Teeth Whitening

The outer layer of a tooth is called the enamel. The color of natural teeth is created by the reflection and scattering of light off the enamel, combined with the color of the dentin under it. Your genes affect the thickness and smoothness of the enamel. Thinner enamel allows more of the color of the dentin to show through. Having smoother or rougher enamel also affects the reflection of light and therefore the color.

Every day, a thin coating (pellicle) forms on the enamel and picks up stains. Tooth enamel also contains pores that can hold stains.

The most common reasons for teeth to get yellow or stained are:

• Using tobacco
• Drinking dark-colored liquids such as coffee, cola, tea and red wine
• Not taking good care of your teeth

Aging makes teeth less bright as the enamel gets thinner and the dentin becomes darker.

It is also possible to have stains inside the tooth. These are called intrinsic stains. They can stain a child's teeth if taken by a mother during the second half of pregnancy or by a child who is 8 years old or younger. Teeth are still developing during these years. Trauma may also darken a tooth.

The most common type of tooth whitening uses a gel that is applied directly to the tooth surface.

Tooth whitening can be done in the dentist's office or at home.

In-office whitening allows your dentist to use a more powerful whitening gel. A specialised light or laser activates the gel and allows bleaching to happen faster.

In-office whitening usually takes 30 to 90 minutes. You will need 1 to 3 appointments. The number will depend upon the method used, how severe your stains are and how white you want your teeth to be. Different types of stains respond differently to the treatment.

For in-home whitening, your dentist will take impressions of your upper and lower teeth and will make custom mouthpieces to fit you. At home, you will fill each mouthpiece with a whitening gel your dentist provides. You will wear the mouthpiece for several hours every day. Many people achieve the amount of whitening they want within a week.