Root Canals

A popular illustrated history of dentistry explains that people of ancient times believed that the toothworm "had appeared spontaneously or had bored its way into the mouth." If the pain was unbearable, author Loretta Ichord wrote, "it meant the worm was thrashing about; but if the aching stopped, then the worm was resting." After Fauchard extracted the pulp and "root" of an infected tooth to ease a patient's pain, he examined them under a microscope. After many such investigations, he reported that he had never found a toothworm.

Root canal surgery has come a long way since then, although some popular misconceptions remain. One common belief is that if a tooth is badly infected, the best treatment is often to have it pulled. But these days, dentists and dental surgeons say that it's far better to keep a tooth than to extract it. Nothing can ever completely replace a natural tooth -- especially since artificial teeth can be difficult to keep clean, according to the American Association of Endodontists, a trade group for dentists who specialize in root canal therapy. In addition, the association notes, many teeth with root canal treatments can last a lifetime.

How does the tooth's core get infected?

Teeth can become infected when plaque erodes the tooth's outer enamel, allowing bacteria to infiltrate. This can also occur when a tooth is cracked or damaged -- or equally important, when an artificial crown develops a small crack. If a filling is loose, or, in rare cases, a cavity isn't properly cleaned before a filling is inserted, the resulting bacteria can infect the tooth's core in the months following the procedure. When a tooth's nerve center is badly infected, the core (pulp) usually has to be removed.

What are the symptoms of this infection?

Many people feel pain when they eat hot or cold foods. The pressure of biting and chewing can also be painful, a sign of a serious infection.

If you have a toothache, see your dentist right away. You may only need a filling, but you should have it checked out as soon as possible. Without treatment, the infection will eventually spread and the tooth may fall out.

How long should I wait to see a dentist?

It's good to see a dentist every six months, because they can usually catch problems before something like a root canal becomes necessary. Make an appointment if you notice brown spots on your teeth or a hole in a tooth or filling. Anytime you feel pain in your tooth or jaw, though, see your dentist immediately. It's risky to wait until you have the stabbing pain of a severe toothache.

In rare cases, an infection can spread to the bone beneath the tooth, which could involve more serious surgery. If the infection spreads to the neck, it could cause a life-threatening swelling.

What is a root canal treatment?

Root canal treatment is the preferred way to treat an infection in the nerve center of the tooth, known as the pulp. The pulp is the soft, inner core of the tooth that consists of blood vessels, nerves, and connective tissue. Infection occurs when a breakdown of the hard outer part of the tooth (the enamel) allows bacteria to erode the next layer of the tooth (dentin) and reach its sensitive core.

What takes place during a root canal?

The dentist cleans the diseased pulp tissue and bacteria and flushes the tooth out with water. After being cleaned thoroughly, the hole is slightly enlarged so that it can be fitted with a temporary filling. However, the hole may not be filled and sealed until all signs of infection are gone. In the meantime, the temporary filling will allow the tooth to drain and heal. Your dentist may want to see you for one or more visits to check your tooth before you get a permanent filling.

When you're ready for a permanent filling, the temporary filling is removed and replaced with rubberlike material and a sealant. The doctor may place a crown made out of metal, such as gold, or porcelain on top of this filling. When a root canal is performed on teeth behind the molars -- the teeth in the back of the mouth used for chewing -- the dentist may also fit a crown over the tooth to stabilize it.

Are there any risks associated with root canal treatment?

Very few. About 95 percent of root canals are successful and the pain does not return. However, sometimes a root canal needs to be redone if some of the infected pulp was not entirely removed.

The fillings used today are also safer than they used to be. Your dentist will probably use gutta-percha, a resin from the Isonandra Gutta tree found on the Malay Peninsula, to fill the cavity and permanently seal the root canal. Gutta-percha is a rubberlike, waterproof substance that was used to lay the first transatlantic telegraph cable before the invention of plastic.

Some substances once widely used to fill the pulp cavity are no longer recommended. The American Association of Endodontists, for example, recommends against the use of paraformaldehyde (also called N2 or Sargenti paste) because it may damage tissue and bone and infiltrate the blood.

Do I need to take antibiotics when I get a root canal treatment?

Patients with valvular heart disease or heart murmurs may be advised to take antibiotics as a preventive measure against infection when undergoing a root canal treatment (or any major dental procedures). That is because bacteria from the mouth can spread to the blood during a dental procedure, and in rare cases can stick to the heart valves and cause a serious infection known as endocarditis. If you have been diagnosed with this type of heart disease, talk to your doctor or notify the dentist or endodontist performing the procedure. You may also get antiobiotics if the root is infected and the infection has spread beyond the roots.

Does root canal treatment hurt?

The treatment should be as painless as getting a cavity filled, according to the American Association of Endodontists. In fact, people usually see the dentist because they're already in severe pain. You'll be given a local anesthetic to make the area around the affected tooth as painless as possible

Root canal treatment has become increasingly sophisticated in recent years, particularly since dentists have begun using surgical operating microscopes that make it far easier to trace the paths of root canals. But if you're still concerned about pain, talk to your dentist about how much pain makes you uncomfortable. Your dentist may be able to adjust the amount of anesthesia or give you nitrous oxide to make you more comfortable.

References

Interview with Christopher Wenckus, chairman of the Department of Endodontics at the University of Illinois at Chicago

Interview with Dr. Samuel Dorn, the outgoing president of the American Association of Endodontists

Myths About Root Canal Treatment, American Association of Endodontists

Root Canal, Academy of General Dentistry http://www.agd.org/consumer/topics/rootcanaltherapy/main.html

Getting to the Root of Endodontic (Root Canal) Treatments, American Dental Association http://www.ada.org/prof/pubs/jada/p-page/p-page5.

What is a Root Canal? Academy of General Dentistry. http://www.agd.org/consumer/topics/rootcanaltherapy/main.html

American Association of Endodontists. Concerning Paraformaldehyde-Containing Endodontic Filling Materials and Sealers. http://www.aae.org/NR/rdonlyres/14F3726F-DA2D-4155-97E9-D0201E690B17/0/paraformaldehydefillingmaterials.pdf