Root Canal Procedure


During a root canal, your dentist cleans out the interior of the tooth, shown here in a cross section.
During a root canal, your dentist cleans out the interior of the tooth, shown here in a cross section.
©Ethan Janson/Getty Images

Guess how many American adults have had tooth decay in their permanent teeth. One third? One half? In fact, 92 percent of Americans ages 20 to 64 have had a cavity as an adult, and just shy of a quarter of that age group have untreated tooth decay [source: NIDCR].

Tooth decay is, undeniably, a common problem. While surface decay can usually be treated with a filling, a tooth with deep decay -- or one that has been severely injured by accident or the trauma of recurrent dental work -- may become unhealthy, inflamed or infected. Left untreated, an infection may spread to the surrounding tissue and an abscess may form.

While there was a time when there was no other choice than to pull a dying tooth, dentists today try to help patients keep their natural teeth for as long as possible. One of the most common dental procedures is intended to give a tooth a second chance by treating the inflammation and infection from the inside: the root canal procedure. During a root canal procedure, decay is removed, the inside of the tooth is cleaned and filled, and the outside of the tooth is sealed and capped. Before we can really understand how a root canal is performed and why, let's first get comfortable with a few basics of a tooth's anatomy.

The crown of the tooth is the part that you see inside your mouth. The root of the tooth is below the gumline. The pulp is the innermost part of a tooth. It's found in the pulp chamber inside the crown of the tooth as well as in the root canal that extends from the tip of the tooth into the pulp chamber. The pulp is made up of nerves, blood vessels and connective tissues -- it's the living part of the tooth.

Root canal procedures save teeth. There are more than 15 million root canal procedures performed every year in the United States, and while your dentist is trained and capable of performing a root canal, some patients choose to have an endodontist perform the procedure [source: American Association of Endodontists]. An endodontist is a dentist who specializes in treating the inside of teeth.

To determine whether or not root therapy is needed, the dentist will first assess the patient's symptoms. Tooth ache or pain, tooth darkening or discoloration, a tooth that has developed a prolonged increase in hot/cold sensitivity and pain, or tenderness when a tooth is touched or while chewing (although some people report little to no pain) are all signs the nerve may be damaged.

While a root canal is tailored to the patient's specific dental health needs, we'll cover the basics common in every root canal procedure. Even if there is no associated pain, an unhealthy tooth needs to be treated -- while an inflamed pulp may sometimes heal on its own, an infected pulp can die without treatment, toothache or not. Let's look at what root canal treatment involves, from diagnosis to done, beginning with measuring and cleaning the inside of the tooth.

Measuring and Cleaning Root Canals

Over the course of one to three visits, the dentist will diagnose the problem, determine whether or not root canal treatment is the correct form of therapy and, if needed, perform the procedure.

The first step toward diagnosis is an external (face and neck) examination to assess for any swelling, tenderness or enlarged lymph nodes. Next is an internal (inside the mouth) examination to assess the patient's overall oral health and hygiene.

The dentist will also take x-rays of the affected tooth to help analyze its health. While an x-ray offers a good look at the affected tooth's size, shape and surrounding tissue -- information that's necessary while performing a root canal procedure -- the dentist will also use those x-rays to look for two specific things to help with diagnosis: enlargement of the periodontal ligament and the presence of a dark area at the root tip, two determining factors of an infection in the pulp chamber.

Additionally, the dentist will determine how healthy the pulp of the tooth is. Pulp testing may be done in a few different ways. The dentist may gently tap a finger against the tooth to assess for sensitivity and tenderness. Electric pulp testing (EPT) or thermal pulp testing may also be conducted. EPT is a painless way in which to test the health of the pulp, and it works by sending a gentle pulse of electricity into the tooth to test the life of the nerve tissue. Thermal pulp testing involves applying either hot or cold stimulus to the tooth to see if the tissue responds to stimulus.

With diagnosis complete, the first step in a root canal procedure is -- you can relax -- administering local anesthesia. A sheet of latex (also known as a rubber dam) is placed around the affected tooth to isolate it from other teeth and to keep the area clean and saliva-free during the procedure.

With the prep done, it's time to remove some decay. The dentist will drill a small opening in the top or the back of the tooth -- this is the access hole to the pulp chamber -- and will begin to remove decaying tissue. Before they can be cleaned thoroughly, though, the canals inside the tooth need to be measured.

Dentists use a few different methods for measuring canal depth, including diagnostic x-rays, radiographic techniques (x-rays taken during the procedure) and a specialized tool called an apex locator, which uses a gentle electrical current to make canal measurements. Measuring the root canal is the only way to ensure the tooth is clean from tip to top. These measurements will also be used to determine the amount of filling needed to replace the pulp, but let's not get ahead of ourselves -- that comes next.

After taking measurements, the dentist will use a series of small files, endodontic files, each progressively larger in diameter, to clean and shape the inside of the tooth until all unhealthy tissue has been removed and the canal has been enlarged in preparation for the next step of the process, filling.

Filling Root Canals

When the inside of the pulp chamber and root canal are clean and hollow, it's time to fill and seal the tooth. Depending on the type of tooth being repaired, there may be one or multiple canals to treat. For example, molars have three to four root canals but top and bottom front teeth have just one or two.

This step of the root canal procedure may take place during the same appointment as the measuring and cleaning of the tooth, or, if the tooth or surrounding tissue was infected before the root canal procedure, the dentist may choose to treat and clear the infection before permanently filling and sealing the tooth.

When infection is present, the patient may be prescribed antibiotics, and the tooth may be temporarily filled with an antibiotic solution and sealed with a temporary filling to protect it as it heals. When the infection is resolved, the temporary filling is removed and the pulp chamber and root canal are filled and sealed just as if no infection had ever been there.

The pulp chamber and root canal are filled with a substance called gutta-percha. Gutta-percha is a rubbery latex material that, when heated and cooled to room temperature, becomes a hard but flexible plastic. Over the years, gutta-percha has been used not only in dental treatments, but also as an ingredient in gum, golf balls and as insulation for underwater cables. In root canal procedures, the material is used to keep the inside of the tooth free from bacteria and to give the tooth a strong core. The amount of gutta-percha needed is determined using those diagnostic x-rays as well as x-rays taken throughout the procedure. If additional core support is needed to ensure a healthy and stable tooth, a metal or plastic rod may also be inserted inside the canal.

When completely filled, the access hole drilled earlier is filled with a sealant paste. It's time to crown the tooth, the final step in the root canal procedure.

Root Canal Crowns

A temporary filling is just that -- temporary. To restore the tooth in a way in which it will last a lifetime without cracking or breaking, it will need a permanent crown -- a cap fitted and placed over the crown of the tooth. Permanent crowns are typically made in dental laboratories, and can be made out of a porcelain and metal compound, all metal, or all ceramic materials. The porcelain-metal compound and all-ceramic crowns look just like natural teeth.

When the affected tooth has been satisfactorily cleaned and filled, the crown is then cemented into place over the entire visible part of the repaired tooth, and then the procedure is complete.

Because the nerve was removed during the root canal, the repaired tooth may feel, well, not quite right. That's OK; this is a temporary adjustment. The tooth will behave just like a natural tooth, but it will no longer be sensitive to hot or cold temperatures -- it's the nerve that provided that sensation. Many patients report relief from any post-procedure pain and swelling with over-the-counter anti-inflammatory pain relievers, such as ibuprofen or naproxen. And most dentists schedule a post-treatment appointment to make sure the area has properly healed and that any infection has cleared.

Good oral hygiene at home and routine twice-yearly visits to a dentist are big steps toward preventing tooth decay and periodontal disease, two common oral health problems, and sticking with the combo long-term will increase your odds of keeping your natural teeth throughout your lifetime.

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Sources

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