Teeth whitening involves bleaching the teeth to lighten their color. After treatment, the teeth look a few shades whiter, but not usually bright white.
Whitening products typically use the chemicals hydrogen peroxide or carbamide peroxide. Only registered dental practitioners can legally use the most concentrated — and thus most effective — whitening solutions.
The bleach soaks through the tooth’s enamel top layer and into the dentine, the main part of the inside of the tooth which is slightly softer than the enamel. The bleach reacts with the coloured molecules that cause discoloration. The dentine then becomes lighter and the teeth look whiter. Bleach can also make the enamel surface more reflective, which looks whiter too.
Teeth can be discolored by:
- tea, coffee, red wine or cola
- excessive fluoride or tetracycline (an antibiotic) when the teeth are forming
Teeth whitening is not recommended if you:
- are pregnant or breastfeeding
- have sensitive teeth
- have gum disease or shrinkage
- have cracks or exposed dentine
Whitening is generally successful and can last for several years, but it isn’t permanent: for example, tea, coffee and red wine can stain your teeth again.
If you’re not happy with your teeth, alternatives include:
- having your teeth cleaned by the dentist
- using whitening toothpaste
- dental restoration, such as veneers or crowns