Comparison of color stability of two resin composites in blood area

Color change of composite restorations in different color media over time is a common problem in esthetic dentistry, creating the need to replace the restoration and spending a great deal of cost and time by patients. The aim of this study is in vitro comparison of color stability of resin composites in blood area.
Fifteen disk-shaped specimens of each resin composite (valux plus and filtek supreme) were prepared. The samples were kept in distinct water containers for 24 h in order for the primary water absorption to happen by restorative materials. Then, for 1 month, they were immersed in blood every day for 20 min. The color values (L*, a*, and b*) were measured using the CIE L*a*b* system. The color change values were calculated before and after 1, 7, and 30 days of immersion. The amounts of ΔE1, ΔE7, ΔE30 for each group were calculated with ΔE = [(ΔL*)2  (Δa*)2 (Δb*)2]½. Repeated measures and paired t-tests and one-way analysis of variance (ANOVA) were applied for the statistical analysis.
The discoloration in two groups was not significant and visually perceptible. However, microhybrid samples at primary time (less than 7 days), under the significant level, showed more discoloration, but nanofilled’s samples discoloration increased till the 30th day.
Blood as a biological agent that contains globulin as a large molecule, did not have a significant impact on changing the color of the resin composite.