The aim of the study was an assessment of the reproducibility of colorimetric measurements of samples of the VITA Classic colour key with the use of two dental spectrophotometers.
Material and methods:
In order to determine the reproducibility of colorimetric measurements, 16 porcelain samples from the VITA Classic colour key were assessed. Each sample was assessed using the parameters: L*, a* and b*, describing the colour as a point in a three-dimensional system of co-ordinates. 10 measurements were taken using a Spectroshade spectrophotometer (MHT), and 10 using an Easyshade spectrophotometer (VITA GmBH). For each series of measurements taken by one appliance, comprising of 10 elements, a mean value of the parameters was determined, i.e., L* (lightness), a* (red/green chroma) and b* (yellow chroma), as well as their standard deviations. These results were than analyzed using the Mann-Whitney test, with the help of Statistica ver. 6.0.
Results:
In the case of measurements taken using the Spectroshade spectrophotometer, the average standard deviation was 0.0457 (p=0.0000) for L*, 0.1087 for a*, and 0.1324 for b*. In the case of Easyshade the respective values were: 0.1732, 0.1371 and 0.1121.
Conclusions:
1. Both appliances used for the colorimetric evaluation of teeth and restorations have a similar reproducibility of a* and b* measurements.
2. Under the conditions of this study, the Spectroshade spectrophotometer showed significantly greater reproducibility of measurements of lightness (L*) of samples of a colour key.