All about face > Teeth file > Teeth colour

Teeth colour is determined by your genes. Ethnic background makes no difference, though darker skin makes teeth look brighter. There are 28 naturally occurring shades of teeth, ranging from butter yellow to grey. Most people are born with ivory-coloured teeth – in dentist's jargon, around an "A2". This shade is seven steps away from the apex of whiteness, a B1. Even B1 has shades of yellow, however, because natural teeth are never pure white. Only Americans tend to aspire to the artificial range of 040, 030, 020 and purest white, 010.

Teeth tend to get yellowed with age, and staining can cause the surface to discolour. Tea, coffee and red wine all stain the teeth. Smoking gradually turns them brown.

Tooth whitening means that it is possible to permanently lighten the colour of the teeth, whatever your age. The end result can be up to six shades lighter than your original colour. The most common method uses a solution of hydrogen peroxide to bleach the dentine, which is the pulpy layer beneath the enamel.

"Enamel is translucent, so the colour of teeth is determined by the dentine underneath," explains Jo Tanner, of the British Dental Association. "Enamel is porous, so the bleach can penetrate right through."