A root canal is the common term for therapy that is more properly called endodontic treatment. Endodontic treatment is needed to save teeth with dying or dead pulps (nerves) because such pulps almost always become abscessed (infected). The only alternative to endodontics in treating an abscessed tooth is extraction. Many things can cause the pulp in your tooth to become diseased and die (non-vital). Dental caries (tooth decay) that has invaded the pulp most commonly does. Other causes, such as physical trauma and extensive restorations for example, can induce the nerves in your teeth to die. In most cases, an abscessed tooth will be painful and such pain is ordinarily known as a "toothache". Toothache pain comes from puss exiting the apex (root tip) of the abscessed tooth, and your body's inflammatory response to this occurrence, building pressure inside your jawbone. Nerves around the apex in your jaw bone respond to this pressure with pain, often intense pain.
When a tooth becomes abscessed the first step in treating this condition is to get rid of the infection with antibiotics such as penicillin. Novocain is generally ineffective in the presence of an abscess and so attempting final treatment of a tooth with an active abscess through endodontics or extraction is not advisable. Final treatment of an abscessed tooth requires elimination of the dead or dying pulp. While antibiotics can remove an infection, as long as its source (the dead pulp in this case) remains, the abscess will recur repeatedly. There are two ways to remove a dead or dying pulp. When a tooth is extracted its pulp is removed with it. Endodontic treatment of a tooth with a dead or dying pulp eliminates the pulp while retaining the tooth.
The tooth in this the middle of this x-ray has had its nerve irritated to death by a large filling necessitated by extensive decay.
Endodontic treatment accomplishes this latter result when the endodontist (root canal specialist) excavates the pulp from pulp chamber and pulp canals (hence the term root canal). First the endodontist isolates the rest of your mouth from the tooth and the materials and instruments used to treat it with a rubber dam. This is a sheet of latex with a hole punched into it that slips over your tooth and is held in place with a clamp on the tooth. Then an access into the pulp chamber is created with a high speed handpiece (drill) such as is used when your teeth are restored (filled or capped). Any decay present is removed during this step. Then the endodontist removes all the existing diseased nerve tissue in the pulp chamber and canals with a series of small files that increase in size. They also shape the canals to accept the endodontic filling material (called gutta percha) in the process. During this phase of endodontic treatment the pulp canals are irrigated with a disinfectant and several x-rays are taken to determine file position in your tooth. At this point the tooth is usually sealed with a temporary filling and a second appointment is made to fill the canals with gutta percha. If at the beginning of the second visit with the endodontist you report no untoward symptoms (indicating all nerve tissue is gone), your canals will be filled and the tooth resealed with a provisional filling.
The tooth was then root canalled to remove its diseased nerve and a post and core was subsequently placed prior to crowning it.
At this point the endodontically treated tooth is ready for a definitive restoration. By law, an endodontist may only place provisional restorations while treating your tooth. Anterior (front) teeth that have no or only minimal previous restorations normally can have the provisional filling replaced with a definitive one. The one disadvantage of endodontics is that teeth are hollowed out in the process of pulp removal and canal shaping making them brittle and prone to fracture. Front teeth that are more filling than tooth above the gumline and back teeth on which you do most of your chewing are at even higher risk of fracture. If a tooth fractures between its roots or too far below the jaw bone line, it becomes useless and will require extraction. Any posterior (back) tooth or an anterior one that has been extensively restored beforehand will need a post and core placed to strengthen it and then a crown (cap) cemented on it for protection. Not to do so jeopardizes the tooth as well as the time and money you have put into endodontic treatment. If you have any questions about this process, please ask Dr. McArdle