The safety-in-use of 10% carbamide peroxide (Opalescence) for bleaching teeth under the supervision of a dentist.

Fears that the dentist-supervised use of a product that contains carbamide peroxide and that emits hydrogen peroxide may not be safe from the viewpoints of toxicity and cancer risk were engendered by unrealistic animal tests. These fears prompted the UK Government Departments of Trade and Industry (DTI) and of Health (DOH) to try to prohibit the marketing of Opalescence (manufactured by Ultradent Inc.). Faced with the fact that Opalescence had already been awarded a CE mark under the EC Medical Devices Directive, the DTI and DOH attempted to bring about its prohibition by reclassifying Opalescence as falling under the EC Cosmetics Directive, according to which the marketing of products containing more than 0.1% hydrogen peroxide is not permitted.