DENTAL CARIES
The part of the tooth called the crown lies above the surface of the gum and is covered with a coating of enamel. Fortunately, this is thickest on the grinding surface, where it wears down from use. The part of the tooth called the root that lies within the jaw is covered with a thin, bone-like layer—cementum. Beneath the enamel lies the resilient, leathery dentine, covering the pulp chamber, and running from the chamber is the root canal. The root canals contain blood vessels and nerve fibres.
It is important to realize that dental caries is a disease, not a mysterious rotting of the teeth that must be accepted fatalistically. Dental caries always starts on the outside of the teeth, in the enamel, with a pinhead-size collection of bacteria and food.
It is generally believed that most of these bacteria thrive best on starchy and sugary foods, which they change into lactic acid. Although tooth enamel is the strongest material in the body, able to withstand enormous biting pressures, lactic acid quickly and permanently dissolves it. Eating minute pits and furrows into the surface of the tooth, the acid opens up new territory for the bacteria. Soon they reach the softer, richer dentine, where they grow faster and spread rapidly. They proceed into the root canal, attacking the nerves and causing great pain. Infected pulp and decaying teeth make excellent breeding places for bacteria. They can cause localized abscesses, and may even enter the bloodstream to spread their poison to various parts of the body.
*78\68\2*
