Color Shade Variation of Universal Resin Composite

Objectives: A universal shade bulk-fill resin composite has been developed. Resin blocks with different shades were prepared as background colors, and various resin composite (CR) samples were layered on top. Color measurements were then conducted to compare and analyze the color shade variation.
Methods: The materials used in the experiment were OMNICHROMA FLOW BULK (OFB), OMNICHROMA FLOW (OF), 3M Filtek™ Fill and Core Flowable Restorative (FCU), Beautiful Unishade Flow (BU), Clearfil Majesty ES Flow (A2, MJ), and BEAUTIFIL Flow Plus X (A2, BF). Each CR material was filled into a Teflon mold (diameter 10mm, height 1mm) to produce disc-shaped samples. Resin composite blocks of ESTELITE Σ Quick (A1–A4, C3) were prepared as background colors. The color of the CR blocks and the color of the CR samples placed on the CR blocks with glycerin were measured using a digital colorimeter (SE7700), and the color difference (ΔE*ab, n=10) was calculated. The data were evaluated using one-way analysis of variance (ANOVA) and Welch's t-test (Bonferroni correction, α= 0.05).
Results: The ΔE*ab values of OFB and OF were below 6 for all groups, whereas FCU showed nearly the same values across all groups. For BU, MJ, and BF, the color difference increased as the shade became darker, suggesting that the background color influenced the results. Significant differences in color difference were observed between the low ΔE*ab groups and some of the FCU, BU, MJ, and BF groups (p<0.05). Additionally, no significant differences were found between the OFB and OF groups, or between the FCU and BU groups.
Conclusions: It was suggested that OMNICHROMA FLOW BULK and OMNICHROMA FLOW exhibited different behavior compared to other CR materials in response to background colors with different shades.