Dentists have expressed concern that some businesses that offer tooth whitening services in Ireland may be operating illegally.

New EU directives which regulate the use of the chemical used in tooth whitening products - hydrogen peroxide - came into effect late last year. They state that consumers can only be sold whitening products that contain no more than 0.1% hydrogen peroxide.

Products that contain more than that will have to be administered by a dentist in the first instance.

This means that anyone who wants to undergo tooth whitening must be examined by a dentist and have their first treatment carried out by that dentist. Any further treatments must be undertaken on the prescription of the dentist.

Meanwhile, products with more than 6% hydrogen peroxide are now illegal and those under the age of 18 can no longer have their teeth whitened in any instance.

However, according to an article in the Journal of the Irish Dental Association, four tooth whitening businesses when approached were unable to provide details on the gels they used for tooth whitening. Furthermore, just one of the four admitted that their clients had been seen by a dentist.

Dr Tom Feeney of the Irish Dental Association said that dentists are ‘very concerned' about this.

"The purpose of the new Cosmetics' Directive was to properly regulate the whole tooth whitening sector and to put an end to unregulated operators in the interests of patient safety.

"Many of the tooth whitening shops claim rapid success in the bleaching process, but are extremely reluctant to disclose the active ingredient in the gels they apply. This would raise suspicions that illegal concentrations of hydrogen peroxide are being used, as rapid one visit tooth bleaching is not possible with legal concentrations," Dr Feeney explained.

He said that the association was also concerned about the training and qualifications of those carrying out these procedures, as just one in four businesses said that a dentist had examined their clients.

"We believe this is wrong and that a dentist must always examine the patient to determine whether tooth whitening is a suitable treatment option and to ensure the absence of risk factors in the mouth. In addition tooth whitening is not appropriate for pregnant women or heavy drinkers or smokers," he commented.

Meanwhile, the association again appealed to people not to purchase tooth whitening products over the internet, as these can contain very high levels of hydrogen peroxide, ‘which could be lethal in the wrong hands'.

The association offers the following advice to people wanting to avail of tooth whitening:

-Only go to regulated professionals, i.e. dentists

-If in doubt ask for the Dental Council Registration Number

-Ask for the name of the product used and its concentration

-If a light is being used ask why - this has no effect

-If you have any concerns, contact the Irish Medicines Board at cosmetics@imb.ie