4. Crowns or caps

What are they for?: Used to restore chipped or replace broken teeth.

How they work: An impresion of the tooth is taken and the crown - made from metal or porcelain - is built in a laboratory to individual prescription, using a gold alloy covered with bonded porcelain. The old tooth is then cut down a millimetre or so to make room for the crown. The crown is then cemented on to the tooth.

How long does it take?: Two two hour appointments.

How long does it last?: Permanent.

Cost: A crown costs from £400 each.

Stars who have opted for this treatment are Kelly Brook, Kate Winslett, Daniel Craig

Britney Spears