Abstract: A probe, for use with a spectrophotometer, which senses the reflectance of a sample remote from the spectrophotometer. The probe includes a housing having a probe portion positionable proximate the sample, and an integrating chamber disposed within the probe housing and having a radiation input port, a sample port for passing diffused radiation to the sample and returning reflected radiation from the sample, a reference port, and an exit port to receive radiation reflected from the sample through the sample port. The probe further includes a guide for directing radiation to the radiation input port from a radiation source, and an element, responsive to the exit port and the reference port, for selectively conveying reflected radiation from the sample and the wall of the integrating chamber in the probe to the remote spectrophotometer.

Abstract: Polychromatic light is directed at the surface of a live tooth and color data of light reflected therefrom is recorded, multiplied by the stored power distribution of a first standard illuminant and converted to three tristimulus values. Such values are compared with color values of a first group of stored color dental shades, and if a match occurs within a given tolerance, an indication of the nature of the recipe is produced. A second level search may be carried out against a substantially larger group of stored dental shades in the event of a no-match condition resulting from the first search. Excellent lifelike reproduction of the patient's tooth is enhanced by checking for least metamerism by operating upon the measured data with other illumination standards and selecting the best match under all lighting conditions.