A Root canal is the process of removing the dental pulp (tooth nerve tissue and blood supply). When tooth decay reaches the nerve of the tooth, it can cause terrible pain to hot and/or cold. The bacteria that causes decay can reproduce inside the tooth and cause an infection that extends down the roots of the tooth into the bone around the tooth. This can be a common cause of pain upon biting. Once the root(s) of the tooth are cleaned out and disinfected, the source of the infection is gone, the body is able to fight off the remainder of infection, and the pain soon disappears. The root is sealed off with gutta percha (a rubbery material that seals the canals) and the hole in the top of the tooth is patched w/ filling material (composite or amalgam buildup) To prevent bacteria from entering into the tooth again. It is highly advised to crown posterior teeth after root canal to prevent fracture of the tooth.