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Pesquisa Científica

v. 24 n. 68 (2015): ROBRAC

Effect of irradiation on the mechanical behavior of restorative materials

fevereiro 9, 2015
fevereiro 10, 2015


Purpose: This study evaluated the influence of cobalt-60 gamma irradiation on mechanical properties of restorative materials. Material and Methods: Two glass ionomer cement (Ketac Molar and RelyX Luting), a composite resin (Filtek Z350) and two feldspathic ceramics (VITA VMK-95 and StarLight) were evaluated. The samples were made in accordance with the ISO normative for the four-point bending test (n = 20), diametral tensile (n = 20) and microhardness tests; Knoop hardness (KHN) for glass ionomer and composite, and Vickers hardness (VHN) for ceramics (n = 10). The samples were divided into two groups: irradiated (Ir), subjected to cobalt-60 gamma irradiation in a similar protocol used for patients with head and neck tumor; and control group (C), samples not subjected to the irradiation protocol. Results: Data were analyzed using one-way ANOVA, for diametral tensile and four-point bending test, and two-way ANOVA followed by the Tukey’s HSD test (α=.05), for Knoop and Vickers microhardness. Gamma irradiation significantly reduced the diametral tensile strength only for Ketac Molar (P<.001). Composite resin presented flexural strength values significantly decreased when submitted to the radiotherapy (P<.003). For all materials tested, the microhardness was not influenced by the region (top and bottom). Irradiation increased the KHN values for Ketac Molar (P<.000) and decreased for the RelyX Luting 2 (P<.002). The VHN was not influenced by the irradiation. Conclusions: Gamma irradiation therapy influenced the mechanical properties of the glass ionomers and the composite resin, although not alters any ceramic properties.