Dental Treatment

This factsheet is for people who are planning to have their teeth whitened, or who would like information about it.

Tooth whitening is a way of lightening the natural colour of teeth using bleaching methods. Tooth colour varies among people. Teeth can become discoloured through red wine, coffee, smoking and age.

Your care will be adapted to meet your individual needs and may differ from what is described here. So it’s important to follow your dentist’s advice.

About tooth whitening


As you get older, your teeth can become darker naturally. This process is often increased by drinking tea, coffee, red wine or other food and drink with strong colourings. Another major cause is smoking, which can make your teeth appear yellowed. Tooth decay, fillings and tartar build-up can also contribute to discolouration.


If the nerves and blood vessels in teeth are damaged through decay or a knock, the tooth may become darker.

Some types of staining can be caused by diseases or medicines. For example, if a type of antibiotic called tetracycline is given to children whose teeth are still developing, their adult teeth may form with a yellow or green tinge.


What are the alternatives to tooth whitening? 

Simple ways to improve the appearance of discoloured teeth include:

  • regularly having your teeth scaled and polished to remove any tartar that has built up

  • following advice about preventing tooth decay

  • brushing regularly

  • stopping smoking

  • cutting down on strong-coloured food and drink to stop stains returning

Whitening toothpastes are slightly abrasive, which may help to remove surface staining, but they don’t alter the natural shade of your teeth. Experts are currently reviewing how effective whitening toothpastes are.

Your dentist can give you advice about replacing your metal fillings and crowns with tooth-coloured ones.

Getting advice about tooth whitening 

Your dentist can give you advice about the different bleaching methods and what will be the most effective for you. For example, the colour that your teeth are now will affect how well bleaching works. You also need to consider your skin complexion so that the treatment looks as natural as possible.

Home kits may not be suitable if you have damaged nerves causing discolouration. You may need stronger products that can only be used by a professional.


It’s important to remember that if you have tooth-coloured fillings or bonding material, these won’t bleach, and if you bleach your teeth, they will be a different colour. In this case, veneers may work better.

About tooth whitening products


Professional tooth bleaching

In the past, tooth whitening could only be done by dentists. However, now, provided a dentist has recommended that you can have the procedure, dental hygienists and dental therapists are also able to carry out tooth whitening.

Some tooth whitening techniques are described here.


External bleaching

This is when the bleaching gel is placed on the outer (external) surfaces of the teeth. Procedures that use this technique are described here.

  • Home’ bleaching – Firstly, your dentist makes the rubber mouth trays so that they fit your teeth precisely, and secondly, the bleaching gel may be stronger and therefore more effective. Your dentist will give you tubes of bleaching gel and instructions on how to put the gel in the mouth trays. You will need to wear the mouth trays for 30 minutes to one hour each day, for two to four weeks. It may take three to four weeks to achieve the colour that you want. Your dentist will give you detailed instructions. There is some evidence that  home bleaching kits work, but some products may be better than others. Possible side-effects of home bleaching include tooth sensitivity and gum irritation. Also, the long-term effects of using these techniques aren’t known. Home bleaching is only recommended when done in consultation with your dentist.


  • In the dental surgery – ‘power’ or ‘laser’ bleaching. Your dentist may put a rubber seal around your teeth to protect your gums depending on the concentration of bleaching agent used. The bleaching gel is then placed onto your teeth and a special, bright light is used. This is an attempt to enhance the whitening process. The appointment may take one to two hours.


  • Combined bleaching, sometimes also known as ‘power’ bleaching – both the home bleaching and surgery are used in combination. The home bleaching stage may occur before or after surgery – this depends on the type of treatment used. Your dentist will give you instructions.