Effect of the curing methods on the surface hardness of different thickness on heat–cured acrylic resin

Aims : to evaluate the surface hardness of the heat–cured acrylic resins with two different thicknesses cured by two curing methods conventional water bath and microwave energy. Materials and Methods : Heat–cured acrylic resin was used in this study. Rectangular specimens were prepared with two different thicknesses (3 and 6 mm) and cured by two different curing methods, conventional water bath and microwave energy methods. The specimens were divided into two groups according to the curing method and specimen's thickness. Forty specimens were prepared, ten specimens for each group. The surface hardness was evaluated with Rock well hardness tester. Mean values wear compared statistically with one way analysis of variance (ANOVA) followed by Duncan's multiple range test to determine the significant different among the groups at (p < 0.05) level of significance. Results : the results showed that there is a highly significant difference of the means value of the surface hardness among the four tested groups. Specimens cured by conventional water bath with 3 mm thickness have the highest value in relation to 6mm thickness of specimens cured by microwave energy. Conclusions : the curing method, and specimens thicknesses have a significant effect on the specimens surface hardness value. The specimens that cured by the conventional water bath method have a higher values than that cured by the microwave energy curing method and the thicker specimens have a lower values than the thinner one in both curing methods.