Abstract: Objective： To investigate which shade guide, Vitapan Classical or Vita Bleachedguide 3D-Master, is better matched with the color of teeth in judging whitening effect, by comparing the color difference between shade tabs and corresponding teeth underwent cold light tooth whitening. Methods: A total of 60 patients underwent Beyond cold light tooth whitening from May 2014 to April 2016. The patients were divided into two experimental groups according to the shade guide used. Vitapan Classical shade guide was used to judge whitening effect in one group, and Vita Bleachedguide 3D-Master shade guide was used in another. Shade matching was carried out before and after whitening in both the two groups, and the results were recorded by digital photographs. Shade matching procedures were carried out by two doctors independently. If they chose the same tab, it would be seen as the shade matching result; While if they chose different tabs, another doctor would be invited to make a decision. Photographs were taken in preset conditions: intraoral photos of the full dentition in the front, and the proportion of shooting was 1 ∶3; aperture was F22; shutter speed was 1/200; intensity of flash was M/8; ISO value was 200. The photographs were analyzed by Photoshop software. Chromatic values were measured, and color diffe-rence values were calculated. Measuring of chromatic values was carried out by three doctors indepen-dently, and all the photos were measured twice by each doctor. Six measure results of each photo were recorded, and the maximum and the minimum were excluded, then the mean was seen as the final result. The color difference values were compared by independent-sample t test. Besides, changes of shade tabs after whitening in the two groups were recorded. Results: Color difference value was 5.06±1.71 in Vitapan Classical group, and 3.39±1.36 in Vita Bleachedguide 3D-Master group. There was statistically significant difference between the two groups (t=4.68，P<0.001). Change of shade tabs was 3.63±1.75 in Vitapan Classical group, and 2.23±1.01 in Vita Bleachedguide 3D-Master group. Conclusion: Vita Bleachedguide 3D-Master is better matched with the color of teeth, so it is preferred in judging the effect of cold light tooth whitening.

Key words: STooth bleaching, Shade guide, Color difference