Comparative clinical efficacy of two professional bleaching systems.

A randomized, parallel, examiner-blind clinical trial was conducted to compare two professionally dispensed vital bleaching systems. A total of 20 subjects were randomized to either the Crest Professional Whitestrips system or the Nite White Excel 2 tray system, balancing for baseline tooth color. During the 2-week treatment period, subjects were instructed to use the strip system for one-half hour twice daily (14 contact hours) and the tray system for 2 hours daily (28 contact hours). Only the maxillary teeth were treated, and all bleaching was unsupervised. Whitening was measured objectively by comparing digital images of the maxillary anterior dentition at pretreatment and posttreatment. Compared with baseline, both the strip and tray systems exhibited statistically significant decreases (P < 0.05) in yellowness (delta b*) and increases in brightness (delta L*). Compared with the tray-system group, the strip-system group experienced significant additional whitening (P < 0.03), as evidenced by a 62% to 209% improvement in tooth color (delta b*, delta L*, and delta E*) after 14 days. Both systems were generally well tolerated, and none of the subjects discontinued treatment early because of an adverse event. Under the conditions tested, this clinical trial demonstrates that the 14-contact-hour treatment with the strip system resulted in superior whitening efficacy compared with the 28-contact-hour treatment with the tray system.