Method: Optical characterizations of three dissimilar composite shades were separately accomplished by fitting reflectance of uniform layers to Kubelka-Munk reflectance theory. Two blending cylindrical specimens of each of three shades were first formed with a cavity ~2mm deep and 4mm diameter at the center, which was then filled separately with each dissimilar shade. Visible reflectance spectra were determined from the center in steps of 1mm radially, on each of black and white backings. Reflectance values were also calculated based on layering of the two shades and for each shade alone on each backing. Color differences from the outer shade alone to each measured and the other theoretical points were determined using CIEDE2000. The slope of color differences relative to radial distance of the central points were analyzed for dependence on the combination of shades and the backing. Reflectance differences from theoretical reflectance values of the outer shade alone at all wavelengths to the central points were analyzed for dependence on optical characterization of the inner shade and the backing.
Results: Changes in color within the center of the blending specimens were unique to the combination of the shades studied (P<0.001) and the magnitude of color differences were dependent on the backing (P<0.001). Color differences were found which exceeded the perceptibility threshold. Reflectance difference was found to depend on optical characterization (P<0.001) and backing (P<0.001).
Conclusion: This model using composite allows for identification of optical properties which promote blending when desirable for restorative purposes or enhance perception when desirable for health detection systems.