Use of a chroma meter to compare the shade change for two professional tooth whitening systems

Objective: Although common, use of shade guides to measure bleaching effectiveness carries risk for bias, particularly in comparative trials involving dissimilar products. This randomized clinical trial evaluated an objective method for shade measurement to compare shade changes for two professional vital bleaching systems. Methods: Twenty healthy adults were randomized to either a whitening strip containing 6.5% hydrogen peroxide or a custom tray-based, hydrogen + carbamide peroxide bleaching system. Shade change was measured objectively over a 14-day period using a portable chroma meter (Shofu® ShadeEye-Ex). Shade measurements were collected in triplicate from the facial cervical one-third of the maxillary right central and lateral incisors. Effectiveness was determined by comparing ranked (1-16) shade scores using standard methods. Results: In the 6.5% whitening strip group, individual improvement averaged 4.0 shades compared to 1.4 shades for the hydrogen + carbamide peroxide tray group. Both the strip group (p < 0.0001) and tray group (p=0.013) differed significantly from baseline with respect to objectively measured tooth shade. Between-group comparisons showed that the 6.5% whitening strip averaged an additional 2.7 shades improvement over the hydrogen + carbamide peroxide tray system, with these groups differing statistically (p=0.0011). Conclusion: When shade change is measured objectively using a chroma meter, the 6.5% hydrogen peroxide strip system yielded a nearly three-fold shade change compared to the hydrogen peroxide + carbamide peroxide, custom tray-based system. Such methods may help limit examiner bias in bleaching clinical trials.