TEETH-WHITENING products sold over the counter are often either ineffective or could damage teeth, warns the British Dental Association.
It cites a study published in the British Dental Journal warning that sodium chlorite, the active ingredient found in three over-the-counter (OTC) products, could in the presence of acid "significantly reduce the hardness of the teeth and increase the likeliness for future surface abrasions of the teeth".
The BDA also states that it is aware of DIY teeth-whitening kits seized by trading standards that contained dangerous levels of hydrogen peroxide - more than 33 per cent. High-level bleaching gels can cause mouth infections, blistering and burns to gums, damage to nerves and tooth enamel and gum-shrinking.
There are also doubts over the effectiveness of legal OTC teeth whitening products which contain no more 0.1 per cent hydrogen peroxide and may be too weak to make any difference to the colour of teeth.
The BDA's scientific adviser, Professor Damien Walmsley, said: "At best, people may be wasting their money buying over the counter and online products to whiten teeth. Home whitening kits are likely to take longer and be less effective than treatment from the dentist. While hydrogen peroxide, as used in dental practices, is the gold standard for whitening teeth, the lack of clarity over chemicals used in over the counter and online products means you could be gambling with your teeth.
"Some online products have been found to contain dangerous chemicals, including toxic or banned substances that can severely burn gums, or irreparably damage teeth.
"Dentists are trained to consider a patient’s wider health and detect problems, such as gum disease, that impact on the suitability of an individual to have their teeth whitened. They also know what whitening products are effective to use, and safe for teeth and gums."