Objective: Documenting change in color during treatment with tooth whitening agents is problematic. Electronic measurement devices have been used, but are typically bulky and expensive. This project compares color measurements made with two devices. #1 is a new, relatively inexpensive intra-oral spectrophotometer (group CID; Chromident; JJL Technologies) which is small and convenient to use. #2 is a tristimulus colorimeter (group CM; Chroma Meter CR-321; Minolta). Methods: Four measurements of each shade tab in a Vita Classic Shade Guide were taken, and the CIE L*a*b* coordinates recorded. All measurements were taken over a three-hour period. The color difference between shade tabs was calculated. Color difference is expressed as Delta E (D E). It was calculated using the formula:

D E=[(L*₁ – L*₂)² + (a*₁ – a*₂)² + (b*₁ – b*₂)²]^1/2

Errors associated with the short-term repeatability of these measurements was assessed by calculating the Delta E color difference (D E _CD) using this formula:

D E _CD=|D E _avg – D E*_ind|

D E _avg is the color difference between two tabs using an average of the values from the first three trials, and D E*_ind is the color difference between two tabs using data from the fourth trial. Delta Es were calculated for all 120 combinations of tabs. Results: The mean D E _CD for group CID was 0.29 and for CM, 0.37. Smaller D E _CD values represent better repeatability. There was a significant difference between the two groups (Mann-Whitney Rank Sum; p < 0.025). Conclusion: With these specimens the new intra-oral spectrophotometer proved to be more reliable than the tristimulus colorimeter. (JJL Technologies supported this project by providing one of their units).

Back to the Dental Materials: VIII - Others-Non-metallic Program
Back to the IADR/AADR/CADR 80th General Session (March 6-9, 2002)

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