The primary mode of action of many teeth whitening toothpastes is abrasion. The formulation of the typical whitening toothpaste will be such that it includes minute, mildly abrasive particles (usually aluminum oxide, dicalcium phosphate dihydrate, hydrated silicas or calcium carbonate). The scrubbing motion of the bristles of a toothbrush in combination with the presence of these small particles creates an abrasive action that can have an effect where it scours debris off the surface of teeth. Some toothpastes designed for smokers are more abrasive than ordinary family toothpastes.
The formulations of some teethwhitening toothpastes include peroxide compounds, but at very low levels.
Home toothwhitening kits
Home toothwhitening kits include a strip or mouth-guard which is filled with a hydrogen peroxide gel, and applied to the teeth. This is usually worn for several hours a day, for up to 15 days. The oxidising agent in the gel penetrates the porous crystalline enamel structure of the tooth and oxidises the stain deposits, thus whitening the tooth.
The concentration of hydrogen peroxide in such kits must not exceed 0.1% under current UK and EU legislation, and so it would be a relatively slow process.
Are toothwhiteners safe?
The UK and EU's policy on the availability of home teethwhitening products is much more stringent than in other parts of the world, where it is possible to purchase products with a higher concentration of hydrogen peroxide.
The law (the UK Cosmetics Regulation) does not allow the level of hydrogen peroxide in tooth whitening products for home use to exceed 0.1%.
Other bleaching agents are used in some home use toothwhitening kits.
In all cases it is important to follow the manufacturers' instructions for use carefully to avoid irritation of the mucous membranes of the lips, cheeks and gums. Even with careful use, a small minority of people do notice a temporary tooth sensitivity to hot and cold after toothwhitening.
Tooth whitening products containing levels of hydrogen peroxide between 0.1% and 6% may only be sold to dental practitioners. For each cycle of use, the first use can only be carried out by dental practitioners or under their direct supervision if an equivalent level of safety is ensured. Following the first cycle of use, the product can be provided to the consumer to complete the cycle of use. These products can only be used on consumers above the age of 18.
Whilst the restrictions on hydrogen peroxide-based toothwhitening products sold to consumers in the UK and Europe are very stringent, other means of toothwhitening are being explored, most recently the concept of bleaching teeth using light technology.
Where can I find out more?
The National Hair and Beauty Federation (NHBF) has a factsheet providing helpful information and advice, while reminding hairdressers and beauty therapists that it is illegal for tooth whitening to be carried out within hair or beauty salons.