This illustration shows the anatomy of a tooth and gums as well as the supporting structures that surround a tooth. The left side shows healthy gums and bones and the right side shows unhealthy supporting structures.
Not all teeth have one root. For example: the molars on the top arch have three roots, whereas, the molars on the bottom arch have two roots.
An infected tooth as seen in an x-ray.The dark circle around the root tip is an advanced dental abscess. If the tooth is infected, why can’t I use an antibiotic to treat it?
If a tooth has an infection of the pulp, the only options are root canal therapy or extraction. As the pulp dies, the hollow tooth becomes a reservoir for bacteria to hide from the body’s immune system and any drugs that could fight the infection. In some cases a dentist will prescribe antibiotics during or after root canal therapy to kill bacteria within the jawbone and tissues surrounding the tooth, but recent research has shown that this is usually unnecessary.
What’s involved in getting a root canal, and does it hurt?
Root canal therapy is a complex procedure that requires both skill and experience. The dentist numbs the area of the infected tooth with local anesthesia. A clamp is placed over the tooth, and a rubber membrane (rubber dam) is spread over the clamp to isolate the tooth and prepare it for the operation.
An infected tooth.
A small hole is made through the enamel and dentin, and into the pulp. The pulp is then removed with small stainless steel files of increasing diameter. After the pulp has been removed, the inside walls of the roots are shaped, almost like a sculpture. Nickel/Titanium files that fit on a slow speed drill can aid in shaping the canals. During the procedure, fluids (irrigants) such as sodium hypochloride (bleach) and a compound containing ethylenediamine-tetraacetate (EDTA) are used to both kill remaining pulp tissue and bacteria within the roots, and remove dentin shavings produced by the files.
Files are used to remove the pulp.
After the pulp is removed and the inside of the roots shaped, the canal is dried with paper cones. The canal(s) are then filled with Gutta-percha. Gutta-percha is a miraculous substance that was first introduced by Bowman in 1867. It is a purified form of Mazer Wood Trees indigenous to Indonesia and Malaysia that is combined with zinc oxide and other materials to form the rubbery filling that is placed into the tooth roots. The Gutta-percha is then cemented into the roots with a sealer that usually contains zinc oxide and eugenol. The goal of the filling procedure is to hermetically seal off the tooth against bacteria.
The tooth is filled with gutta-percha.X-ray of a tooth filled with gutta-percha using the horizontal condensation technique. Accessory canals are visible.
Root canal therapy is usually not painful. With the effective use of anesthesia and modern techniques, most root canal therapy can be completed in one visit, and within one hour. A tooth will be sensitive for a few days after root canal therapy, and your dentist can prescribe you medication to alleviate the pain. In the meantime, do not eat on the side of the mouth that has the root canal for a few days.
Do different teeth have different numbers of root canals?
Teeth in the front of the mouth called incisors and canines usually have one root, and one nerve canal within the root. Teeth on the side of the mouth called premolars usually have one or two roots and one or two root canals. The upper back teeth (molars) usually have three roots, and three or four root canals. Lower back teeth (molars) usually have two roots and three or four root canals. Generally speaking, the more nerve canals the tooth has, the more complicated the root canal is to complete.
Can any dentist do a root canal treatment?
All dentists are trained to do root canals in dental school; however, skill levels and experience vary widely from dentist to dentist. An experienced general dentist can do almost all root canal therapy successfully.
How successful are root canal treatments?Root canals are successful about 90% of the time when they are done properly. Teeth that have had root canal can become brittle and are susceptible to fracture. In most cases, it is advisable to have a crown (cap) placed over a tooth that has had root canal to rebuild and protect it.
Why do some root canals fail, and how will I know?
A tooth that has root canal can fail if some of the pulp is left inside the roots (a canal is missed), the gutta-percha does not completely seal off the tooth from bacteria, the tooth is damaged during the procedure (perforation), or the tooth fractures between the roots. In most cases, a tooth with a failing root canal will cause pain, usually when biting down.
What can I do if the root canal fails?
In some cases, the root canal can be re-treated. The old gutta-percha filling is removed, the tooth is reshaped and cleaned, and then re-filled. If this is not possible, a procedure called an apicoectomy can be preformed. In an apicoectomy, the tip of the root is surgically removed, and a filling is placed over the cut root tip. If these measures fail, the tooth may have to be extracted.