Teeth Whitening can be a highly effective yet very simple method of lightening the colour of teeth, which does not need the removal of any tooth structure. It cannot make a colour change, but enhances the existing shade.

The whitening product is applied to the teeth by the dentist, using a specially made tray, which fits into the mouth like a gum shield. The chemical may be activated using heat or heat and light combined. The active ingredient in the product is normally hydrogen peroxide or carbamide peroxide. If the teeth have not been root treated, the canal, which previously contained the nerve, may be reopened and the product is inserted. In both cases, the procedure needs to be repeated until a satisfactory shade is attained.

Initially, you will need two or three visits to your dentist. Your dentist will need to make a mouthguard and will need to take impressions for this at the first appointment. Once your dentist has started the treatment, you will be required to continue the treatment at home. This will require regular applications of the bleach over a period of 2 - 4 weeks for 30 minutes to 1 hour at a time. However some products have now been developed, which can be applied for up to eight hours at a time, which means that a satisfactory result can be obtained in as little as one week.

Everyone is different; and just as our hair and skin colour varies, so do our teeth. Some teeth have a yellowish tinge, some are more beige - very few are actually 'white'. Teeth also yellow with age and can become stained on the surface through daily exposure to foods and drinks such as tea, coffee and blackcurrant. Calculus or tartar can also affect the colouration of the teeth. Some people may have internal staining which can be caused by certain antibiotics or minute cracks in the teeth, which take up stain.

Treatment results may vary depending on the original shade of the teeth. Teeth will tend to darken slightly over time. The effect lasts for around one to three years, although sometimes it can last longer. Some people find that their teeth are sensitive for the first few days after treatment, but this wears off after just a short while.

Over-the-counter kits are not recommended as they contain only a small concentration of hydrogen peroxide, which reduces the effectiveness of the product. Some also contain mild acids, whilst others are abrasive. Although these products are cheaper, whitening is a complicated treatment procedure and should only be carried out by a dentist after a thorough examination and assessment of your teeth. It is very important to follow the instructions issued by your dentist and to ensure that you attend any follow-up appointments recommended.

Whitening can only enhance your existing shade. Whitening also only works on natural teeth. It will not work on any type of 'false' teeth. This includes dentures, crowns and veneers. If dentures are stained or discoloured, it may be worthwhile visiting the dentist and asking him or her to clean them. Stained veneers, crowns and dentures may need replacing; again ask your dentist.

There are several whitening toothpastes now available on the market. Although they do not affect the natural colour of the teeth, they are effective at removing staining and therefore improving the overall appearance of the teeth. Whitening toothpastes may also help to maintain the appearance, once teeth have been professionally whitened.