What is Teeth Whitening?

Teeth whitening is a cosmetic procedure that is used to make the surface of the teeth appear whiter. Although teeth whitening cannot turn the teeth brilliant white, it can be a very effective way of lightening the existing color, without causing any damage to the tooth’s surface.

The effects of teeth whitening are not permanent and can last anywhere from a few months to three years. The amount of time the effects last for varies between individuals, but, in general, the effects do not last as long if a person stains their teeth through smoking or drinking tea, coffee or red wine, for example.

In Europe and some other countries, only a qualified dental professional is allowed to carry out teeth whitening and when it is performed in beauty salons by people with no dental qualifications, the procedure not only poses a risk to oral health, but is also illegal.

Professional teeth whitening

The most common method of whitening the teeth is professional bleaching. This involves several visits to the dentist over a couple of months. The dentist takes an impression of the teeth which is used to create trays that fit onto the teeth like mouth guards. The trays are filled with a bleaching gel and the patient is shown how to carry out the procedure at home.

The gel is applied for a certain amount of time, which varies depending on how severe the discoloration is and how white a person wants their teeth to look. However, generally, the gel is applied for between 30 and 60 minutes each day, for between two and four weeks. Some products can be applied for up to eight hours at a time, in which case the process may be complete in as little as a week.

Home kits

It is possible to buy home kits to bleach the teeth, but these are associated with risks. Although the kits are cheaper, they are not always subjected to safety checks and the gel used may be more acidic. Furthermore, if the mouth guard has not been created by a qualified professional, it may be a poor fit, meaning the bleaching gel could leak into the mouth and damage the teeth and gums.

In Europe, it is illegal to sell any kits containing more than 0.1% hydrogen peroxide, which means the gel is not strong enough to offer effective whitening. Home whitening may be more common in other countries where stronger gels are sold, but people should be wary of buying these kits over the internet because they may contain gels that are acidic and abrasive.

Laser whitening

This is another form of teeth whitening that is carried out by a qualified professional. It involves painting a bleaching product onto the teeth, which is then activated by a laser to accelerate the whitening reaction. This procedure only takes around one hour and is also referred to as “power whitening” or “chair-side whitening.”

Whitening toothpaste

Several whitening toothpastes are available on the market. These products do not change the color of a person’s teeth, but they can be effective at removing any stains or discoloration that have accumulated, therefore helping to restore some of the natural color and improve the overall appearance of the teeth. These toothpastes can also be used to prolong the effects of a professional teeth whitening procedure.


Before embarking on teeth whitening, a person needs to be free of any oral diseases such as tooth decay, gingivitis or periodontitis. In addition, teeth should not be sensitive, cracked or injured.

Unless these conditions are diagnosed and treated adequately prior to teeth whitening, they may become further aggravated and interfere with the success of the procedure.

The steps involved in teeth whitening include:

  • A complete dental health check – A dentist and a dental hygienist can help diagnose and treat any problems with the teeth, gums and mouth before the teeth whitening procedure is carried out.
  • They can also advise whether teeth discoloration has a natural cause or is the result of injury or staining from food, antibiotics, tobacco or coffee. Once the cause is established, the procedure can be carried out with more realistic expectations.
  • Dentists may also advise on additional options such as the use of tooth-colored crowns, veneers, bonding materials or tooth-colored fillings.


The effects of teeth whitening can last for up to three years, although this is unlikely in people who smoke or drink tea, coffee or red wine, for example.

Some side effects of teeth whitening include sensitivity to the cold, gum discomfort, sore throat, and white patches on the gum line. These effects are usually short-term and clear up within a few days of the treatment. However, people should consult their dentist if any of these effects last longer than a few days.

After the procedure

People often find their teeth and gums feel much cleaner after a whitening procedure. People can increase the chances of their teeth staying white by cutting down on foods and drinks that stain the teeth and by stopping smoking.

Further Reading

Last Updated: Aug 23, 2018

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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