The British Dental Association (BDA) and British Academy of Cosmetic Dentistry (BACD) said there was no evidence that chlorine dioxide was effective, but the chemicals could wreck the surface of teeth.

Chlorine dioxide is an oxidising and bleaching agent mostly used as a pesticide, as an additive in processed food and to purify water supplies.

Stuart Johnston, a BDA spokesman and chairman of the Council of European Dentists’ working group on tooth whitening, said that he had searched in vain for good evidence that the chemical could be of use in cosmetic dentistry. “The chemicals involved are well known in industry but we do not currently support their use in dentistry,” he said.