Resistência à flexão de porcelanas feldspáticas convencionais processadas por injeção
Flexural strength of heat-pressing feldspathic porcelains
Oliva, Eduardo Andrade de; Chaves, Carolina de Andrade Lima; Medeiros, Flávia Regina Machado de; Cruz, Carlos Alberto dos Santos
Rev. odontol. UNESP, vol.38, n5, p.318-323, 2009
Resumo
O objetivo deste estudo foi investigar o efeito do processamento por injeção (método da cera perdida) na resistência à flexão, em três pontos, de porcelanas feldspáticas convencionalmente obtidas por sinterização. Foram avaliadas as porcelanas Ceramco-2, Duceragold, Duceram-Plus, Excelsior, Omega-900, Symbio, Vitadur-Alpha e VMK-95. Como controle, foi também utilizada a porcelana Cergogold, fornecida na forma de pastilhas pré-sinterizadas e processada exclusivamente por injeção. Corpos de prova em forma de barra (n = 10), com dimensões de 25 × 5 × 2 mm (ISO-6872), foram confeccionados em matrizes metálicas e processados, por sinterização ou injeção, nas temperaturas de cocção indicadas pelos fabricantes. Os ensaios foram realizados em equipamento MTS-810 (Material Test System, EUA), com célula de carga de 10 kN e velocidade de 0,5 mm.min–1. Os resultados, submetidos à análise de variância (p ≤ 0,05), mostraram que o processamento por injeção foi capaz de proporcionar maior resistência à flexão para as porcelanas Duceram-Plus, Excelsior, Omega-900, Symbio e VMK-95 (p < 0,001). Nessa mesma condição experimental, a porcelana Cergogold mostrou-se estatisticamente superior apenas à porcelana Vitadur-Alpha, sendo inferior à porcelana Omega-900 e semelhante às demais (p < 0,001). A resistência à flexão das porcelanas Ceramco-2, Duceragold e Vitadur-Alpha não foi influenciada pelo processo de obtenção (p < 0,001).
Palavras-chave
Porcelana dentária, métodos de processamento, resistência à flexão
Abstract
The aim of this study was to evaluate the effect of injection process, on the three-point flexural strength on feldspathic ceramic, fabricated by sintering technique. The ceramics evaluated were Duceragold, Duceram Plus, Excelsior, Omega 900, Symbio,Vitadur Alpha, VMK 95 and Ceramco 2. Cergogold, that the processing technique is based on a conventional injection moulding, was used for control. The bar-shaped specimens (n = 10) with the size of 25 × 5 × 2 mm (ISO-6872) were fabricated in a metal mould and processed by injection or sinterized, according to manufacturing specifications. The flexural test was performed in a MTS 810 testing machine (Material Test System, USA), with a 10 kN load cell and a crosshead speed of 0.05 mm.min–1. The data (MPa) were subjected to analysis of variance (p ≤ 0.05), and showed that the injection processed enhance the flexural strength of Duceram-Plus, Excelsior, Omega-900, Symbio and VMK-95 (p < 0.001). In this experimental condition, the ceramic Cergogold showed high value than Vitadur-Alpha, was inferior to the ceramic Omega-900, but there were no significant difference with the others (p < 0.001). The flexural strength was not influenced by the processing method for the ceramics Ceramco-2, Duceragold and Vitadur-Alpha.
Keywords
Dental ceramic, processed method, flexural strength
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