Objectives . The aim of the study was to assess the correlation between the percentage of fillers and the colorimetric parameters of colored resin matrices used for dental composites.
Materials and methods . Six colored resin matrices (Herculite B1 Enamel, A3 Enamel, C4 Enamel, B1 Dentin, A3 Dentin, and C4 Dentin, provided by Kerr-Hawe company by incorporating the normal coloring pigments for the given shade into the neat resin) were mechanically mixed with various concentrations of a barium glass filler (0.7 μm mean particle size, provided by Kerr-Hawe company) in a DAC-150 mixer (Flacktek, Landrum, SC, USA). The experimental composites contained filler levels of 30, 35, 40, 45, 50, 55, 60, 65 and 70 wt%. Five one mm thick, disk-shaped samples were prepared for each experimental group by curing in a standard mold with a QTH light (Trilight Elipar- 3M/Espe) at 800 mW/cm 2 . Samples were stored for one week after the light curing at 37 °C in air before the colorimetric evaluation. One reading per sample was performed either on a white background or on a black background with a color guide (Byk Gardner): illuminant C, illuminating/viewing geometry 45°/0° and standard observer 2 degrees. 12 colorimetric parameters were measured: L*, a*, b*, C* (chroma), h° (hue), White Berger (WB) Index, Yellowness (YI) D1925 index. Linear correlations were calculated and R 2 data are given in the following table (data obtained either on a white-W- or on a black-B- background).