Journal of Dental Research, Vol 69, 1762-1764, Copyright © 1990 by International & American Associations for Dental Research Online Journals
A new, small-color-difference equation for dental shades
W. J. O'Brien, C. L. Groh and K. M. Boenke
Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor 48109-1078.
Traditionally, dental-shade-guide standards are designated in terms of
Munsell hue (H), value (V), and chroma (C). However, delta E color
differences proposed as ADA tolerances for shade guides are in the CIE
L*a*b* system. The purpose of this study was to evaluate a new
color-difference equation, delta EM = C delta H/5 + 7 delta V + 4 delta C
for estimation of small color differences by Munsell parameters. The
published values of the Bioform shade-guide tooth colors determined with a
Beckman spectrophotometer were used. Color differences among 276
combinations of the 24 Bioform shade-guide colors were calculated with Eq.
1, with use of the Munsell notation, and also with the CIE L*a*b* equation
for delta E. An estimate of the accuracy of Eq. 1 was 0.41 delta E units
when delta E CIE was below 4.0. The Vita shade-guide colors were determined
with a Beckman spectrophotometer. This data set contained 16 samples, and
120 combinations were used for calculation of color difference. An estimate
of the accuracy for this set of data was 0.35 delta E units when delta E
CIE was less than 4.0. The new color-difference equation provides a means
for estimation of delta E CIE L*a*b* color difference between dental shades
with Munsell notation. This equation will be useful for estimation of small
delta E CIE L*a*b* values for shade-guide teeth that are designated in
terms of Munsell notation.
