9. Why do our teeth decay?

In the case of lower animals, there is a whole succession of teeth throughout their lives. As their teeth are fully developed and used up, they fall out and new ones take their place. Only man has a single replacement of his teeth. By the time a baby is about two years old, it has total of 20 teeth, called milk teeth. Beneath these milk teeth, there is second series of teeth that begin to appear after the ago of six. The milk teeth are replaced by about the age of twelve and then more teeth appear until the adult finally has his no more chance of having new teeth, he has to keep them healthy and free from decay.

It is enamel of the teeth that becomes vulnerable to decay. For instance, when there is an invisible opening in the enamel, the bacteria in our mouth try to sneak into the cavity and they feed on the juicy dentine and the lymph that is in the dentine canals. Soon they erode the walls of the canals, and a cavity is created beneath the enamel. This may go unnoticed for some time, but if the wall of the teeth becomes thin as a result of the work of the bacteria, then we notice it very quickly, just because heat and cold can now penetrate more strongly to the pulp cavity. The pulp occupies a hollow space in the centre of the tooth and contains nerves. These nerves are stimulated by the heat or cold. When a tooth feels sensitive to heat or cold, you can be pretty sure it is a danger signal that decay is talking place.

When the bacteria penetrate through the dentine canals into the pulp cavity, they find a perfect feeding and breeding ground. Now you are in for a toothache as the decay of the tooth has already set in and the network of vessels that supply food to the teeth withers away. The tooth that is no longer nourished becomes a dead shell.

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