Facetas de Porcelana VS Facetas de Resina Composta

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

Cuaderno de diseño. Asesoría técnica y desarrollo de nuevos productos de cerámica, gres y porcelana. Ráquira – Boyacá.

117 hojas: fotografías.

Elementos de tecnología cerámica. Misión China en Ráquira proyecto cerámica y porcelana.

34 hojas : ilustraciones, fotografías.

Elaboración de porcelana.

[96] hojas : ilustraciones.

Investigación y elaboración artesanal de porcelana en Ráquira, sexto informe.

[272] hojas : ilustraciones, fotografías.

Caracterização Microestrutural e Tribocorrosiva de Sistemas Metalocerâmicos Odontológicos do Tipo Ni-Cr/Porcelana E Ni-Cr/Ti/Porcelana

The partial fixed prosthodontics restoration is used to rehabilitate form and function of partial or total compromised teeth, having to remain permanently joined to remainder tooth. The most useful material on prosthodontics is the feldspar porcelain, commercialized as aluminosilicate powders. Dental porcelains are presented with limited mechanical properties to rehabilitate extensive spaces. The association with Ni-Cr metallic systems (metal-ceramic system) allows that the metallic substructure compensates the fragile porcelain nature, preserving the thermal insulation and aesthetics desirable, as well as reducing the possibility of cracking during matication efforts. Cohesive flaws by low mechanical strength connect the metallic substructure to the oral environment, characterized by a electrolytic solution (saliva), by aggressive temperature, pH cyclic changes and mechanical requests. This process results on ionic liberation that could promote allergic or inflammatory responses, and/or clinical degradation of ceramometal system. The aim of this study was to evaluate the presence of an intermediate titanium layer on the microscopic fracture behavior of porcelains on ceramometal systems. Plasma deposition of titanium films result in regular passivating oxide layers which act as barriers to protect the metallic substrate against the hazardous effects of corrosive saliva. Tribocorrosion tests were performed to simulate the oral environment and mechanical stress, making it possible the early detection of crack formation and growth on metal-ceramic systems, which estimate the adherence between the compounds of this system. Plain samples consisting of dental feldspar porcelain deposited either onto metallic substrates or titanium films were fired and characterized by scanning electron microscopy. The result showed that the titanium film improved the adherence of the system compared to conventional metal-ceramic interfaces, thus holding crack propagation

Obtenção de uma porcelana dielétrica a partir de matérias-primas do Rio Grande do Norte

The dielectric porcelain is usually obtained by mixing various raw materials proportions and is used in the production of electronic equipment for various applications, from capacitors of high and low Power to insulators for low, medium, high and extra high voltage, which are used in distribution lines and transmission of electricity.This work was directed to the s tudy of technological properties of technic porcelain, made from raw materials extracted from pegmatites found in the regions of Seridó and the Alto Oeste of Rio Grande do Norte, which are made of kaolin, quartz and feldspar, abundant and high quality in these regions. The technic ceramics were obtained by mixing in appropriate levels, kaolin, feldspar, quartz and clay, the last item from a pottery in the city of Sao Gonçalo do Amarante, Rio Grande do Norte. During the development the following characterizations correlated to raw materials were made: laser particle sizing, x-ray diffraction, DTA and TG. The compositions studied were formed by uniaxial pressing at a pressure of 50 MPa and sintered at temperatures ranging from 1150 to 1350ºC and levels (times) of sintering between 30, 60, 90 and 120 minutes. The characterization of the samples were taken from the analysis of weight loss, linear shrinkage, porosity, stoneware curve, bulk density, flexural strength of three points, SEM and X-ray diffraction, TMA, Dielectric and cross Resistivity. The studied materials can be employed in producing the objects used in electrical engineering such as: insulators for low, medium and high-voltage electrical systems, command devices, bushing insulation for transformers, power capacitors, spark plugs, receptacles for fluorescent and incandescent light bulbs and others

Efeito das variáveis laboratoriais protéticas na adesão da porcelana com ligas de níquel-cromo

The metalceramic crowns are usually used in dentistry because they provide a resistant structure due to its metallic base and its aesthetics from the porcelain that recovers this structure. To manufacture these crowns, a series of stages should be accomplished in the prosthetic laboratories, and many variables can influence its success. Changes in these variables cause alterations in the metallic alloy and in the porcelain, so, as consequence, in the adhesion between them. The composition of the metal alloy can be modified by recasting alloys, a common practice in some prosthetic laboratories. The aim of this paper is to make a systematic study investigating metalceramic crowns as well as analyzing the effect of recasting Ni-Cr alloys. Another variable which can influence the mechanism of metalceramic union is the temperature used in firing porcelain procedure. Each porcelain has to be fired in a fixed temperature which is determined by the manufacturer and its change can cause serious damages. This research simulate situations that may occur on laboratory procedures and observe their consequences in the quality of the metalceramic union. A scanning eletron microscopy and an optic microscopy were accomplish to analyse the metal-ceramic interface. No differences have been found when remelting alloys were used. The microhardness were similar in Ni-Cr alloys casted once, twice and three times. A wettability test was accomplished using a software developed at the Laboratório de Processamento de Materiais por Plasma, on the Universidade Federal do Rio Grande do Norte. No differences were found in the contact angle between the solid surface (metallic substratum) and the tangencial plane to the liquid surface (opaque). To analyse if the temperature of porcelain firing procedure could influence the contact area between metal and porcelain, a variation in its final temperature was achieve from 980° to 955°C. Once more, no differences have been found

Liberação de cálcio e magnésio por cápsulas porosas de porcelana usadas na extração de solução do solo

O uso de cápsulas porosas para extração de solução do solo é interessante por ser um ensaio não-destrutivo. Entretanto, persistem dúvidas sobre a liberação de íons da própria cápsula, que podem contaminar a solução extraída. Foram realizados testes na Faculdade de Ciências Agronômicas/UNESP, Botucatu (SP), com o objetivo de verificar a liberação de Ca e de Mg por cápsulas porosas de porcelana. No primeiro, foram empregados quatro tratamentos: T1 - lavagem das cápsulas com água destilada, forçando sua passagem pelas cápsulas, utilizando uma bomba a vácuo; T2 - lavagem das cápsulas com HCl 0,1 mol L-1, forçando sua passagem pelas cápsulas, utilizando uma bomba a vácuo; T3 - lavagem das cápsulas com água destilada, sem vácuo, e T4 - lavagem das cápsulas com HCl 0,1 mol L-1, sem vácuo, em um tempo de imersão de 24 h (para T3 e T4). No segundo teste, as cápsulas tratadas com HCl 0,1 mol L-1 no primeiro teste foram lavadas com água destilada novamente e deixadas de molho em água destilada e deionizada durante 45 min. Após estes procedimentos, as cápsulas foram imersas em água destilada, tomando-se alícotas desta solução para determinação de pH e dos teores de Ca e Mg após contato com as cápsulas por 0; 0,5; 1,0; 2,0; 4,0 e 24 h. Cada tratamento teve quatro repetições. Não se observou liberação significativa de Ca e Mg das cápsulas porosas para a solução, quando foram preparadas utilizando-se da passagem de HCl 0,1 mol L-1 a vácuo e água destilada, e deixadas, a seguir, em água destilada e deionizada durante 4 h.

Investigação da Interface Metal-Porcelana da Liga Ni-Cr-Mo Soldada a LASER

The interface formed between the metal and the porcelain of a LASER welded Ni-Cr-Mo alloy was studied. The characterization was carried out through optical microscopy, scanning electron microscopy, X-ray dispersive spectroscopy-EDS and mechanical testing by three-point flexion test-TPE in the region LASER welded with and without the porcelain. The porcelain adhesion with the alloy alone is possible after the oxidation of the metallic surface and subsequent application of an adhesive called opaco. The applied porcelain, on the base metal and fusion zone presented some distinct behaviors. After the TPF test the base metal presented fractures while that in the fusion zone was completely gone. One noticed that the region submitted to the LASER welding showed less porcelain adhesion than the region of the base metal due to the microestructural refinement of the fusion zone. These results can be evidenced by the EDS of the studied regions. The TPF had demonstrated that the Ni-Cr-Mo alloy submitted to the LASER welding, undergone significant alterations in its mechanical properties after the application of the porcelain.

Avaliação da influência dos tipos de tratamento superficial da porcelana glazeada na colagem de braquetes ortodônticos

OBJETIVO: o objetivo deste trabalho foi avaliar a influência do tipo de tratamento superficial da porcelana na resistência adesiva da colagem de braquetes ortodônticos e o modo de fratura após a descolagem. METODOLOGIA:foram confeccionados 80 corpos-de-prova de porcelana, divididos em quatro grupos (n = 18) de acordo com os diferentes tratamentos de superfície: (G1) ponta diamantada; (G2) ponta diamantada e silano; (G3) ácido hidrofluorídrico e (G4) ácido hidrofluorídrico e silano. Após o preparo das superfícies, braquetes Edgewise (Morelli) foram colados com resina (Transbond XT, 3M) e submetidos ao teste de cisalhamento. Os resultados foram avaliados estatisticamente pelo teste de Kruskal-Wallis. RESULTADO: o grupo G1 apresentou uma média de resistência de 3,35, o G2 3,97, o G3 2,56 e o G4 3,10. CONCLUSÃO: constatou-se que não houve diferença estatisticamente significativa na resistência adesiva do braquete entre os tipos de tratamentos estudados (p > 0,05) e os modos de fratura ocorreram, em sua grande maioria, na interface braquete/resina. Este estudo indica que todos os tipos de tratamentos apresentados são eficientes para a colagem.

Estudo dos procedimentos utilizados para obtenção de microrretenções na superfície interna da porcelana: avaliação por meio de testes de rugosimetria e microscopia eletrônica de varredura

Pós-graduação em Ciências Odontológicas - FOAR

Avaliação in vitro da microinfiltração marginal em restaurações indiretas inlay de porcelana. Efeito de diferentes agentes cimentantes

Pós-graduação em Ciências Odontológicas - FOAR

Estudo da interface titânio/porcelana, com três porcelanas de ultra baixa fusão, empregando-se microscopia eletrônica de varredura e dilatometria

Pós-graduação em Ciências Odontológicas - FOAR

Microdureza superficial do cimento resinoso de ativado por duas diferentes fontes de luz com interposição de cerômero e porcelana

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)