Humans have two sets of teeth in their lifetime.
Milk teeth which start to fall out around the age of five to be replaced by…
Permanent teeth which are to last for the whole of adulthood. These teeth need to be looked after otherwise they may decay or even fall out.
The different parts of a tooth can be seen in the diagram on the left.
The outer layer is called enamel. When there is sugar in the mouth this is eaten by bacteria. They form a sticky substance called plaque that produces an acid which weakens the teeth and leads to tooth decay.