Resumo

MARQUES, Vanessa Fontenele et al. Evaluating Knoop microhardness and diametral tensile strength of composite resins of direct use. RFO UPF [online]. 2014, vol.19, n.2, pp. 200-204. ISSN 1413-4012.

The mechanical properties of dental composites can provide important information on their probable clinical performance. Objective: in this perspective, this article aims to evaluate both microhardness and the diametral tensile strength of composite resins of direct use. Materials and method: four composite resins were evaluated: Filtek Z-250^® (3M ESPE, Sumaré, São Paulo, Brazil), Filtek Z-350 XT^® (3M ESPE, Sumaré, São Paulo, Brazil), Filtek P-90^® (3M ESPE, Sumaré, São Paulo, Brazil) and Opallis^® (FGM, Joinville, Santa Catarina, Brazil). Forty cylindrical specimens were prepared (n=10) whose measures were 4mm in diameter and 2mm in height. After preparation, the samples were stored in artificial saliva for 24 hours and then polished and subjected to mechanical tests. A Knoop indenter was used for the hardness test with a load of 50g for 5 seconds at the top and bottom surfaces. After measuring the hardness, the samples were subjected to diametral tensile strength test. The resulting data were analyzed by ANOVA and the Tukey test (α = 0.05). Results: the results obtained were as follows: The Z-250^® and Z-350 XT composites showed higher hardness values without statistical difference between them. There was no difference between P-90^® and Opallis^®. In diametrical tensile strength test, Z-250^® presented higher values than P-90^® and Opallis^®. Conclusion: based on these results, we conclude that Z-250^® and Z-350 XT^® composites showed better mechanical properties than P-90^® and Opallis^®.

Palavras-chave : Composite resins.; Hardness.; Tensile strength..