What is white?

Teeth are never white!

Colour perception varies from person to person and is dependant not only on the object colour but also on the surrounding colour. Darker lips or skin makes teeth look whiter.
The surface texture affects the reflection and refraction of light and again can influence colour perception. This can have more effect than the actual body colour of the teeth.

The structure of teeth is an internal pulp made up of blood vessels and nerve tissue (red/pink in colour) surrounded by dentine, which varies from yellow to brown.
The dental enamel covering the tooth is a crystalline structure of off white interspersed with chemical discolouration incorporated into the enamel while being formed in childhood from natural chemicals in the water, from food, from medicines and from natural processes and interaction between foetal and maternal blood during pregnancy. Enamel is layered and under a microscope looks similar to tree rings, and can show the same sort of information from its development stages.
The translucency can vary enormously and the denser (and stronger) the enamel, the more translucent it is, and therefore the more the darker colour of the dentine will show through.
As enamel wears, with age and use, it becomes thinner and again shows the dentine more, looking darker.
Age and use creates microscopic and macroscopic cracks in the surface of the enamel and these cracks trap staining from food and drink. Because this is below the surface of the enamel it is not removed by normal cleaning.
The more you brush your teeth, the quicker the enamel wears and the darker the teeth become.

What can be done about it?

General cleaning

1. Teeth should not be over cleaned. Proper cleaning once or twice a day is adequate along with flossing between the teeth.
2. Lightening toothpastes have only a marginal intermittent effect.
3. The dental hygienist can remove the surface tartar that builds up and gets stained.
Clinical intervention
1. Bleaching the teeth can lighten the shade of the teeth. It will need topping up from time to time.
2. Certain types of discolouration will not respond to bleaching, or have limited response.
3. The lighter the teeth are already, the smaller the effect of bleaching.
4. Stained micro-cracks respond very well to bleaching.
5. Crowns and white fillings don’t respond to bleaching.
6. Abrasive toothpastes (like smokers toothpaste) wear the enamel and eventually make the teeth look darker (see above).
7. In more severe cases porcelain veneers can be bonded to the front surface of the teeth. (See information sheet 24) Veneers may need replacing after 10-12 years if the gums shrink back too far.
8. On back teeth it may be necessary to crown the teeth, as veneers are not strong enough for these teeth.