Tooth decay is perhaps the most common dental disease across all age groups. The mouth is always home to huge numbers of bacteria (more than 5 million in each cubic millimeter of saliva!). Dental caries (decay) is a sugar-dependent disease where the bacteria consume the sugar to produce acid which in turn dissolves enamel and dentine, leading to caries. Some natural repair of the damage occurs between exposure to acid, but frequent exposure or prolonged exposure through sticky foods or poor oral hygiene will accelerate the process of decay. This begins as a small white spot on the external surface of the tooth and turns brown or black. Your dentist will look for this during a routine dental check-up. You may experience an increased sensitivity to hot and cold beverages and with sugars. Your dentist can remove the decay and restore the lost structure with various types of filling material.
Ultimately, the decay and damage reaches the pulp space containing nerves and blood vessels and there is acute pain. Infection may spread to the underlying supporting structures of the tooth socket and the jaw bone, resulting in an abscess. In these circumstances the tooth needs root canal treatment before restoration of lost structure.