OVER THE RAINBOW

HOW parts of the body change colour as we age. this week: teeth turn yellow TEETH look white because they are covered with enamel, a 1.5 mm thick layer of semi-translucent material that acts as a barrier to protect the tooth. It is the hardest substance in the body.

As we age, the enamel gradually becomes stained by heavily pigmented food and drink, such as red wine, curry containing turmeric, tea and coffee.

Wear and tear on the surface — from over-brushing, teeth grinding or acidic drinks — will also thin the enamel over the years.

The more see-through it becomes, the more it will show the yellow colour of the layer underneath — the dentine.

Once the tooth enamel starts wearing at around the age of 40, the yellowing process speeds up, says dentist Tif Qureshi, of Dental Elegance in Sidcup, Kent.

‘Dentine is naturally yellow and very porous. Once it becomes exposed, it gets darker from food and drink because it’s much more absorbent than enamel.’