Summary : This section outlines the process of tooth decay and the subsequent damage to the tooth. Decay can occur quickly when a lot of sugar is eaten and may infect and kill the nerve inside.
When decay first starts it only involves the enamel which coats the outside of the tooth. The damage to the enamel is somewhat reversible. Flouride toothpaste helps in this way as the fluoride becomes incorporated into the surface of the tooth which is more resistant to decay.
If the patients diet doesn't change, then the decay will continue until it reaches the dentin. Dentin is a lot weaker than enamel and once damageis caused, it is very difficult to reverse. At this point a filling will be needed in the tooth. Decay underneath the enamel may appear as dark shadowing or a stain like appearence.
If the tooth is left untreated, things will only get worse. The hole will fill with plaque, bacteria and food debris. Bacteria may pass through the dentin towards the nerve and may infect it and cause an abcess.
Enamel is very brittle and once the dentin underneath is destroyed by decay the enamel may colapse leaving a large hole in the tooth. If teeth are left in this state there is a high risk of nerve death and/or gross destruction of the crown.