Root canal procedures, which are done to treat infections and inflammation inside teeth, have a reputation as being very painful and, as such, are often evoked in reference to unbearable situations in daily life. You may recall, for instance, the case of Education Secretary Betsy DeVos: After she went through her contentious confirmation hearing before Congress back in 2017, she compared the experience to undergoing a root canal (though she never had one herself). Just the idea of having this treatment makes many people break into a sweat but, in reality, local anesthetics are effectively used, making any discomfort not so different from simply having a cavity filled.
According to the American Association of Endodontists, more than 15 million root canal procedures are performed a year in the U.S., either by a general dentist or by an endodontist, a dentist who specializes in the treatment of the interior of the tooth (the dental pulp). The word endodontist is derived from Ancient Greek, with “endo” meaning “inside” and “odont” meaning “tooth” or “teeth.”
The root of the problem
In brief, the procedure involves removing the soft dental pulp from a tooth, cleaning out the inside of the tooth (including the pulp chamber and associated root canals), and then filling and sealing up the space. This pulp, which extends from the top (crown) of the tooth (beneath the enamel and dentin) to the very bottom or tips of the roots, contains blood vessels, connective tissue, and nerves. A root canal procedure is done when the pulp has become irreversibly infected or inflamed due to deep decay or some type of damage to the tooth. Basically, it saves a tooth that would otherwise have to be extracted and typically replaced with a dental implant—a more costly and involved process—or with a bridge.
Note that the term “root canal” can refer to both the dental procedure and a part of the tooth’s anatomy, though dentists tend to refer to the latter simply as “canals.”
Infection or inflammation inside the tooth—and thus the need for a root canal—can result if you have had repeated work on a tooth; a filling or previous restoration has failed; a tooth has chipped or fractured; or a tooth was traumatized without being fractured. You may know you need the procedure if you have prolonged sensitivity to heat or cold in the tooth, the color of the tooth changes (to gray), you have pain or discomfort (including during chewing), or there’s gum swelling (abscess) near the tooth. The lymph nodes in the neck may also become swollen or tender.
On the other hand, damaged pulp and canals can sometimes calcify on their own. In such cases, if there is pain or other symptoms or signs, a root canal is not possible and a different procedure (apicoectomy, which removes the tip of the tooth’s root) might be needed instead.
Before a root canal, X-rays are taken to confirm the need for the procedure and to identify the structures involved. (X-rays are also usually taken during the procedure to assess progress.) The procedure itself involves several steps, typically done in one or two sessions. After a local anesthetic is given, a rubber sheet (called a dental dam) should be placed in the mouth to cover and protect the area around the tooth. This prevents bacteria in saliva from entering the tooth’s interior, gives the dentist good visibility, and assures that the tiny instruments or filling materials used during the procedure don’t get swallowed or go down the windpipe.
The American Association of Endodontists considers dental dams essential, but according to a 2015 study in BMJ Open, only 47 percent of dentists always use one during a root canal procedure.
The dentist begins by drilling into the tooth to access the pulp chamber and associated canals. The pulp is then removed and the pulp chamber and canals are smoothed and enlarged using small metal files. This part of the procedure also involves flushing the area of the diseased or dead nerve tissue and any bacteria that may be present, using various chemicals.
The pulp chamber and the canals are then filled—typically with gutta-percha (a biologically inert material) along with an adhesive cement—and then sealed with a temporary filling or temporary crown (cap) until a permanent crown is later made, or with a permanent filling if no restoration is needed. Sometimes a permanent post is inserted into the tooth before the tooth is sealed to provide additional support for a future crown.
A crown is put on the tooth after a root canal because removing the pulp makes the tooth more fragile and likely to break or fracture over time—though one may not be needed on a front tooth. Molars are especially weakened because they are put under a lot of stress during chewing of food, compared to other teeth. The restoration, typically done by a general dentist, should be started as soon as possible, preferably within a few days.
Root Canals Through the Ages
Dental anthropologists have traced what may be the oldest root canal procedure to an ancient Roman soldier living in the Negev Desert (present-day Israel) in the 2nd or 3rd century B.C.
Many root canals will last a lifetime. But they can also fail months or years later, meaning that inflammation or infection has developed inside the tooth again. This can occur for several reasons—for example, if the root canal procedure wasn’t done completely (perhaps because the curvature or narrowness of the canals made this difficult or impossible) or if the tooth didn’t heal well after the procedure.
Failure may also occur if a crown was not put on the tooth or was put on too late, resulting in the tooth fracturing and becoming infected. New decay can also infiltrate the tooth if the crown didn’t adequately protect the tooth from bacteria or if good dental hygiene was not practiced.
Or there may have been a new trauma to the tooth. Another root canal procedure may be needed at that point, which may involve removing the crown, repeating the procedure, and then usually making a new crown afterward. A tooth can also fracture after a root canal, even if the crown was done right, necessitating extraction of the tooth, after all.
Also see Your Dental Checkup.
Published December 09, 2019