Trauma to a tooth, by injury or decay, can result in an infection of the pulp (nerves & blood vessels) of the tooth. It is possible for this to happen even if the tooth doesn’t have a cavity. The tooth may be extremely painful if the infection is unable to drain because pressure builds up inside the tissue causing swelling of the face, or sometimes a small pimple like lesion on the tissue.
In other instances the tooth may die and no longer be painful. The infected tissue will then rot and breakdown from the inside. If left untreated the tooth will eventually turn black, become brittle and eventually break.
Neither situation is healthy. The diseased tissue should be removed. Sometimes antibiotics will also be prescribed to eliminate the infection that has spread into the tissue.
A root canal, also called endodontic therapy, removes the dead/dying nerves and blood vessels and infection from inside the tooth. The space is then backed with a plastic filling material and restored.