Lightness, chroma, and hue distributions of a shade guide as measured by a spectroradiometer.
BACKGROUND
The color attributes of commercially available shade guides have been measured by spectrophotometers (SP), which are designed to measure flat surfaces. However, there is limited information on the color distribution of shade guides as measured by spectroradiometers (SR), which are capable of measuring the color of curved surfaces.


OBJECTIVE
The purpose of this study was to determine the distributions of lightness (CIE L*) and chroma (C*(ab)) step intervals between adjacent shade tabs of a shade guide based on the lightness, chroma, and hue attributes measured by an SR.


METHODS
Lightness, chroma, hue angle, and CIE a* and b* values of the shade tabs (n=26) from a shade guide (Vitapan 3D-Master) were measured by an SR under daylight conditions. The distributions of the ratios in lightness and chroma of each tab compared with the lowest lightness tab or the lowest chroma tab were determined. The values for each color parameter were analyzed by a 3-way ANOVA with the factors of lightness, chroma, and hue designations of the shade tabs (alpha=.05).


RESULTS
The chroma and CIE a* and b* values were influenced by the lightness, chroma, and hue designations of the shade tabs (P<.001); however, the lightness and hue angle were influenced by the lightness and hue designations, but not by the chroma designation. Distributions for the CIE a* and b* values, in each lightness group, corresponded with the chroma designation. However, the intervals in the lightness and chroma scales between adjacent tabs were not uniform.


CONCLUSIONS
The intervals in the color parameters between adjacent shade tabs were not uniform based on SR measurements. Therefore, a shade guide in which shade tabs are more equally spaced by the color attributes, based on the values as measured by an SR along with observers' responses with respect to the equality of the intervals, should be devised.
Lee
Yong-Keun
YK
Denforus Co, Seoul, Korea. ykleedm@gmail.com
Yu
Bin
B
Lim
Ho-Nam
HN
D000704:Analysis of Variance; D003116:Color / Q000592:standards*; D003124:Colorimetry / Q000379:methods*; D017267:Dental Prosthesis Design; D008027:Light; D017797:Prosthesis Coloring; D011874:Radiometry / Q000379:methods; D012015:Reference Standards