Pain localized to a tooth is referred to as a toothache. The most common cause of toothache is a cavity (caries). Cavities are areas of damage to the tooth that result from destructive enzymes which combine with bacteria and plaque to wear away the minerals of the tooth. Cavities usually start at the outer surface of the tooth called the enamel.
The treatment of cavities includes avoiding sweets and extremes of hot and cold which can provoke the pain. Medications, such as acetaminophen (Tylenol), can help relieve pain. Patients should then seek the help of a dentist. A simple filling repair may be the best ultimate treatment.
The treatment of dental and medical conditions changes substantially through the centuries. Let us hope for the better!
Two hundred years ago this was how practitioners in England (a center of sophisticated medical care at the time) treated toothache:
"In order to relieve the tooth-ach, we must first endeavour to lessen the flux of humours to the part affected. This may be done by mild purgatives, scarifying the gums, or applying leeches to them, and bathing the feet frequently with warm water. The perspiration ought likewise to be promoted, by drinking freely of weak wine-whey, or other diluting liquors with small doses of nitre."
(Source: Domestic Medicine for the use of the private practitioner by William Buchan, M.D.; 1828)