Repeatability of a specially designed intraoral colorimeter

A specially modified Minolta CS-100 colorimeter with a DP-101 data processor was designed for intraoral use. To test the repeatability of the results obtained with this specially modified unit, five porcelain and five acrylic resin denture teeth were mounted in a fixed position in front of a fixed mounted meter. Three L*a*b* readings were taken per tooth and mean values were obtained after calibration as a baseline measurement. The readings were repeated on day 3 without recalibration and on day 8 after recalibration. The same-day repeatability showed delta E values < 0.4 in nine of the 10 samples. The day 3 repeatability showed delta E values < 0.4 in only 2 of the 10 samples. The day 8 results, after recalibration, showed delta E values > 0.4 in all of the samples, with a range of 0.57 to 2.75. In vivo testing was performed on five patients with delta E values that ranged from 1.1 to 32.1.