bleaching effect of ozone on pigmented teeth

background: there have been numerous researches on ozone application in dentistry; yet the data regarding its whitening effect is very limited. the present study compares the bleaching effect of ozone with offi ce bleaching. materials and methods: in this experimental study, 15 maxillary premolar teeth were selected and sectioned mesio-distally and bucco-lingually. the sections were then placed in tea for 1 week according to the sulieman method and were divided into three groups each comprised of 15 sections. the samples were bleached as followed; group i: bleached with 35% hydrogen peroxide in three intervals of 8 min each, group ii: underwent ozone treatment using ozotop unite for 4 min and group iii: bleached with a combination of both methods. the color indices of the samples, i.e., (a) green-red pigment, (b) blue-yellow pigment, (l) brightness, (δe) overall color change, were evaluated pre- and post-bleaching utilizing a digital camera, photoshop software and cie lab index. the color changes of specimens then were calculated and analyzed through randomized analysis of variance and tukey tests. p < 0.001 was considered to be signifi cant. results: the color change (δe) in group ii was signifi cantly lower than those in the two other groups ( p < 0.001). there was no signifi cant difference between the color change of groups i and iii ( p = 0.639). in addition, the results of l, a and b brought forth a similar pattern to the fi ndings obtained from δe. conclusion: the hydrogen peroxide gel has a more powerful whitening effect than ozone; in addition, ozone has no synergistic effect when is used simultaneously with hydrogen peroxide. key words: hydrogen peroxide, ozone, tooth bleaching