Variation in instrument-based color coordinates of esthetic restorative materials by measurement method—A review

Objectives Optical properties of an object are determined visually or instrumentally. Although instrumental measurement provides objective and quantitative color coordinates, these values vary by the measurement method such as specimen and background conditions, instrument settings and illuminant. The objective of this study was to review the influence of the measurement method on the instrumental color coordinates of esthetic dental restorative materials. Methods Published reports on the measurement method dependent color variations of esthetic restorative materials were reviewed. Results Surface roughness influences the color coordinates differently by the surface roughness range and the measurement geometry. Specimen thickness and the kind of illuminant influence the color coordinates, and the influence of background varied by specimen thickness. Therefore, the specular component excluded (SCE) geometry that reflects the surface condition of specimens is suggested as the correct measurement geometry. Surface roughness, thickness and layering of specimens, and the kind of illuminant should be stipulated in each measurement. There should be a standard for the color and gloss of the background. Significance Variables in instrumental color measurements should be stipulated to obtain consistent and comparable color coordinates, and a general guideline for instrumental color measurement of dental materials should be established.