Teeth whitening procedures are among the most popular cosmetic dental procedures because they can greatly enhance the appearance of your teeth. What is tooth whitening? Teeth whitening lighten the teeth and help to remove stains and discoloration from the inside of the tooth structure. How does teeth whitening work? The colour of natural teeth is created by the reflection and scattering of light off the enamel (outer layer of the teeth), combined with the colour of the dentine (layer underneath the enamel). This is affected by the thickness of the enamel and the darkness of the dentine. Aging makes teeth less bright as the enamel gets thinner and the dentine becomes darker. It's advised that external staining from tea, coffee, red wine and tobacco is removed before the whitening process, because the whitening process will only have an effect on the dentine (layer underneath the enamel).