Influence of Radiation on Properties of Resinous Materials

Objective: the aim of this study was to evaluate the influence of Cobalt60 gamma radiation on the mechanical properties of polymeric materials. Methods: Three restorative materials (3M-Espe) were evaluated: RC, composite resin Z100; RL, laboratory resin Sinfony; CR, resin cement RelyX ARC. Using the flexural strength test of four points, diametral tensile strength and knoop hardness as parameters, fifteen samples per test were divided into three groups (n = 5): C control group not irradiated; G60Gy gamma-Co60 sixty Gy single dose; G2Gy gamma-Co60 sixty Gy daily dose split in two Gy. Data were analyzed by ANOVA and Tukey test (α = 0.05). Results: The radiation did not influence the flexural strength values for the RL, but reduced the values for the other two materials. Values obtained for diametral tensile test were similar to RL. The knoop hardness to RC was not affected by irradiation, while RL and CR were influenced by Cobalt60 gamma radiation. Conclusion: The use of irradiation as a single dose testing polymeric restorative materials, result in different changes from those seen with fractionated dose. The irradiation in divided doses negatively influences the mechanical properties of Z100 resin and resin cement RelyX ARC.