Objective: To compare the ranking of chromameter CIELAB measurements to that of value-based Bioform color ordered shade. Methods: A new set of Bioform Color Ordered Shade guide was measured for L*, a* and b* parameters using a Minolta CR-321 Chroma Meter by two investigators independently. The aperture (Ø 3mm) of the chromameter measuring head was positioned at the center of each shade tab, and three measurements were made with repositioning the aperture for each measurement. The differences in average measurements (delta L*a*b*) and the delta E were calculated. The intra- and inter-investigator consistency of the measurements was evaluated using the Kruskal-Wallis One-Way Analysis of Variance on Ranks and Mann-Whitney Rank Sum Test, respectively. Spearman Rank Order Correlation test was used to examine the relationship between the numerical Bioform shade score and the corresponding L*, a* and b* values. Results: There were no significant differences among the intra- and inter-investigator measurements (p>0.28). ). While the correlations between the chromameter measurements and the value-based Bioform shade ranking were significant (p=0.01); only two L*, five a* and three b* values matched the value-based Bioform shade ranking. Compared to the Bioform, deviations of the L* values varied greatly from 1 to 20 rankings. The B85 and B62 varied 20 and 15 rankings, respectively. Less than 50% of the Bioform tabs deviated less than 3 rankings. The delta Es for one-shade differences ranged from 0.62 to 9.31, and those for two-shade differences were between 0.65 and 9.78. Conclusions: Significant deviations in ranking exist between the chromameter measurement and value-based Bioform shade ranking. The Lab ranking by chromameter measurements does not correspond Bioform shade ranking.

Back to the Prosthodontics Research Program
Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

Top Level Search