Sunday, March 9, 2008

What is hydrogen peroxide and what is it used for?

Hydrogen peroxide is used as bleaching agent in tooth whiteners and in some toothpastes and is a highly reactive chemical containing hydrogen and oxygen. It is used mainly in the production of other chemicals and to bleach paper and textiles. Moreover, contact lenses can be disinfected with highly diluted hydrogen peroxide.

What health effects of hydrogen peroxide have been observed?

Swallowing a large dose of hydrogen peroxide can be lethal.

Highly diluted hydrogen peroxide solutions are non-irritant or mildly irritant. However, animal tests have shown that, when exceeding certain concentrations, hydrogen peroxide can cause irritation of eyes, skin, and the inside of mouth, stomach, and intestine. The use of eye drops and contact lens solutions containing some hydrogen peroxide can irritate the eyes.

Mouth rinses that contain small amounts of hydrogen peroxide and are used once or twice per day do not seem to harm the inside of the mouth, even in the long term. On the contrary, they can improve gum health.

Hydrogen peroxide can act as a weak cancer promoter, meaning it can slightly stimulate the growth or multiplication of cancer cells. There is not enough data to evaluate potential effects of hydrogen peroxide on reproduction and development.

People with certain genetic disorders are more vulnerable to hydrogen peroxide because their bodies cannot break it down effectively.

How is hydrogen peroxide used to whiten teeth?

Tooth whitening products can be applied at home in three different ways:
  • using strips that are stuck onto teeth
  • custom made mouthguards that maintain the whitening product on the teeth
  • gels that are painted directly on the teeth

Tooth whiteners use hydrogen peroxide or carbamide peroxide as the whitening agent. Peroxide acts by passing into the tooth and reacting with the molecules that cause stains or discoloration. In general, the more peroxide, the greater the whitening power. Depending on their peroxide content, tooth whitening kits are either freely sold over the counter for home use, dispensed by dentists for home use, or exclusively applied by dentists in their offices. In the European Union, oral hygiene products may only be sold freely to consumers if they contain no more than 0.1% hydrogen peroxide whereas in the USA, whitening products are sold at higher concentrations.
The length of treatment depends on the level of discoloration and the whitening product used. It ranges from short interventions in the dental office to applications at home lasting minutes/hours per day and repeated over a number of days.
Some toothpastes also contain small amounts of
hydrogen peroxide.

How much hydrogen peroxide is an individual exposed to during tooth whitening treatment?

Concentration of hydrogen peroxide on the gums falls rapidly during treatment.

How much hydrogen peroxide is released into the saliva during tooth whitening treatments depends mostly on the amount of hydrogen peroxide in the product being used and the product type and only partly on the amount of saliva produced.
During a tooth whitening treatment procedure, the concentration of hydrogen peroxide on the gums and in the saliva falls rapidly because hydrogen peroxide is broken down quickly.
It is estimated that up to 25% of the hydrogen peroxide applied by tooth whitening products is swallowed.

What should be considered before a tooth whitening treatment?
Before engaging in tooth whitening treatment, a dentist should be consulted.

Above 0.1% hydrogen peroxide, tooth bleaching is not just a simple cosmetic procedure. It is important that the dentists diagnose the cause of the staining, predict whether the stains can be removed or not, check whether patients have any other oral health problems, and counsel patients about the best way of dealing with this esthetical problem. As already mentioned above, common undesirable side effects of tooth whitening treatment are increased tooth sensitivity and mouth irritation. Such effects usually disappear within a few days. The surface of fillings and other restorations can be affected. Hydrogen peroxide can act as a weak cancer promoter, meaning it can slightly stimulate the growth or multiplication of cancer cells. Tobacco use, alcohol abuse, and specific genetic predispositions increase the risk of oral cancer. Hydrogen peroxide may therefore further increase this risk, especially when the treatment is repeated. This may be of concern as smokers are likely candidates for tooth whitening. The risk of harmful effects may be greater for people who have pre-existing oral diseases.