Staining of the specimens resulted in a more perceivable color change. In addition, mean ΔE2 values were higher in the DF subgroups compared to the TPH3, with the difference significant only in shade A4 (P=0.001) (Table 2). In shade A2, specimens previously bleached with LumaWhite-Plus showed significantly higher staining (P=0.025) compared to the other two bleaching systems (Table 3). Values for ΔE for after staining are preceded with a negative sign to indicate that the color change was to a darker shade.