Why do teeth become discoloured?

A bright white smile is often seen as a desirable characteristic. However, teeth can become discoloured for a variety of reasons including:
Teeth naturally becoming darker with age
⦁ Smoking
⦁ Poor oral hygiene
⦁ Diet (drinking lots of red wine or coffee)
⦁ Trauma to a tooth
⦁ Genetic causes
⦁ Certain medication

There are many other factors that have not been listed. Before starting the treatment the cause of the staining should be identified by the dentist, as this will affect the treatment procedure and outcome.

What is tooth whitening?

Tooth whitening – also called tooth bleaching – is a way of lightening the shade of discoloured teeth. The active ingredient widely used for tooth whitening is hydrogen peroxide (carbamide peroxide). This is in the form of a gel/solution that is applied to the surfaces of the teeth to be bleached. Special trays are made for every individual patient to apply the whitening gel and the gums are protected at all times.

Whitening is a conservative approach to improving the appearance of stained teeth as no tooth structure is removed to make room for filling materials to be added. Tooth whitening should always be performed by a registered dental professional and must be prescribed by a dentist.

How does it work?

Carbamide peroxide lightens the overall appearance of the tooth by breaking down stains in the dentine (a layer that makes up the bulk of tooth structure). It is a powerful oxidizing agent that causes the darker molecules to become smaller and subsequently removed from the tooth.

Procedure

After your initial examination identifying the cause, the dentist will take the pre treatment shade of the teeth and often some clinical photos so there is a baseline to work from.
Impressions of the teeth are taken and a special tray is then constructed to fit the teeth. This tray will hold the whitening gel/solution and is individual to every patient.

In the dental surgery:
Hydrogen peroxide bleaching gel/solution is applied to the teeth and an accompanying light or laser may be used to speed up the treatment. The gums and other soft tissues are protected at all times to reduce the chance of irritation. This usually takes place under rubber dam to isolate the teeth and shield the gums.

At home:
A customized mouth guard is constructed that the whitening gel is placed into so it covers the teeth. Your dentist will then instruct you how to properly use the guard and the correct amount of time to leave it on for. Whitening can take up to a few weeks to work.

Are there any risks?

Whitening is generally a safe procedure but can cause some potential problems that are important to know about before starting the treatment:

The gums may become irritated due to the chemicals used. This is reversible and only usually occurs with higher concentration treatments that are performed by the dentist. In these cases the gums are always protected to reduce the likelihood of this occurring.

Bridges, crowns veneers and fillings, for example, will not get lighter by whitening. It is important to acknowledge this prior to commencing treatment, as existing restorations may need to be replaced after the bleaching to ensure good colour match and aesthetic result.

Don’t be alarmed if a couple of weeks immediately after the treatment, the shade may appear to relapse slightly. It is normal for this to occur and it usually stabilizes after roughly 2 weeks, with the end result lighter than the starting colour of the teeth.