Reflectance spectra of natural and acrylic resin teeth

A method has been described for determining the reflectance spectra of teeth at various parts of the tooth surface. The shape and size of the teeth were accounted for by appropriate experimental and mathematical techniques. In all instances where a subtle difference in tooth color was discernible, this difference was also apparent on the corresponding spectra. The spectra of acrylic resin teeth showed characteristic absorption shoulders caused by pigmentation. These shoulders did not appear in the spectra of natural teeth where the reflectivity gradually increased with increasing wavelength. Differences were observed in the colors as well as the spectra of teeth from different shade guides which were marked with the same shade number by the manufacturer. The method may be applied for control of the color quality of artificial teeth as well as the selection of pigments in order to obtain an appropriate shade range and to reduce effects of metamerism.