Dark truth about teeth whitening

With more than 100,000 people in Britain trying tooth-whitening treatments last year, it seems we have finally succumbed to the American belief that the brighter and whiter your smile, the younger and happier you'll feel.

But is the quest for a bright, sparkling smile as safe and effective as dental brochures claim? Cosmetic dentists are increasingly coming under fire for making exaggerated claims for costly laser-bleaching treatments. Whitening toothpastes have been criticised for containing abrasive particles which can wear tooth enamel away, and some researchers say that hydrogen peroxide, the most commonly used bleachingagent, may be carcinogenic and weaken teeth.

There are three main "whitening" approaches. Toothpastes containing anti-staining agents or hydrogen peroxide cost a pound or two more than regular toothpastes and are used daily by hundreds of thousands of people.

Home-use bleaching kits, costing around £100, involve placing a hydrogen peroxide solution in bleaching trays which are worn over patients' teeth at night for up to two weeks. These claim to lighten tooth colour by up to six or eight shades and are the second most popular treatment.

The latest, most expensive method is laser tooth whitening, in which a hydrogen peroxide solution painted onto a patient's teeth is subjected to a strong light that speeds up the lightening process. This procedure, taking between 15 minutes and one hour, claims to lighten teeth by up to 11 shades but can set you back more than £600.

These techniques all target stain particles from food and drink which get trapped in the surface layers of tooth enamel. Toothpastes try to remove them, while hydrogen peroxide bleaches them.

But what is the evidence to show that these treatments work? While whitening toothpastes may slow the staining process, a recent study in the British Dental Journal found that the vast majority failed to live up to claims that they make teeth lighter.

"Whitening toothpastes remove stain particles and are far less abrasive than they once were, but claims that they lighten teeth are doubtful," says Mervyn Druian of the London Tooth-Whitening Centre. "Some contain hydrogen peroxide, but it is so weak and unstable by the time you use it, the effect is often minimal."

Bleaching procedures, however, can be very effective and fears over their safety have been largely dispelled.

"Bleaching kits and laser whitening can lighten teeth considerably," says Druian. "Each technique can make teeth up to 11 shades lighter. The main difference is that home bleaching takes up to two weeks, whereas a laser treatment takes around 30 minutes."

There is little evidence to support the concern that hydrogen peroxide demineralises teeth, making them weaker. Some researchers have claimed the chemical is a potential carcinogen. However, if applied properly, it should only come into contact with tooth enamel, which is dead anyway.

"The main risk with hydrogen peroxide, whether used in a tray at home or at the dentist, is that it irritates and bleaches the gums," says Druian. "For this reason, dentists apply bleaching solutions to the teeth very carefully."

Bleaching techniques, however, won't work for everyone. Tooth staining is also caused by antibiotics such as tetracycline, which discolours the tooth enamel itself.

Cosmetic dental practices claim - often unrealistically - that laser whitening can remove this type of staining too. In fact, there is only a 10 or 20 per cent chance of bleaching techniques working in these cases.

These limited chances of success were not explained to her, claims Jacqueline Stokes, a sales consultant who spent £600 on a laserwhitening treatment which she says had virtually no effect.

"I went to a clinic in south-west London a few months ago, having-seen one of its pamphlets. Inside it were 'before' and 'after' pictures of teeth with tetracycline staining, like myself," says Jacqueline. "They were amazing - the 'before' pictures showed teeth with yellowish brown staining and in the 'after' pictures they were ivory-coloured.

THE treatment was very expensive at £600, but cheaper than veneers. I'd hated my teeth from a young age. I've always felt self-conscious smiling. "The dentist said I'd see a definite difference and did two 15-minute laser treatments on my teeth," Jacqueline says. "But when I looked in the mirror, I could still see the stains. I hoped that my teeth would lighten on my way home - but they were as stained as before, and my friends agreed.

"I'm furious. The chances of it not working weren't explained at all. The clinic actually promoted how well tetracycline stains could be removed with this technique. I feel I should be given a refund."

John O'Maoleoin, of the British Dental Association, agrees that the chances of a treatment working should always be explained clearly. "While most tooth-whitening procedures are safe and effective, patients need to speak to their dentist about what sort of effect they can have, so that they have realistic expectations. It wouldn't be fair for patients' hopes to be raised unduly."

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