Use of a porcelain color discrimination test to evaluate color difference formulas.
BACKGROUND
Limited studies have indicated that an alternative small color difference formula would be more appropriate for use in dentistry.


OBJECTIVE
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 if different groups of evaluators have different levels of perceptibility and acceptability for each color difference formula.


METHODS
Each observer from 4 groups (4 dentists, 4 dental assistants, 4 technicians, and 4 patients)made independent observations of perceptibility and acceptability judgments on pairs of opaque porcelain (VitaOmega 900) disks (14 mm in diameter by 3 mm thick). Color differences of the pairs were calculated using DeltaE*(ab), DeltaE(CMC)(l:c), and DeltaE(2000) color difference formulas, and the observer judgments were regressed to each color difference in dependently for perceptibility and acceptability. The area under the receiver operator curves was calculated and ranked, and the optimal factor for the CMC (Colour Measurement Committee, Society of Dyers and Colourists, Great Britain) color difference formula was chosen. A repeated measures maximum likelihood ANOVA (alpha=.05) was applied to determine statistical significance of fit among the observer groups, and the various color difference formulas for both perceptibility and acceptability. Tukey-Kramer Adjustment (alpha=.05) was used as a post hoc test.


RESULTS
A difference in the degree of fit of the judgments of color differences was found for the 3 formulas (P=.001)and the 2 judgment types (P<.001) studied, with no significant interaction (P=.979). The Tukey-Kramer test identified a lower degree of fit for the DeltaE*(ab) formula compared to DeltaE(CMC)(2:3) and DeltaE(2000) formulas. No significant difference was found in the mean judgment levels among the observer groups (P=.474) studied, nor within any interaction (P>.404).


CONCLUSIONS
DeltaE(2000) and DeltaE(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.
Wee
Alvin G
AG
Division of Oral Facial Prosthetics / Dental Oncology, Department of Otolaryngology, University of Nebraska Medical Center, Omaha, Nebraska 68198-1225, USA. awee@unmc.edu
Lindsey
Delwin T
DT
Shroyer
Kathryn M
KM
Johnston
William M
WM
D000704:Analysis of Variance; D003116:Color; D003118:Color Perception; D003124:Colorimetry / Q000379:methods*; D003776:Dental Porcelain / Q000737:chemistry*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D012372:ROC Curve; D012684:Sensory Thresholds
D003776:Dental Porcelain
J Dent Res. 1989 May;68(5):819-22
2715476
Dent Mater. 1987 Oct;3(5):246-51
3479360
Quintessence Int. 1985 Jan;16(1):47-58
3883392
J Prosthet Dent. 1981 May;45(5):499-501
7012316
J Prosthet Dent. 2000 Apr;83(4):396-401
10756288
J Prosthet Dent. 2007 Jan;97(1):45-53
17280891
J Dent Res. 1989 Dec;68(12):1760-4
2600257
Phys Med Biol. 1994 Jul;39(7):1133-42
15552102
Int J Prosthodont. 1999 Mar-Apr;12(2):135-9
10371915
J Prosthet Dent. 1999 Mar;81(3):277-84
10050114
J Dent. 1998 Sep;26(7):547-54
9754742
Int J Prosthodont. 1998 May-Jun;11(3):246-54
9728119
Int J Prosthodont. 1998 May-Jun;11(3):224-32
9728116
Dent Mater. 2005 Jul;21(7):665-70
15978276