The structure of your teeth

Every tooth is made up of two main layers. The inner layer is made from a material called dentin, a calcified body tissue which is made up of microscopic channels which penetrate all the way to the outer layer, the enamel. The enamel is the hard outer layer which shields your teeth. As you eat and drink another layer is gradually formed over the top of your enamel (known as a pellicle film) and certain foods and drinks such as red wine, tea and coffee have been shown to increase the rate of discolouration. It's possible for this layer to be cleaned by brushing your teeth, scraping or certain chemical procedures. There's two main types of stain, Extrinsic stains appear mostly on the surface of teeth and can usually be brushed away initially. Intrinsic stains are stains which form inside the tooth and gradually appear on the outside. However the big problem is that the materials in your food and drink which cause the staining can penetrate through the porous enamel to where they can't be scraped or scoured off and this is where tooth whitening comes in.

How does the procedure work?

The most common form of tooth whitening is bleaching performed under the supervision of a dentist. This is where chemicals are applied which can penetrate into your enamel and create a chemical reaction which works to dissolve the materials which cause the discolouration. The most popular chemicals used in tooth whitening include hydrogen peroxide and carbamide peroxide. Before applying the chemical your dentist will usually give your teeth a thorough cleaning and examine the rest of your mouth to check for cavities and any gum infections. A protective barrier is usually put in place to protect your gums which could potentially be damaged or burnt. The compound will then be pasted on your teeth where it will remain for several minutes. After this the paste is rinsed off and the procedure repeated a number of times. Significant results can be achieved by this method after only one treatment.

It's also possible to use professionally dispensed whitening kits in the comfort of your own home. Through constant use home whitening kits can produce excellent results, especially when used in conjunction with in-office whitening treatments. The kits usually contain a low concentration peroxide gel which you place on your teeth. How long the gel is left on for depends on the concentration and some kits can be used overnight whereas others need to be removed within an hour. The gel is applied through the use of a bleaching tray which looks similar to a gum shield used in sports. Similarly over-the-counter kits have become popular in recent years for their ease and effectiveness. These treatments use a one-size-fits-all mouth tray and a low concentration gel designed to concentrate on the front teeth which show when you smile. Due to the low concentration involved in this method it may take a few months for results to become noticeable.