DENTISTS yesterday warned patients desperate for the perfect smile about the dangers of beauty salons and spas offering potentially damaging teeth-whitening treatments.
The British Academy of Cosmetic Dentistry (BACD) said it had been alerted to chemicals being used to whiten teeth usually recommended only for industrial purposes.
They said the chemicals could erode the enamel, making teeth look darker.
The BACD said such treatments should always be carried out by dentists rather than beauty therapists.
The growth of teeth-whitening has been boosted by celebrities such as Tom Cruise and Kate Beckinsale, whose pearly-white grins have encouraged the public to follow suit.
But high prices, sometimes more than 1,000, mean many people have looked for cheaper options such as those offered by beauty salons.
The BACD issued its warning after being alerted to the case of a 23-year-old women whose teeth had darkened after treatment at a beauty salon. The academy found that the chemical used on Stephanie Ramezan's teeth was not regularly used for whitening and could dissolve the enamel.
Ms Ramezan, who works in the City, opted to have her teeth whitened at a local spa.
Although she was surprised to find out that a dentist did not perform the treatment, she decided to go ahead.
"I had been led to believe that teeth-whitening can be expensive, over 300, but this was less than 200.
"I asked the therapist and she said it was a special New Year offer," Ms Ramezan said.
"I had checked out their website beforehand and it all seemed reputable, so I went ahead and booked the session."
But two days after having the treatment, Ms Ramezan noticed that her teeth seemed darker.
She returned to the salon to ask what had happened, but the beauticians were unable to help. Repeated attempts to contact the doctor who ran the spa failed.
Eventually she went to see BACD dentist Oliver Harman, who noticed that the surface of the tooth had been damaged.
He investigated and found that the salon - part of the Smile Spa chain - was using a substance called chlorine dioxide.
The BACD said it was not generally used for whitening and the acid involved was usually recommended only for industrial cleaning or water purification.
Mr Harman said: "What immediately worried me is that they seem to be using strong chemicals which include orthophosphoric acid, which is what dentists use to dissolve enamel when bonding fillings.
"In addition, they hadn't even bothered to scrape the plaque off Stephanie's teeth before bleaching, which is common practice so there can be an even finish."
Dr Christopher Orr, presidents of the BADC, said: "We are seeing many cases of people who, driven by either convenience or cheap pricing, choose to have their teeth whitened at local beauty salons or 'spas'.
"Not only are the treatments performed by non-dentists, but some of these chemicals aren't accepted material for this cosmetic use and could cause considerable damage."
Dr Nigel Carter, chief executive of the British Dental Health Foundation, said: "We recommend that people considering whitening treatment go to their dentist for best results.
"Your dentist will check for any problems in the mouth before carrying out treatment."
But Mark Eckley, managing director of Smile Spa, which has branches across the UK, said many salons used chlorine dioxide and it was completely safe.
"We have carried out more than half a million of these treatments and have never had an insurance claim made against us," he said.
Mr Eckley said beauticians did administer the treatment, but they were fully trained to do so.
"Dentists are just trying to protect their own businesses by making these claims as they see how successful we are," he said.
• THE ravages of coffee, smoking and red wine mean a growing number of people are opting to have their teeth artificially whitened.
Q: What does tooth-whitening involve?
A: Most dentists use peroxide-based products, but salons have started offering alternatives. A gel is applied to the teeth. As the active ingredient breaks down, oxygen gets into the enamel and the colour lightens.
Q: How long does treatment take?
A: It can usually be done within three to four weeks, with two or three visits to the dentist. Whitening will also have to be applied regularly at home.
Q: How long does it last?
A: The whitening effect can last for up to three years, depending on the individual.
Q: What are the side-effects?
A: Some people may find that their teeth become sensitive to cold. Discomfort in the gums and white patches on the gum line may also occur but are usually short-lived.