Thesis (M.S.)--University of Michigan, 1988.

Thesis (M.S.)--University of Michigan, 1972.

Soft-paste porcelain was produced in Britain in great quantities between the mid-18th and early 19th centuries. Due to industrial secrecy and the complexities of creating a product that would survive high-temperature firing, a range of paste recipes was employed by dozens of factories. This has resulted in an array of porcelains which vary in their elemental composition and mineralogy. This research carries out a meta-analysis of the published data for porcelain bodies and glazes and concludes that some discrimination can be achieved using the major and minor elemental composition of the bodies, and that for the glazes intra-factory variation is often greater than inter-factory variation in composition. A pilot investigation of the trace elemental composition of British porcelain is carried out using Laser Ablation Inductively Coupled Plasma Mass Spectroscopy, which finds compositional groups corresponding to different sources of clay and silica raw materials. In the interests of preserving intact objects, there is recognised a need for a non-destructive method for analysing British porcelain, in order to provenance and date objects. Such a method would rely on data from the surface of the object, which is typically covered by glaze and over-glaze coloured enamels, and this research demonstrates that the formulae used for the glaze and enamels are in some cases characteristic of the factory, or workshop, and period at which they were created. Hand-Held XRF analysis is used to analyse the glaze, underglaze blue and polychrome enamels on a selection of porcelain objects from different factories, and compositional traits are identified that allow some factories and periods to be distinguished. Glass standards are developed, which are representative of the glaze and enamel composition, and which could allow X-ray fluorescence (XRF) data to be calibrated for fully quantitative results.

Made available in DSpace on 2014-06-11T19:31:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09-18Bitstream added on 2014-06-13T20:01:55Z : No. of bitstreams: 1 kreidler_mam_dr_arafo.pdf: 4013651 bytes, checksum: cf6cbf37929ab40382db0b60e3009ace (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O propósito deste trabalho foi a caracterização da influência do tipo de sinterização na composição química, resistência à flexão e dureza de blocos cerâmicos para CAD/CAM. Foram selecionados quatro tipos de blocos cerâmicos e distribuídos nos seguintes grupos de trabalho, segundo o tipo de sinterização a ser realizada: Grupo G1 - In-Ceram® Alumina / fase líquida; Grupo G2 - In-Ceram® AL / fase sólida; Grupo G3 - In-Ceram® Zircônia / fase líquida; Grupo G4 - In-Ceram® YZ / fase sólida. Todos os blocos cerâmicos foram cortados em forma de barra, com dimensões finais de 25 x 5 x 2 mm após sinterização. Os corpos-de-prova selecionados foram submetidos aos ensaios de resistência à flexão em três pontos e dureza superficial Vickers. Também foram realizadas avaliações por EDS, DRX, MEV; e comparações com suas respectivas amostras verdes. Os resultados, submetidos à análise estatística mostraram que a média da resistência à flexão do grupo G1 (351,7 MPa) e grupo G3 (356,3 MPa), foram significativamente menores que as do grupo G2 (421,9 MPa) e grupo G4 (758,4 MPa); assim também como todas as médias de dureza foram significativamente diferentes, sendo as do grupo G2 (1.936,6 HV 1/30) e G4 (1.321,4 HV 1/30) maiores, quando comparadas com as do grupo G1 (1.173,3 HV 1/30) e G3 (1.094,6 HV 1/30). Conclui-se, que a sinterização via fase sólida demonstrou ser mais eficiente para se obter densificação máxima dos compostos cerâmicos, resultando em elevados valores de resistência à flexão e dureza. / The aim of this study was to characterize the influence of the sintering type in the chemical composition, flexural strength and hardness of an alumina-reinforced ceramics system for CAD/CAM. Four type of ceramic blocks were selected and distributed according to the type of sintering to be performed: Group G1 - In-Ceram® Alumina / liquid state; Group G2 - In-Ceram® AL / solid state; Group G3 - In-Ceram® Zircônia / liquid state; Group G4 - In-Ceram® YZ / solid state. All the ceramic blocks were cut in bar shape with dimensions of 25 x 5 x 2 mm after sintering. The selected specimens were submitted to the three-point bending test and to the Vickers hardness test method. Additionally, evaluations were carried out by EDS, XRD, SEM, and comparisons with their green samples. The results, after statistical analysis, show that the average flexural strength of group G1 (351.7 MPa) and group G3 (356.3 MPa) were significantly lower than those of group G2 (421.9 MPa) and group G4 (758.4 MPa); as well as all hardness averages were significantly different, being higher for group G2 (1.936,6 HV 1/30) and G4 (1.321,4 HV 1/30), when compared to group G1 (1.173,3 HV 1/30) and G3 (1.094,6 HV 1/30). It was concluded that the solid state sintering proved to be more efficient to obtain maximum densification of reinforced ceramics, resulting in high values of flexural strength and hardness.

Made available in DSpace on 2018-07-27T17:13:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2008. Added 1 bitstream(s) on 2018-07-27T17:16:46Z : No. of bitstreams: 1 000893158.pdf: 1650381 bytes, checksum: fd3bc9e34eb119067f5450c18db29074 (MD5) / The objective of this work was to evaluate the adaptation marginal of restoring ceramic total crowns using system IPS 2 Empress and the Ceramcap system at two moments: after confections of copings and after applications of covering ceramics. However, ten stainless steel trunnions, had been tilted producing circular prepare that simulated the dental prepares with line of termination in shoulder of 1, 5 mm, axial walls in 6 degrees of oclusal convergence, rounded off angles to pulpar-axio and occlusal-axio, height of 7 mm, diameter in the base of the 11 preparation of mm and diameter in the oclusal of the preparation of 7, 06 mm. Boxes or concavities had been prevented. After that, they had been molded with silicona of addition and confectioned copings, as recommendations of the manufacturers. The evaluation of the adaptation marginal was made with an optic microscope of visible light with increase of 100 x, connected to system of image collection, had been made 4 images for each body-oftest, was used a software Imagelab 2000 for analysis of the images, where 12 points of mismatch for each image had been collected. The 148 values of mismatch marginal had been analyzed through test T student with level of significance of 5%. For system ceramic IPS 2 Empress and Ceramcap they had been found average of mismatch respectively of (86,1μm and 99,8μm) for copings and of (84,5μm and 97,9 μm), after applied covering ceramics. It had difference significant statistics enters the confection of copings after and the applications of covering ceramics, between the two studied materials. In comparison to the two studied systems, system IPS Empress presented average minors of mismatch...(Complete abstract electronic access below)

Dentro do aspecto estético atual, a harmonia entre a cor do elemento dental e dos materiais restauradores é um dos quesitos mais relevantes e de maior dificuldade técnica. A utilização de aparelhos para a seleção de cor pelo método digital propõese a diminuir o aspecto subjetivo do processo de visão das cores, minimizando dessa forma possíveis falhas do processo. Este estudo simulou três situações clínicas em peças protéticas cerâmicas na forma de três tratamentos de superfície, um desgaste com ponta de carboneto de silício, um glazeamento a frio e um overglaze em forno para porcelana. Em seguida avaliou-se a interferência dos tratamentos na cor de duas marcas comerciais de porcelana, com e sem a presença de saliva, através do método objetivo de seleção de cor, com auxílio de um espectrofotômetro digital intraoral. Concluiu-se que não houve alteração de cor perceptível ao olho humano de nenhum material sob os tratamentos superficiais realizados, porém, entretanto nota-se uma mudança maior da cor para o tratamento overglaze em relação aos demais tratamentos; a diferença de cor causada pela presença de saliva na porcelana Noritake e os valores encontrados para a porcelana Duceram foram valores perceptíveis ao olho humano treinado em seleção de cor; o tratamento overglaze na porcelana Duceram foi o que maior E promoveu, chegando próximo ao limite aceitável; na presença de saliva os valores de E todos aumentaram para a porcelana Noritake e diminuíram para a porcelana Duceram, indicando que as diferentes composições dos materiais alteram seu comportamento; a diferença entre as medidas com e sem saliva para a porcelana Noritake é mais evidente do que para Duceram; o aparelho é falho em algumas interpretações, mas é aceitável para o uso clínico de tomada de cor; o aparelho não é indicado para tomada de cor em estudos científicos; as análises dos dados L*a*b* não são condizentes com as leituras de cor pelas escalas Vita Classical e 3D Master. / Considering the current aesthetic aspect, the harmony between the color of the tooth and dental restorative materials is one of the issues of greatest importance and technical difficulty. The use of apparatus for the selection of color by digital method proposes to reduce the subjective aspect of the vision of colors, thus minimizing possible failures of the process. This study simulated clinical situations in three prosthetic ceramic pieces in the form of three surface treatments, a scattering using silicon carbide bur, a cold glaze and an overglaze in ceramic oven. Then we evaluate the interference of the treatments on the color of the two porcelains, with and without the presence of saliva using the objective method of color matching, with the aid of a digital intraoral spectrophotometer. It was concluded that there was no change in color perceptible to the human eye of any material on the surface treatments carried out, however, there is a greater change in color for the treatment overglaze when compared to other treatments; the difference in color caused by the presence of saliva in the Noritake and the values found for all treatments in Duceram were visible to the human eye trained on color selection; the treatment overglaze on porcelain Duceram caused the highest E , reaching the acceptable limit; in the presence of saliva values of E increased for Noritake and decreased for Duceram, indicating that the different compositions of materials can alter their behavior; the difference between measurements with and without saliva for Noritake porcelain is more evident than for Duceram; the device is deficient in some interpretations, but is acceptable for the clinical use of color matching; the equipment is not indicated for color matching in scientific studies; the analysis of the data La*b* are not consistent with the readings of the color tabs Vita Classical and 3D Master.

Resumo:O objetivo deste trabalho foi avaliar a adaptação marginal de coroas totais cerâmicas utilizando-se o sistema restauradores IPS Empress 2 e o sistema Ceramcap em dois momentos: após confecções dos copings e após aplicações da cerâmica de cobertura. No entanto, dez munhões de aço inoxidáveis, foram torneados produzindo preparos circulares que simulavam os preparos dentais com linha de terminação em ombro de 1, 5 mm, paredes axiais em 6 graus de convergência oclusal, ângulos axio-pulpar e axio-oclusal arredondados, altura de 7 mm, diâmetro na base do preparo de 11 mm e diâmetro na oclusal do preparo de 7, 06 mm. Caixas ou concavidades foram evitadas. Em seguida, foram moldados com silicona de adição e confeccionados os copings, conforme recomendações dos fabricantes. A avaliação da adaptação marginal foi feita com um microscópio óptico de luz visível com aumento de 100 x, acoplado com sistema de coleta de imagem, foram feitas 4 imagens para cada corpo-de-prova, foi utilizado um software Imagelab 2000 para análise das imagens, onde foram coletados 12 pontos de desadaptação para cada imagem. Os valores de desadaptação marginal foram 146 analisados através do teste T student com nível de significância de 5%. Para os sistema cerâmicos IPS Empress 2 e Ceramcap foram encontrados médias de desadaptação respectivamente de (86,1μm e 99,8μm) para os copings e de (84,5μm e 97,9 μm), após aplicado a cerâmica de cobertura. Houve diferença estatística significante entre a confecção dos copings e após as aplicações da cerâmica de cobertura, entre os dois materiais estudados. Em comparação aos dois sistemas estudados, o sistema IPS Empress apresentou menores médias de desadaptação em comparação com o sistema Ceramcap. / Abstract:The objective of this work was to evaluate the adaptation marginal of restoring ceramic total crowns using system IPS 2 Empress and the Ceramcap system at two moments: after confections of copings and after applications of covering ceramics. However, ten stainless steel trunnions, had been tilted producing circular prepare that simulated the dental prepares with line of termination in shoulder of 1, 5 mm, axial walls in 6 degrees of oclusal convergence, rounded off angles to pulpar-axio and occlusal-axio, height of 7 mm, diameter in the base of the 11 preparation of mm and diameter in the oclusal of the preparation of 7, 06 mm. Boxes or concavities had been prevented. After that, they had been molded with silicona of addition and confectioned copings, as recommendations of the manufacturers. The evaluation of the adaptation marginal was made with an optic microscope of visible light with increase of 100 x, connected to system of image collection, had been made 4 images for each body-oftest, was used a software Imagelab 2000 for analysis of the images, where 12 points of mismatch for each image had been collected. The 148 values of mismatch marginal had been analyzed through test T student with level of significance of 5%. For system ceramic IPS 2 Empress and Ceramcap they had been found average of mismatch respectively of (86,1μm and 99,8μm) for copings and of (84,5μm and 97,9 μm), after applied covering ceramics. It had difference significant statistics enters the confection of copings after and the applications of covering ceramics, between the two studied materials. In comparison to the two studied systems, system IPS Empress presented average minors of mismatch...(Complete abstract electronic access below) / Orientador: José Roberto Cyry Saad / Doutor

Nas últimas três décadas houve incremento da exigência estética na área odontológica, provocado pela crescente valorização da apresentação pessoal, acompanhada do grande avanço tecnológico dos materiais em suas propriedades físicas e biológicas, o que proporcionou uma utilização clínica cada vez maior. Dentre esses materiais destacam-se as porcelanas odontológicas que vem apresentando excelentes resultados estéticos, sendo empregadas em diferentes situações clinicas. Durante a confecção de restaurações parciais tipo inlay e onlay com porcelanas feldspáticas, o clinico se depara com certos obstáculos. Um deles é o ajuste oclusal da peça protética que, nessas situações, deve ser realizado apenas após a cimentação definitiva, para evitar fraturas ou trincas. Com isso perde-se em algumas regiões o glaze, previamente realizado pelo técnico de laboratório. Isto pode acarretar alterações em sua estrutura com conseqüente aparecimento de trincas, perda de caracterização superficial, redução da resistência, geração de maior tensão durante contatos oclusais e alteração da sua rugosidade superficial. Esta última influenciará decisivamente na aderência bacteriana, acúmulo de biofilme dental, grau de desgaste do elemento antagonista e eficiência mastigatória. O trabalho avaliou in vitro a rugosidade (parâmetro Ra) de uma porcelana feldspática modificada glazeada e submetida a dois sistemas de acabamento e polimento. Os resultados não mostraram diferença estatisticamente significante entre os grupos e a superfície glazeada (P<0,05). / In the last three decades it had an increment of the aesthetic requirement in dentistry area, which became from the increasing valuation of the personal presentation, followed by the great technological advance of the materials in its physical and biological properties, which provided more clinical utilities over the time. Among these materials, the dental porcelains are showing excellent aesthetic results and they are used in different clinical practice situations. During the confection of partial restorations, like feldspathic inlay and onlay, the dentist comes across with certain obstacles. One of them it is the oclusal adjustment of the prosthetic restoration, which on these situations must be done through after the cimentation, to prevent fracture or crack lines. Therefore the glaze is lost in some regions, previously executed by the lab technician. It will be able to cause alterations in its structure and then it will show up same cracks, loss of superficial characterizations, reduction of the resistance, appearence of tension during oclusals contacts and alteration of its surface roughness. The last refer will influence decisively in the bacterial aderance, dental accumulation of biofilm, waste levels of antagonist surface and mastigatory efficience. The present study evaluated in vitro the roughness (Ra parameter) of the modified feldspathic porcelain glazed and submitted to two systems of finishing and intrabucal polishing. The results had not shown estatisticlly significant difference between the tests groups and the control glazing surface group(P<0,05).

M.S.

The effects of using different ball clays on the physical properties of the standard body have been shown. Although variations in all of the physical properties can be attributed to the use of different ball clays, these variations are more pronounced on the compressive strength properties. Since feldspar mainly controls fired shrinkage and fired absorption, and since the same amount of feldspar was used in each body, the effects of using different ball clays on these physical properties were not so pronounced. / Master of Science