Surface Roughness and Color Change of Gamma Irradiated Nanohybrid Resin Composite and Giomer Restorative Materials

Abstract Background This study evaluated the effect of gamma radiation on surface roughness and color change of nanohybrid composite and giomer restorative materials. Methods Twenty-four-disc shaped specimens (2×2mm) were fabricated; half of them were prepared from Filtek Z-350 nanocomposite while the other half were prepared from Beautiful II giomer restorative material. Each material was divided into two subgroups, control and gamma irradiated. Surface roughness was assessed for each group after 24 hrs. then after 6 months storage in artificial saliva using USB Digital microscope while color change was evaluated using a Reflective spectrophotometer at the same time intervals. Data showed parametric distribution and were analyzed using independent and paired t-test for analyzing independent and dependent variables respectively. Intergroup comparisons were analyzed using one-way ANOVA followed by Tukey’s post hoc test. Results For surface roughness, there was significant increase for both nanocomposite and giomer after 6 months storage. For color change assessments, at both time intervals, Giomer had significantly higher color change than composite (p < 0.05). For both materials, color change measured after 6 months was significantly higher than 24 hours value (p < 0.05). Exposure to gamma irradiation did not affect surface roughness of both materials while it affected their color change. Conclusions Time has a detrimental effect on surface roughness of resin composite and Giomer, while gamma radiation has the same effect but on the color change.