Endodontics, from the Greek endo (inside) and odons (tooth), is one of the nine specialties of dentistry recognized by the American Dental Association, and deals with the tooth pulp and the tissues surrounding the root of a tooth. If the pulp (containing nerves, arterioles and venules as well as lymphatic tissue and fibrous tissue) has become diseased or injured, endodontic treatment is required to save the tooth. Endodontic therapy involves the complete removal of everything that lies in the root canal. The hollow area is then cleaned, shaped and decontaminated. Miniscule files and irrigation solutions are used. An inert filling, such as gutta percha, fills up the hollow, along with a eugenol-based cement. After endodontic therapy the tooth is dead. The patient will no longer feel any pain on that tooth because the nerve tissue has been taken out and the infection has been eliminated.