Influência da variação da intensidade de luz, para uma mesma exposição radiante, no comportamento mecânico de uma resina convencional e de uma resina de baixa contração

• Ano de defesa: 2012
• Autor(a) principal: Gonzalez, Mariana Rodrigues
• Orientador(a): Perez, Cesar dos Reis
• Banca de defesa: Miranda, Mauro Sayão de , Dias, Katia Regina Hostilio Cervantes , Poskus, Laiza Tatiana
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Odontologia
• Departamento: Centro Biomédico::Faculdade de Odontologia
• País: BR
• Palavras-chave em Português: Resinas dentárias; Testes de dureza; Resinas compostas; Polimerização; Dureza; Resistência à tração
• Palavras-chave em Inglês: Composite resins; Polymerization; Hardness; Tensile Strength
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/14141

This study has the purpose of evaluating the variation of the intensity of light, for a constant radiation exposure, for flexural strength, for microhardness, and for tensile strength, of a conventional composite and a low shrinkage composite. The test samples were made of Filtek Z250 (3M ESPE) e Filtek P90 LS (3M ESPE) light-activated composites. The following light activating protocol was used: conventional (400mW/cm² for 60 s); medium intensity (700mW/cm² for 34 s), and high intensity (950mW/cm² for 26 s). All of the test samples received the same radiation exposure of 24J/cm². The flexural strength was measured through the three-point bending test. For this test, thirty especimens were made for each material (n=10), measuring 10mm x 2mm x 1mm. The Knoop hardness evaluation was carried out using six discs of each composite measuring 5mm in diameter, and 2mm in height (n=2), with five indentations in each specimen. Thirty cylindrical test samples of each composite (n=10) measuring 3mm in diameter, and 6mm in height were obtained for the diametral tensile test. The statistical analysis of the results was carried out through analysis of variance test (ANOVA) and through Tukey s multiple comparisons test (p < 0.05). The P90 composite flexural strength was not significantly influenced by the different activating methods, while Z250 achieved significantly higher values for the high intensity protocol when compared to the conventional one. For all light intensities, the Z250 results were higher than those for P90. P90's microhardness was statistically higher for the medium intensity group when compared to the others, whereas Z250's results had no statistical difference for the different activating protocols. For the same irradiation, Z250 presented higher values for microhardness than P90, except for the medium intensity protocol, which had no statistical difference between the different materials. The tensile strength values were not significantly influenced neither by the different light intensities, nor by the materials. The influence of the variation of light intensity depends upon the type of composite, as well as the mechanical property to be evaluated.