Root canal treatment is a set of complex procedures designed to treat problems that arise from inside the tooth. With the new techniques in anesthesia, in most cases this procedure is not any more uncomfortable than a filling. It's actually one of the most effective ways of relieving some kinds of tooth pain.
A root canal procedure becomes necessary when a tooth becomes infected or inflamed by decay or trauma to the tooth. A deep cavity may penetrate the pulp tissue (blood vessels and nerve cells) causing intense pain that may not go away. The infection will remain without treatment, leading to a dental abscess and may lead to problems in other areas of the body.