Now researchers have invented a material which could help people regrow their own tooth enamel naturally.

When people eat too much sugar they get holes in their teeth where the enamel coating the outside is decayed.

The only answer is in the dentist's chair, where the hole is plugged using a cement or resin filling, which can lead to a potential infection or need to be replaced several years later when it becomes loose.

For more than a decade scientists have been trying to replace fillings by making tooth enamel regrow, by providing it with extra calcium phosphate. 

The problem was that the new enamel did not have the right 'fish-scale' structure and consequently was too soft.

But now scientists have used extra tiny clusters of calcium phosphate which organise into hard enamel within hours.