Physical Properties of Teeth

An object (a tooth) can alter the color of light.³⁹ When the object (tooth) reflects specific wavelengths of visible light, the color appears.³⁹ The color and the final appearance of the teeth are not only affected by the hue, value, and chroma but also the surface texture and various other optical properties associated with teeth such as translucency, opacity, opalescence, and fluorescence.^4,7,11 Dental restorations must be fabricated such that not only their color but also their surface texture and optical properties are similar to natural teeth.

Surface texture

Surface texture represents the minute details and irregularities present on the surface of teeth.⁴ Natural teeth have various characteristics such as lobes, stippling, striations, and ridges (Fig. 10).^4,7 Teeth have a very rough surface texture when they erupt in the oral cavity.⁴ However, with time the tooth surfaces wear and become smooth.⁴ The surface of a tooth may be categorized as having a heavy, medium, or light texture.⁴ Surface texture affects the appearance of a tooth by influencing the quantity and path of light reflected off its surface.^4,7 A rough or heavy surface texture is associated with a lower value (dull appearance) because it tends to scatter the reflected light in several directions.⁴ A light surface texture has a higher value (dynamic appearance) due to more uniform light reflection and a greater amount of light returning to the viewer’s eye.⁴

Fig. 10 - Striations, ridges, and lobes are seen on the facial surface of the central incisors.

Fig. 10 - Striations, ridges, and lobes are seen on the facial surface of the central incisors.

Surface gloss

Surface gloss also affects the appearance of teeth.⁷ High gloss surfaces can create mirror-like reflections of light resulting in the surface appearing brighter and more vivid.⁴ Low-gloss or matte surfaces result in diffuse scattering of light, making the surface and its color appear duller.⁴ Restorative materials must be finished to match the surface texture and gloss of adjacent natural teeth.⁴¹ Surface texture and gloss discrepancies may result in esthetic failure even if the base colors are perfectly matched.