Dental caries, also known as tooth decay or a cavity, is an infection, usually bacterial in origin that causes demineralization of the hard tissues (enamel, dentin and cementum) and
destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the tooth surface.
The progression of pit and fissure caries
Dental caries will not occur if the oaral cavity is free of bacteria. These bacteria are organized into a material known as dental plague which is yellowish coloured film on the surface of the teeth.
A variety of carbohydrates provide substrates for these organism to grow on and the waste products of their metabolism, acids, initiate the tooth decay process by dissolving the enamel surface of the tooth and create holes in the tooth (cavities). Cavities are usually painless until they grow very large and affect nerves or cause a tooth fracture. If left untreated, a tooth abscess can develop. Untreated tooth decay also destroys the internal structures of the tooth (pulp) and ultimately causes the loss of the tooth.
Caries may be curable, or not, depending on when it is found. White spots may indicate early caries that has not yet eroded through the enamel. Early caries may be reversed if acid damage is stopped and the tooth is given a chance to repair the damage naturally.
Caries that has destroyed enamel cannot be reversed. Most caries will continue to get worse and go deeper. With time, the tooth may decay down to the root. How long this takes will vary from person to person. Caries can erode to a painful level within months or years.