Wang S, et al. - Experts probed the alternative bleaching regimes such as sodium perborate (S) and thiourea-hydrogen peroxide (T) for tooth discolouration due to bacterial contamination in traumatized teeth. Compared with blood/bacteria-stained teeth, blood-stained teeth were significantly darker and red. Using either S or T, blood-stained teeth retained significant redness compared with blood/bacteria-stained teeth after bleaching. Findings suggested more effectiveness of T bleaching regime than S.