Light Scattering and Gloss of an Experimental Quartz-filled Composite

For samples of polymethylmethacrylate with and without quartz filler, the inverse of the contrast-gloss ratio is shown to be related to surface roughness and to the optical scattering coefficient. This finding adds to the importance of optical scattering, which has been widely studied because of its relation to color and translucency of materials. Furthermore, optical scattering by composite fillers is shown to be linearly related to the concentration of the filler material within the range of concentrations studied. Quartz fillers were incorporated at concentrations from 5 to 20 weight percent and were short fibers or granular powder, with the granular particles ranging in median equivalent spherical diameter from 15 to 3.3 μm. The efficiency of optical scattering for the granular quartz filler increased as the size of the filler decreased.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68026/2/10.1177_00220345860650060501.pd

The Color Accuracy of the Kubelka-Munk Theory for Various Colorants in Maxillofacial Prosthetic Material

The reflectance model developed by Kubelka and Munk was evaluated for agreement in color prediction of thick pigmented samples and for linearity of optical absorption and scattering coefficients with concentration of colorant in maxillofacial elastomer. The colorants tested were generic opacifiers, dry mineral earth pigments, and fibrous colorants. Significant linear relationships were commonly found between the optical coefficients and the concentration of the colorants. These relationships indicated occasional optical interaction between the colorants and the elastomer. Color differences between theoretical and observed colors of the thick samples averaged 2.96, 3.47, and 1.60 for the opacifiers, mineral earth pigments, and fibrous colorants, respectively, when measured using the CIELAB uniform-color space. The agreement between theoretical and observed colors was significantly closer for the fibrous colorants than for the dry mineral earth pigments of the same labeled color.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67968/2/10.1177_00220345870660090601.pd