Endodontic therapy or root canal therapy is a sequence of treatment for the infected pulp of a tooth which results in the elimination of infection and the protection of the decontaminated tooth from future microbial invasion. Root canals and their associated pulp chamber are the physical hollows within a tooth that are naturally inhabited by nerve tissue, blood vessels and other cellular entities which together constitute the dental pulp.Endodontic therapy involves the removal of these structures, the subsequent shaping, cleaning, and decontamination of the hollows with small files and irrigating solutions, and the obturation (filling) of the decontaminated canals with an inert filling such as gutta-percha and typically a eugenol-based cement. Epoxy resin is employed to bind gutta-percha in some root canal procedures.
In the situation that a tooth is considered so threatened (because of decay, cracking, etc.) that future infection is considered likely or inevitable, a pulpectomy, removal of the pulp tissue, is advisable to prevent such infection. Usually, some inflammation and/or infection is already present within or below the tooth. To cure the infection and save the tooth, the dentist drills into the pulp chamber and removes the infected pulp and then drills the nerve out of the root canal(s) with long needle-shaped hand instruments known as files (H files and K files). Starting with a smaller file size (sometimes termed a ‘pathfinder’), progressively larger files are used to widen the canals. This process serves to remove debris and infected tissue and facilitates greater penetration of an irrigating solution (see ‘irrigants’ below). After this is done, the dentist fills each of the root canals and the chamber with an inert material and seals up the opening. This procedure is known as root canal therapy. With the removal of nerves and blood supply from the tooth, it is best that the tooth be fitted with a crown.