I have been asked this question by people from time to time. I guess because tooth whiteners contain hydrogen peroxide. The answer to this is no, they do not. Evidence for this comes from a review of many other published studies which appeared in the Journal of Esthetic and Restorative Dentistry (volume 3, issue 3) in June 2006. The compiled results concluded that tooth whitening products containing hydrogen peroxide do not cause or increase the risk of oral cancer when used as directed. Exposure to hydrogen peroxide in whiteners is too low and to short in duration (30-60 minutes) to create any changes in oral tissues to increase any oral cancer risk. In fact, the evidence from this review which included over 4000 human subjects showed no evidence of oral cancer or other effects associated with risk of oral cancer.
Normally when used as directed the concentration of hydrogen peroxide in these products decreases to nearly undetectable levels within 15 minutes to one hour. Over the counter whitening products have significantly lower peroxide concentrations than those applied in a dental office under close supervision and isolation.