Variations in L*a*b* Values of Vitapan 3D Master Shade Guide

Purpose: To measure the variations in L*a*b* values of a group of 25 Vitapan 3D-Master shade guides and to assess whether shade guides are indeed interchangeable.

Methods: The L*a*b* values of individual shade tabs were measured with a LabScan XE scanning spectrocolorimeter(Hunter Associates Laboratory) with a special attachment for reproducibly positioning shade tabs. Each shade guide (Vitapan 3D-Master Shade Guide, Vident) contained 29 shade tabs. One shade guide was arbitrarily selected to determine the reproducibility of the experimental method. Reproducibility was determined by measuring and them removing each shade tab 10 times. Twenty-five additional shade guides were used for the comparison test. The tabs of each of the 25 shade guides were measured five times in the SSC. All measurements were performed with the Universal software V4.10. (Hunter Associates Laboratory). The standard deviation of E (Esd) and the range of E (Er) for each of the shades were used as a D E value to assess color differences.

Results: For the reproducibility measurements, the shades had values for Er varying from 0.03 to 0.40 and Esd was between 0.01 and 0.12. This established the detection limit for our method for each of the shades. For the group of 25 shade guides, Er varied from 0.51 to 2.61 and Esd from 0.15 to 0.85. The difference between the means of Er for the 25 guides is significant at p<0.05. The largest reproducible Er observed was 2.61 for shade 3M1.

Conclusions: The differences observed between shade guides are larger than the variations induced by the experimental method. The difference in E values between shades 3M1 and 3M2 is 1.43; hence an Er of 2.61 between the shade tabs of the same shade is clinically significant.

This research was funded by the University of Tennessee Alumni Research Grant.