Root canal treatment (also referred to as root canal therapy or endodontic therapy) is necessary when the pulp, the soft tissue inside your teeth containing blood vessels, nerves and connective tissue, becomes inflamed or diseased. Most commonly when a cavity is allowed to reach all the way to the pulp. (regular cleanings and checkups can help prevent and detect problems early).
Sometimes deep restorations or trauma to a tooth may cause the nerve to be damaged to the point it needs root canal therapy. Once this occurs the pulp becomes infected and can even extend through the root tip and begin to eat away at the surrounding bone.
In cases such as this, the nerve and the pulp, the soft tissue inside the tooth, will have become damaged and will have to be removed in order to prevent the infection from spreading and the tooth being fatally compromised.
During root canal treatment, your dentist or endodontist (a dentist who specializes in treating the insides of teeth) removes the diseased pulp. The pulp chamber and root canal(s) of the tooth are then cleaned and sealed with a special material. If the infected pulp is not removed, pain and swelling can result, and your tooth may have to be removed. Although complex in nature, it is a treatment which can save an otherwise badly stricken tooth.