An abscessed tooth is a painful infection at the root or between the gum and the tooth. It's most commonly caused by severe tooth decay. Other causes of tooth abscess are trauma to the tooth , Such as when it is broken or chipped, gingivitis, and gum disease.
These problems can cause openings in the tooth enamel, which allows bacteria to infect the center of the tooth (called the pulp). The infection may also spread from the root of tooth to the bones supporting the tooth.
Dr. James L. Johnson