Three-dimensional color coordinates of natural teeth compared with three shade guides.

The three-dimensional color coordinates of 2832 human teeth were measured in vivo and were plotted in a cylindrical Hue, Value/Chroma space, using a program in BASIC. The commonly used Vita, and Bioform shade guides, and a surviving shade guide of E. B. Clark were compared with these natural teeth. The shade guides did not match well with the color space of the human teeth, and the anticipated deficiencies were in the yellow-red Hues, higher Values, and higher Chromas. However, the points for natural teeth were in a narrow flounder-like configuration, suggesting that a representative shade guide matching natural teeth could be generated with limited samples.