Understanding the factors that affect tooth shade selection will help the dentist to make the appropriate choice. The purpose of this Clinical Update is to discuss those factors that influence color and matching tooth shade, and the steps the clinician may take to more consistently match the restorative material with the shade of the tooth. In order to select a tooth shade, one must first understand how color is defined. Hue is the quality by which we distinguish one color family from another, such as red from yellow, green from blue or purple. Chroma is the intensity or the saturation of hue found in a color.
Value is the lightness or darkness of a color.
Metamerism is when two objects with differing spectral curves match under a given illuminant. An example of this is a restoration that matches the tooth or adjacent teeth in the dental operatory, but when viewed in a different lighting condition, the restoration no longer matches. Color constancy refers to the apparent color change exhibited by a single color when the spectral distribution of the light source is changed or when the angle of illumination or viewing is changed. Each of these factors has its own variables, which if changed, the perception of color changes also. Many persons have some sort of color blindness, often a red-green deficiency.