibilitou a independ?ncia dos softwares comerciais de elevado custo; ampliou a biblioteca disponibilizando novas rotinas computacionais que tratam o problema de forma mais real?stica utilizando crit?rios de falhas de engenharia voltados para materiais comp?sitos; melhorou a performance da an?lise FEA ao utilizar um elemento de malha espec?fico que contempla um maior n?mero de n?s e, finalmente, possui a vantagem de ser aberto e customizado oferecendo versatilidade intr?nseca e amplas possibilidades de edi??o, ajuste e/ou otimiza??o que se fa?am necess?rias no futuro / This work consists of the conception, developing and implementation of a Computational Routine CAE which has algorithms suitable for the tension and deformation analysis. The system was integrated to an academic software named as OrtoCAD. The expansion algorithms for the interface CAE genereated by this work were developed in FORTRAN with the objective of increase the applications of two former works of PPGEM-UFRN: project and fabrication of a Electromechanincal reader and Software OrtoCAD. The software OrtoCAD is an interface that, orinally, includes the visualization of prothetic cartridges from the data obtained from a electromechanical reader (LEM). The LEM is basically a tridimensional scanner based on reverse engineering. First, the geometry of a residual limb (i.e., the remaining part of an amputee leg wherein the prothesis is fixed) is obtained from the data generated by LEM by the use of Reverse Engineering concepts. The proposed core FEA uses the Shell's Theory where a 2D surface is generated from a 3D piece form OrtoCAD. The shell's analysis program uses the well-known Finite Elements Method to describe the geometry and the behavior of the material. The program is based square-based Lagragean elements of nine nodes and displacement field of higher order to a better description of the tension field in the thickness. As a result, the new FEA routine provide excellent advantages by providing new features to OrtoCAD: independency of high cost commercial softwares; new routines were added to the OrtoCAD library for more realistic problems by using criteria of fault engineering of composites materials; enhanced the performance of the FEA analysis by using a specific grid element for a higher number of nodes; and finally, it has the advantage of open-source project and offering customized intrinsic versatility and wide possibilities of editing and/or optimization that may be necessary in the future

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-26T20:16:37Z No. of bitstreams: 1 AnaLuisaDeBarrosPascoal_DISSERT.pdf: 1689211 bytes, checksum: 370df885675ac064f8be47a40a7d2cf4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-08T21:50:09Z (GMT) No. of bitstreams: 1 AnaLuisaDeBarrosPascoal_DISSERT.pdf: 1689211 bytes, checksum: 370df885675ac064f8be47a40a7d2cf4 (MD5) / Made available in DSpace on 2016-08-08T21:50:09Z (GMT). No. of bitstreams: 1 AnaLuisaDeBarrosPascoal_DISSERT.pdf: 1689211 bytes, checksum: 370df885675ac064f8be47a40a7d2cf4 (MD5) Previous issue date: 2016-03-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os m?todos tradicionais de confec??o de pr?teses totais exigem uma ampla sequ?ncia de procedimentos cl?nicos e laboratoriais, entretanto, n?o h? evid?ncia cient?fica de que eles produzam resultados superiores aos m?todos simplificados. Objetivo: Avaliar a efetividade de uma t?cnica simplificada (S) para confec??o de pr?tese total, comparando-a a tradicional (T), atrav?s da efici?ncia mastigat?ria e da avalia??o da qualidade das pr?teses. M?todo: Realizou-se um ensaio cl?nico controlado randomizado com 50 pacientes, 25 reabilitados com pr?teses totais duplas produzidas pela t?cnica tradicional e 25 reabilitados por uma t?cnica simplificada. Avaliou-se a efici?ncia mastigat?ria pelo m?todo colorim?trico com o aux?lio de uma c?psula mastigat?ria. A qualidade das pr?teses foi obtida por meio do instrumento desenvolvido por Sato et al. em 1998. Resultados: 39 pacientes conclu?ram o estudo, sendo 18 do grupo tradicional e 21 do grupo simplificado. N?o houve diferen?a entre os grupos para a efici?ncia mastigat?ria (p=0.835). Um paciente apresentou pr?tese com qualidade ruim (grupo S), nove com qualidade regular (T= 3; S=6) e 29 pacientes apresentaram pr?teses com qualidade boa (T= 15; S= 14), sem diferen?as entre os grupos. A qualidade das pr?teses obteve diferen?a significativa para a atura do rebordo inferior (p=0.05). Conclus?o: as pr?teses totais duplas confeccionadas pelo m?todo simplificado foram consideradas eficazes do ponto de vista da efici?ncia mastigat?ria e da qualidade das pr?teses, apresentando resultados semelhantes ?s confeccionadas pelo m?todo tradicional. / Traditional methods for dentures fabrication require a wide clinical and laboratory procedures; however, there is no scientific evidence that these methods can produce better results when compared with simplified methods. Aim: To evaluate the effectiveness of a simplified methods for denture fabrication, comparing it to the traditional one through masticatory efficiency and prosthesis quality. Method: A randomized controlled trial was conducted with 50 patients, 25 rehabilitated with prosthesis produced by traditional technique and 25 rehabilitated by a simplified technique. The masticatory efficiency was evaluated by colorimetric method, using chewing capsules. The quality of prosthesis was obtained using a reliable and reproducible instrument. Statistical analysis of the masticatory efficiency and quality of the prosthesis was obtained by the Mann-Whitney test. Results: 39 patients completed the study, 18 on traditional group and 21 on simplified group. There was no difference between groups for the masticatory efficiency (p = 0.835) and the quality of the prosthesis (p = 0672). The evaluation of the overall quality of the prosthesis according to oral conditions, demonstrated significant difference on the height of the mandibular ridges (p = 0.010) and mandibular muscle attachments (p = 0.039). Conclusion: Complete dentures fabricated by simplified method were considered effective from the point of view of masticatory efficiency and quality of prosthetics, with results similar to those made by the traditional method.

Made available in DSpace on 2014-12-17T14:57:43Z (GMT). No. of bitstreams: 1 EdsonJAP.pdf: 1427766 bytes, checksum: 2d062c892b501f8f46093e7d7c17a9b2 (MD5) Previous issue date: 2007-08-10 / The manufacturing of above and below-knee prosthesis starts by taking surfac measurements of the patient s residual limb. This demands the making of a cartridg with appropriate fitting and customized to the profile of each patient. The traditiona process in public hospitals in Brazil begins with the completion of a record file (according to law n?388, of July 28, 1999 by the ministry of the health) for obtaining o the prosthesis, where it is identified the amputation level, equipment type, fitting type material, measures etc. Nowadays, that work is covered by the Brazilian Nationa Health Service (SUS) and is accomplished in a manual way being used commo measuring tapes characterizing a quite rudimentary, handmade work and without an accuracy.In this dissertation it is presented the development of a computer integrate tool that it include CAD theory, for visualization of both above and below-knee prosthesis in 3D (i.e. OrtoCAD), as well as, the design and the construction a low cos electro-mechanic 3D scanner (EMS). This apparatus is capable to automatically obtain geometric information of the stump or of the healthy leg while ensuring smalle uncertainty degree for all measurements. The methodology is based on reverse engineering concepts so that the EMS output is fed into the above mentioned academi CAD software in charge of the 3D computer graphics reconstruction of the residualimb s negative plaster cast or even the healthy leg s mirror image. The obtained results demonstrate that the proposed model is valid, because it allows the structura analysis to be performed based on the requested loads, boundary conditions, material chosen and wall thickness. Furthermore it allows the manufacturing of a prosthesis cartridge meeting high accuracy engineering patterns with consequent improvement in the quality of the overall production process / A fabrica??o de pr?teses para amputados de membros inferiores (transfemural e transtibial) exige a confec??o de um cartucho com encaixe adequado e personalizado ao perfil de cada paciente. O processo tradicional de atendimento a pacientes em hospitais p?blicos no Brasil inicia-se com o preenchimento de uma ficha conforme portaria n?388, de 28 de Julho de 1999 do minist?rio da sa?de para obten??o da pr?tese, onde ? identificado o n?vel de amputa??o, tipo de equipamento, tipo de encaixe, material, medidas etc. Atualmente, esses cartuchos s?o fabricados de forma manual atrav?s de instrumentos de baixa precis?o, caracterizando um trabalho bastante rudimentar, artesanal e sem nenhuma acuracidade. Nesta disserta??o prop?e-se o desenvolvimento de uma ferramenta integrada que envolva o CAD, para visualiza??o das pr?teses dos tipos transfemural/transtibial em 3D (OrtoCAD), bem como, o projeto e a constru??o um leitor eletromec?nico (esp?cie de scanner tridimensional), capaz de obter automaticamente e qualitativamente, com menor grau de incerteza as informa??es geom?tricas do coto ou da perna sadia. A metodologia inclui a aplica??o de conceitos de engenharia reversa para gerar computacionalmente a representa??o do coto e/ou a imagem reversa do membro sadio. Os resultados obtidos demonstram que o modelo posposto ? v?lido, pois permite a an?lise estrutural em fun??o do carregamento solicitado e a confec??o de um cartucho de pr?tese atendendo elevados padr?es de acuracidade da engenharia com conseq?ente melhoria na qualidade do processo de fabrica??o

Made available in DSpace on 2014-12-17T14:57:47Z (GMT). No. of bitstreams: 1 WilliamFQ.pdf: 3530709 bytes, checksum: e7ebfa713499f96e35732090f0094f3f (MD5) Previous issue date: 2008-08-07 / The manufacture of prostheses for lower limb amputees (transfemural and transtibial) requires the preparation of a cartridge with appropriate and custom fit to the profile of each patient. The traditional process to the patients, mainly in public hospitals in Brazil, begins with the completion of a form where types of equipment, plugins, measures, levels of amputation etc. are identified. Currently, such work is carried out manually using a common metric tape and caliper of wood to take the measures of the stump, featuring a very rudimentary, and with a high degree of uncertainty geometry of the final product. To address this problem, it was necessary to act in two simultaneously and correlated directions. Originally, it was developed an integrated tool for viewing 3D CAD for transfemoral types of prostheses and transtibial called OrtoCAD I. At the same time, it was necessary to design and build a reader Mechanical equipment (sort of three-dimensional scanner simplified) able to obtain, automatically and with accuracy, the geometric information of either of the stump or the healthy leg. The methodology includes the application of concepts of reverse engineering to computationally generate the representation of the stump and/or the reverse image of the healthy member. The materials used in the manufacturing of prostheses nor always obey to a technical scientific criteria, because, if by one way it meets the criteria of resistance, by the other, it brings serious problems mainly due to excess of weight. This causes to the user various disorders due to lack of conformity. That problem was addressed with the creation of a hybrid composite material for the manufacture of cartridges of prostheses. Using the Reader Fitter and OrtoCAD, the new composite material, which aggregates the mechanical properties of strength and rigidity on important parameters such as low weight and low cost, it can be defined in its better way. Besides, it brings a reduction of up steps in the current processes of manufacturing or even the feasibility of using new processes, in the industries, in order to obtain the prostheses. In this sense, the hybridization of the composite with the combination of natural and synthetic fibers can be a viable solution to the challenges offered above / A fabrica??o de pr?teses para amputados de membros inferiores (transfemural e transtibial) exige a confec??o de um cartucho com encaixe adequado e personalizado ao perfil de cada paciente. O processo tradicional de atendimento a pacientes, principalmente, em hospitais p?blicos no Brasil, inicia-se com o preenchimento de uma ficha onde s?o identificados os n?veis de amputa??o, tipos de equipamentos, encaixes, medidas etc. Atualmente, esse trabalho ? realizado de forma manual utilizando-se fitas m?tricas comuns e paqu?metro de madeira para tomada das medidas do coto caracterizando um trabalho bastante rudimentar, e com um alto grau de incerteza geom?trica do produto final. Para abordar esse problema foi necess?rio partir em duas dire??es simult?neas e correlatas. Inicialmente desenvolveu-se uma ferramenta integrada CAD de visualiza??o 3D para pr?teses dos tipos transfemoral e a transtibial denominado OrtoCAD I. Ao mesmo tempo em que se fez necess?rio projetar e construir um equipamento Leitor Mec?nico (esp?cie de scanner tridimensional simplificado) capaz de obter, automaticamente e com acuracidade, as informa??es geom?tricas do coto ou da perna sadia. A metodologia inclui a aplica??o de conceitos de engenharia reversa para gerar computacionalmente a representa??o do coto e/ou a imagem reversa do membro sadio. Os materiais usados na fabrica??o dessas pr?teses nem sempre obedecem a um crit?rio t?cnico cientifico, pois se por um lado atende ao crit?rio de resist?ncia por outro traz s?rios problemas devido principalmente ao excesso de peso. Isso causa diversos transtornos ao usu?rio devido ? falta de conformidade. Esse problema foi abordado com a cria??o de um material comp?sito hibrido para fabrica??o de cartuchos de pr?teses. Com o uso do Leitor Mec?nico e do OrtoCAD I o novo material comp?sito, que agrega as propriedades mec?nicas de resist?ncia e rigidez com par?metros importantes como baixo peso e baixo custo, pode ser dimensionado de forma correta. Alem disso consegue-se uma redu??o de etapas nos atuais processos de fabrica??o ou at? mesmo a viabilidade de uso de novos processos, no ?mbito industrial, na obten??o das pr?teses. Neste sentido, a hibridiza??o do comp?sito com a combina??o entre fibras sint?ticas e naturais pode ser uma solu??o vi?vel aos desafios propostos acima

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 IedaNSM.pdf: 5948604 bytes, checksum: dbf245a349dd04cff535e8ba2e89601d (MD5) Previous issue date: 2007-07-06 / The aim of this work was to study a series of 11 different compositions of Ti-Zr binary alloys resistance to aggressive environment, i. e., their ability to keep their surface properties and mass when exposed to them as a way to evaluate their performance as biomaterials. The first stage was devoted to the fabrication of tablets from these alloys by Plasma-Skull casting method using a Discovery Plasma machine from EDG Equipamentos, Brazil. In a second stage, the chemical composition of each produced tablet was verified. In a third stage, the specimen were submitted to: as-cast microstructure analysis via optical and scanning electron microscopy (OM and SEM), x-ray dispersive system (EDS) chemical analysis via SEM, Vickers hardness tests for mechanical evaluation and corrosion resistence tests in a 0.9% NaCl solution to simulate exposition to human saliva monitored by open circuit potential and polarization curves. From the obtained results, it was possible to infer that specimens A1 (94,07 wt% Ti and 5,93% wt% Zr), A4 (77,81 wt % Ti and 22,19 wt % Zr) and A8 (27,83 wt% Ti and 72,17 wt% Zr), presented best performance regarding to corrosion resistance, homogeneity and hardness which are necessary issues for biomaterials to be applied as orthopedic and odontological prosthesis / Este trabalho teve como finalidade estudar uma s?rie de onze ligas met?licas bin?rias, tit?nio zirc?nio, quanto ? capacidade de resistirem ?s deteriora??es sem sofrerem modifica??es de suas propriedades iniciais de massa e superf?cie quando expostas a meios agressivos, como condi??o fundamental para que as mesmas sejam aplicadas como biomateriais. A primeira etapa tratou da confec??o das amostras das ligas em forma de pastilhas, empregando-se o processo de fundi??o Plasma Skull realizado na m?quina Discovery Plasma, produzida no Brasil pela EDG Equipamentos. Na segunda etapa, as amostras confeccionadas foram submetidas aos ensaios para a determina??o da composi??o qu?mica resultante de cada liga da s?rie ap?s a fus?o. E durante a terceira etapa foram feitos os procedimentos de avalia??es das amostras quanto ? homogeneidade e apresenta??o da microestrutura de cada uma das ligas no estado bruto de fus?o, como resultados dos ensaios metalogr?ficos por microscopia ?ptica e microscopia eletr?nica de varredura acoplada a espectroscopia por energia dispersiva de raios-x; quanto ? propriedade mec?nica de dureza medida em escala Vickers (HV); e quanto ?s propriedades qu?micas de resist?ncia ? corros?o, quando expostas em solu??o de cloreto de s?dio 0,9 %, para simular a saliva, empregando-se o monitoramento do potencial de circuito aberto e as curvas de polariza??o. A partir dos resultados obtidos foi poss?vel identificar as pastilhas de composi??es qu?micas A1 (94,07% de Ti e 5,93% de Zr), A4 (77,81% de Ti e 22,19% de Zr) e A8 (27,83% de Ti e 72,17% de Zr) que resultaram como maiores detentoras do conjunto de propriedades de resist?ncia ? corros?o, homogeneidade e dureza, as quais s?o mais necess?rias em biomateriais tipo pr?teses ortop?dicas ou odontol?gicas

Made available in DSpace on 2014-12-17T14:07:01Z (GMT). No. of bitstreams: 1 HarrisonAD.pdf: 3488100 bytes, checksum: 805801db06d21e5667735d16a5799fe2 (MD5) Previous issue date: 2008-05-30 / The cobalt-chromium alloy is extensively used in the Odontology for the confection of metallic scaffolding in partial removable denture. During the last few years, it has been reported an increasing number of premature imperfections, with a few months of prosthesis use. The manufacture of these components is made in prosthetic laboratories and normally involves recasting, using parts of casting alloy and parts of virgin alloy. Therefore, the objective of the present study was to analyze the mechanical properties of a commercial cobalt-chromium alloy of odontological use after successive recasting, searching information to guide the dental prosthesis laboratories in the correct manipulation of the cobalt-chromium alloy in the process of casting and the possible limits of recasting in the mechanical properties of this material. Seven sample groups were confectioned, each one containing five test bodies, divided in the following way: G1: casting only with virgin alloy; G2: casting with 50% of the alloy of the G1 + 50% of virgin alloy; G3: casting with 50% of the alloy of the G2 + 50% of virgin alloy; G4: casting with 50% of the alloy of the G3 + 50% of virgin alloy; G5: 50% of alloy of the G4 + 50% of virgin alloy; G6: 50% of alloy of the G5 + 50% of virgin alloy and finally the G7, only with recasting alloy. The modifications in the mechanical behavior of the alloy were evaluated. Moreover, it was carried the micro structural characterization of the material by optic and electronic scanning microscopy, and X ray diffraction.and fluorescence looking into the correlatation of the mechanical alterations with structural modifications of the material caused by successive recasting process. Generally the results showed alterations in the fracture energy of the alloy after successive recasting, resulting mainly of the increasing presence of pores and large voids, characteristic of the casting material. Thus, the interpretation of the results showed that the material did not reveal significant differences with respect to the tensile strength or elastic limit, as a function of successive recasting. The elastic modulus increased from the third recasting cycle on, indicating that the material can be recast only twice. The fracture energy of the material decreased, as the number of recasting cycles increased. With respect to the microhardness, the statistical analyses showedno significant differences. Electronic scanning microscopy revealed the presence of imperfections and defects, resulting of the recasting process. X ray diffraction and fluorescence did not show alterations in the composition of the alloy or the formation of crystalline phases between the analyzed groups. The optical micrographs showed an increasing number of voids and porosity as the material was recast. Therefore, the general conclusion of this study is that the successive recasting of of Co-Cr alloys affects the mechanical properties of the material, consequently leading to the failure of the prosthetic work. Based on the results, the best recommendadition is that the use of the material should be limited to two recasting cycles / Ligas cobalto-cromo s?o extensivamente utilizadas na Odontologia para a confec??o de arma??es met?licas em pr?teses parciais remov?veis. Durante os ?ltimos anos, tem sido reportado um n?mero crescente de falhas prematuras, com poucos meses de utiliza??o das pr?teses. A fabrica??o desses componentes ? feita em laborat?rios prot?ticos e normalmente envolve a refundi??o, utilizando partes de liga fundida e partes de liga virgem. Portanto, o objetivo do presente estudo foi analisar as propriedades mec?nicas de uma liga comercial de cobalto-cromo de uso odontol?gico ap?s sucessivas refundi??es, buscando informa??es no sentido de orientar os laborat?rios de pr?tese dent?ria na correta manipula??o dessa liga no processo de fundi??o e nos poss?veis limites de refundi??o desse material. Foram confeccionados sete grupos de amostras, cada um contendo cinco corpos de prova, divididos da seguinte maneira: G1: fundi??o apenas com liga virgem; G2: fundi??o com 50% da liga do G1 + 50% de liga virgem; G3: fundi??o com 50% da liga do G2 + 50% de liga virgem; G4: fundi??o com 50% da liga do G3 + 50% de liga virgem; G5: 50% de liga do G4 + 50% de liga virgem; G6: 50% de liga do G5 + 50% de liga virgem e finalmente o G7, s? com liga refundida. Foram avaliadas as principais modifica??es ocorridas no comportamento mec?nico dessa liga por meio de ensaios de tra??o e microdureza. Al?m disso, foi realizada a caracteriza??o microestrutural do material por meio de microscopia ?ptica e eletr?nica de varredura, difra??o e fluoresc?ncia de raios X procurando correlacionar as altera??es mec?nicas com modifica??es estruturais do material ocasionadas pelos sucessivos processos de refundi??o. De forma geral os resultados mostraram altera??es na plasticidade e energia de fratura da liga ap?s sucessivas refundi??es, decorrentes principalmente da crescente presen?a de poros e vazios, defeitos caracter?sticos da fundi??o do material. A interpreta??o dos resultados permitiu concluir que o material n?o apresentou diferen?as significativas em rela??o ? resist?ncia ? tra??o ou ao limite el?stico, em fun??o das sucessivas refundi??es. A energia de fratura do material mostrou tend?ncia ? diminui??o, ? medida que o material foi refundido. Em rela??o ? microdureza, as an?lises estat?sticas mostraram n?o haver diferen?as significativas. A microscopia eletr?nica revelou a presen?a de falhas e defeitos, resultantes dos processos de refundi??es. A an?lise por fluoresc?ncia e difra??o de raios X n?o mostrou altera??es na composi??o da liga ou na forma??o de fases cristalinas entre os grupos analisados. As micrografias ?pticas mostraram um crescente n?mero de vazios e aumento da porosidade ? medida que o material foi refundido. Assim, a conclus?o geral do trabalho ? que as sucessivas refundi??es em ligas de Co-Cr comprometem as propriedades mec?nicas do material, o que pode levar a falhas e consequentemente, ao fracasso do trabalho prot?tico. Com base nos resultados, o mais recomendado ? a utiliza??o de no m?ximo duas refundi??es, para que as propriedades do material n?o sejam comprometidas