Root Canal, or endodontics, is the process of removing the nerves from the roots of a tooth. A root canal is often necessary to save an infected tooth. If an infected tooth is left alone for a long period of time, an abscess can form. An abscess will show up on an x-ray as a dark spot below the apex of the root. This is actually bone loss in the jaw. It is very important to catch this problem before it deteriorates too far.
There are a number of reasons why one of your teeth may need a root canal. These include but are not limited to, a very deep cavity that extends into the nerve, a trauma to the tooth that exposes the nerve, or a crack in the tooth that extends into the nerve of the tooth.