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AbstractAbstract
[en] The interest for the use of ceramic materials for dental applications started due to the good aesthetic appearance promoted by the similarity to natural teeth. However, the fragility of traditional ceramics was a limitation for their use in stress conditions. The development of alumina and zirconia based materials, that associate aesthetic results, biocompatibility and good mechanical behaviour, makes possible the employment of ceramics for fabrication of dental restorations. The incorporation of vitreous phase in these ceramics is an alternative to minimize the ceramic retraction and to improve the adhesion to resin-based cements, necessary for the union of ceramic frameworks to the remaining dental structure. In the dentistry field, alumina and zirconia ceramic infiltrated with glassy phase are represented commercially by the In-Ceram systems. Considering that the improvement of powder's synthesis routes and of techniques of ceramic processing contributes for good performance of these materials, the goal of the present work is the study of processing conditions of alumina and/or 3 mol% yttria-stabilized zirconia ceramics infiltrated with aluminum borosilicate lanthanum glass. The powders, synthesized by hydroxide coprecipitation route, were pressed by uniaxial compaction and pre-sintered at temperature range between 950 and 1650 degree C in order to obtain porous ceramics bodies. Vitreous phase incorporation was performed by impregnation of aluminum borosilicate lanthanum powder, also prepared in this work, followed by heat treatment between 1200 and 1400 degree C .Ceramic powders were characterized by thermogravimetry, X-ray diffraction, scanning and transmission electron microscopy, gaseous adsorption (BET) and laser diffraction. Sinterability of alumina and /or stabilized zirconia green pellets was evaluated by dilatometry. Pre-sintered ceramics were characterized by apparent density measurements (Archimedes method), X-ray diffraction and scanning electron microscopy. Vickers impression tests and cytotoxicity essays were performed after glass phase incorporation. Considering the structural integrity of samples, homogeneity of microstructures, high fracture toughness values (3.6 - 4.9 MPa.m1/2) and no cytotoxicity effects, it was verified that alumina based ceramics, prepared from coprecipitated powders, are adequate for production of dental frameworks infiltrated by vitreous phase. (author)
Original Title
Sintese e processamento de compositos a base de alumina e zirconia com infiltracao de fase vitrea para aplicacoes odontologicas
Primary Subject
Source
2009; 118 p; Diss. (M.Sc.)
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation; Numerical Data
Report Number
Country of publication
ALUMINIUM COMPOUNDS, BUILDING MATERIALS, CHALCOGENIDES, CHEMICAL ANALYSIS, COHERENT SCATTERING, DATA, DIFFRACTION, ELECTRON MICROSCOPY, ELEMENTS, FABRICATION, GRAVIMETRIC ANALYSIS, INFORMATION, MATERIALS, METALS, MICROSCOPY, NUMERICAL DATA, OXIDES, OXYGEN COMPOUNDS, QUANTITATIVE CHEMICAL ANALYSIS, RARE EARTHS, SCATTERING, THERMAL ANALYSIS, TRANSITION ELEMENT COMPOUNDS, YTTRIUM COMPOUNDS, ZIRCONIUM COMPOUNDS
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