Use of a porcelain color discrimination test to evaluate color difference formulas

A. G. Wee, D. T. Lindsey, K. M. Shroyer, W. M. Johnston

Research output: Contribution to journalArticlepeer-review

Abstract

Statement of the Problem: Limited studies have indicated that an alternative small color difference formula would be more appropriate for use in dentistry. Purpose: The purposes of this study were to determine which color difference formula provides a superior degree of fit for judgments of perceptibility and acceptability and to determine whether different groups of evaluators have different levels of perceptibility and acceptability for each color difference formula. Materials and Methods: Each observer from four groups (four dentists, four dental assistants, four technicians, and four patients) made independent observations of perceptibility and acceptability on pairs of opaque porcelain disks (14-mm diameter 3-mm thickness). Color differences of the pairs were calculated using ΔE*(ab), ΔE (CMC)(l : c), and ΔE (2000) color difference formulas. The observer judgments were regressed to each color difference independently for perceptibility and acceptability. The area under the receiver operator curves was calculated and ranked, and the optimal factor for the Color Measurement Committee (CMC; Society of Dyers and Colorists, Great Britain) color difference formula was chosen. A repeated measures maximum likelihood analysis of variance (ANOVA) was applied to determine the statistical significance of fit between the observer groups and the various color difference formulas for both perceptibility and acceptability. Results: A difference in the degree of fit of the judgments of color differences was found for the three formulas and the two judgment types studied, with no significant interaction. There was a lower degree of fit for the DE*(ab) formula than for ΔE (CMC)(2 : 3) and ΔE (2000) formulas. No significant difference was found in the mean judgment levels between the observer groups studied, nor with any interaction. Conclusions: The ΔE (2000) and ΔE (CMC)(2 : 3) color difference formulas provide a better fit to the calculated color differences, therefore providing better indicators of human perceptibility and acceptability of color differences between tooth colors.

Original languageEnglish (US)
Pages (from-to)135-136
Number of pages2
JournalJournal of Esthetic and Restorative Dentistry
Volume21
Issue number2
StatePublished - Apr 2009
Externally publishedYes

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