When you have an abscessed tooth, it means you have a pocket of pus, normally caused by some kind of infection, and bacteria has spread from the root of the tooth to the tissue just below or near it.
Generally speaking a tooth that has become abscessed means that the underlying pulp or tooth’s soft core has become infected and swollen. The pulp contains blood vessels and connective tissue, and lies within the tooth. It extends from the crown of the tooth, to the tip of the root, in the bone of the jaws.
You may be experiencing extreme pain if you have an abscessed tooth. In some cases, antibiotics are administered in an attempt to kill the infection. If that fails and the abscess is shown to be damaging the pulp or the bones below, a root canal procedure may be needed to remove the dead pulp and restore the tooth back to a healthy state.