Root Canal Treatment

Root Canal Treatment

Also called: Endodontic Treatment, Endodontic Therapy, Endodontic Microsurgery, Root Canal Therapy

Reviewed By:
Andrew M. Sicklick, D.D.S.


Root canal treatments are procedures designed to save teeth damaged by injury and/or severe tooth decay (cavities). The procedure may also be called root canal therapy or endodontic treatment. “Endo” means inside and “odont” means tooth in Greek. The procedure involves the removal of pulp, the soft tissue inside the tooth.

One or more root canals are found inside every tooth. Each canal contains pulp, often referred to as the nerve center of the tooth. Pulp actually consists of nerves, blood vessels and connective tissue. When that pulp is damaged by deep cavities or a fractured or cracked tooth, it can cause severe pain (toothache) and a root canal treatment may be needed.

There are multiple steps in a root canal treatment, but the basic procedure involves drilling into the top or back of the tooth, removing all or part of the pulp (pulpectomy), replacing it with a rubber-like material (such as gutta percha) and putting an artificial crown (cap) over the tooth to strengthen it. Patients may be given either a local or general anesthetic.

Root canal treatment may be performed on only one root or in more than one root in the same tooth. Depending on their type and location in the mouth, teeth can have up to four root canals per tooth.

The root canal procedure is typically performed in two or more dental appointments (each lasting 30 to 90 minutes, depending on the case). A dentist or an endodontist (a dentist trained in diagnosing and treating internal tooth disorders) can perform the procedure.

Certain alternatives to root canal treatment (e.g., pulp capping and pulpotomy) are typically used only on injured teeth. Pulling the tooth (tooth extraction) is an alternative, but dentists usually try to avoid this option. Extraction creates additional problems associated with missing teeth, including shifting or misaligned teeth, bite problems (malocclusion) and gum recession. In addition, missing teeth can dramatically alter a person’s appearance, which may be distressing.

Some people who undergo root canal treatment may need a second treatment if infection recurs in the tooth or if an infected root canal was overlooked during the initial procedure. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate.

The American Association of Endodontists (AAE) estimates that nearly 16 million root canals are performed each year in the United States. According to the American Dental Association, smokers are more likely than non-smokers to need root canal treatment.

Over the years, root canal treatments have gained a reputation for being painful. However, according to the AAE, root canal treatment today is no more painful than having a filling placed or another type of dental restoration.

About root canal treatment

A root canal treatment removes the tooth’s pulp (soft tissue at the center of the tooth that is composed of connective tissue, nerves and blood and lymph vessels). Also called root canal therapy and endodontic treatment, the procedure may be recommended to save a tooth when the pulp is infected or injured. The procedure may be performed by a dentist or endodontist (dentists who specialize in diagnosing and treating problems inside the tooth).

Infection due to tooth decay is the most common reason for root canal treatments. Tooth injury, such as a chipped, fractured or broken tooth, may also require root canal treatment. Teeth that are sensitive to hot and cold (sensitive teeth) may need root canal treatment if other desensitizing methods fail. In addition, repeated dental procedures (e.g., artificial crowns or fillings) on the same tooth can weaken the tooth and prompt a root canal treatment.

Pulp begins at the tip of the root, where the tooth is anchored into the jaw, and travels through the root canals, which are long, thin passageways that lead up to the pulp chamber at the center of the tooth. The chamber is an area inside the crown and below the enamel and dentin. A tooth has only one pulp chamber but may have up to four root canals leading to the chamber. Therefore, root canal treatment on a single tooth may involve removing pulp from multiple root canals that are infected or damaged.

The pulp’s primary function is to supply nourishment (blood and nutrients) for growing teeth while the nerve within the pulp sends messages to the brain, such as whether a drink or food is hot or cold. The nerve also sends pain messages when there is an injury or infection.

Removing an infected pulp does not harm the tooth but does eliminate pain caused by infection or injury by removing the central nerve tissue of the tooth.

In children’s permanent teeth, which are continuing to grow, a procedure called a pulpotomy may be attempted In this procedure, only part of the dead or infected pulp is removed, so the blood vessels can continue to nourish the tooth.

For many people, root canal treatment is preceded by severe pain (toothache). The source of that pain is typically an abscess (a pocket of pus) that can form at the tip of the root when the pulp is infected.

A root canal may be necessary even if there is no pain, when x-rays or a dental examination reveal root cavities or darkened teeth (an indication of dead of dying pulp).

Root canal therapy can be used to treat both primary teeth (baby teeth) in children or permanent (adult) teeth. However, depending on the kind of injury involved with a child’s baby teeth, extraction may also be an option. When extracting baby teeth, it is important to discuss the need for space maintainers. These orthodontic appliances maintain the space of the baby tooth, so that the replacement adult tooth will be able to erupt into the mouth.Dentists try to avoid extracting teeth because doing so can create other mouth problems.

Some people who undergo root canal treatment may require repeated treatments if the initial procedure fails to completely rid the tooth and canal of bacteria and reinfection occurs. Others may require an additional procedure called an apicoectomy if infection spreads to the tip of the tooth’s root (apex). This procedure is also called endodontic microsurgery because it uses a microscope to guide the endodontist in cutting out the infected root tip.

Root canal treatment has long had a reputation as being very painful, and many patients may have chosen to forego the procedure – opting to have the problem tooth pulled instead. However, according to the American Association of Endodontists (AAE), dental techniques and anesthesia have improved in recent years and the painful root canal is largely a myth today. Patients often report the pain to be no more severe than that of a filling, according to the AAE. In many cases, the anticipation of a root canal treatment is worse than the treatment itself.

According to the AAE, nearly 16 million root canals are performed each year in the United States. Estimates are that half of U.S. adults have had root canal treatments by age 50, according to the American Dental Association (ADA). Smokers are 70 percent more likely than non-smokers to need root canal treatments, according to the ADA.

Conditions treated using root canal treatment

Root canal treatment is generally recommended when there is infection or injury to the tooth’s pulp – the soft tissue (nerve endings, blood vessels and connective tissue) at the center of every tooth.

Specific conditions that may require root canal treatment include the following:

  • Deep cavity. Untreated dental caries caused by rampant tooth decay. When plaque builds up on teeth, bacteria can eat into the enamel (the hard outer layer) and continue to the dentin layer below. That dentin surrounds the pulp. When decay reaches the pulp, it can cause irreversible pulpitis, a prolonged inflammation with internal tooth pressure leading to decreased blood flow to the pulp. Eventually, the pulp tissue dies (necrosis) and further infection (an abscess) can form in the gums or tooth roots. An abscess is a painful pocket of pus that may emit tissue-destroying toxins. If left untreated, the abscess can lead to erosion of the connective tissues and bones anchoring teeth to the jaw (periodontium).
  • Unsuccessful previous root canal treatment. If infected tooth or pulp tissue was not completely removed during an initial root canal procedure, there is a chance of reinfection and renewed pain. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate. Other factors that might prompt a second procedure are when a canal is fractured by a dental instrument during the initial treatment or when a branch of a root canal goes unnoticed during the first procedure.

  • Weakened teeth. Repeated fillings, broken crowns or root fractures (caused as a result of or following dental procedures) may cause a tooth to lose so much of its structure that a root canal is necessary to strengthen the tooth. The dentist or endodontist can put a metal or plastic post into the root and recap the crown to help save the tooth.

  • Acute dental trauma. This may include sports injuries, auto accidents or other trauma to the face or mouth. The types of tooth injuries include:

    • Crown fracture. When the pulp is exposed due to a chipped, cracked or broken tooth crown.

    • Crown/root fracture. When the enamel and dentin in the crown as well as the cementum covering the root are cracked or damaged. This can occur with or without exposure of the pulp.

  • Sensitive teeth. If other attempts to desensitize teeth (e.g., special toothpastes, resins and gels) fail to work, the dentist may recommend a root canal treatment to remove the tooth’s nerve center. Sensitivity to hot and cold sensations on the tooth or on roots exposed by gum recession can cause pain and discomfort. Pain when consuming hot foods and drinks can indicate the nerve is dying.

Root canal treatment may be necessary if severe pain results from biting, touching or pushing a tooth. Swelling near the tooth may also indicate the need for treatment.

Before the root canal treatment

The dentist can perform the root canal treatment or refer patients to a specialist trained in diagnosing and treating internal tooth disorders (an endodontist). The root canal treatment typically requires two or more dental appointments, although more may be necessary for more complex cases (e.g., abscesses and severe infection).

Prior to starting treatment, the patient may want to discuss the pros and cons and alternatives to root canal treatment. Also, patients should learn the specifics of their treatment plan for their particular condition. The number of visits it will require and the length of each visit for root canal treatment often vary. The time for each visit also varies, generally from 30 to 90 minutes. Knowing what to expect can help patients avoid anxiety prior to and during these visits. Such anxiety can cause stress that may be worse than the root canal treatment, itself.

The dentist or endodontist will usually discuss the type of sedative or anesthesia that can be used (e.g., local, general). Some weak anesthetics, such as nitrous oxide, can help relieve anxiety. For those undergoing general anesthesia, a physical examination may be recommended prior to treatment to determine if the patient has any conditions that may interfere with the anesthesia.

A dentist may need to remove a patient’s artificial crown or other dental appliances (e.g., a fixed bridge on abutment teeth) before root canal treatment can be performed. This typically requires a separate appointment to prepare the tooth for the actual root canal procedure.

An abscess on the roots or gums may delay the root canal procedure for a week or more while the pus is drained. The pus in an abscess releases a toxin that can make anesthesia less effective during the root canal procedure. The dentist may prescribe antibiotics and wait until the infection clears up before starting the root canal treatment.

Some people may require a dose of antibiotics taken prophylactically (before the procedure) to reduce the risk of bacteria in the teeth causing complications elsewhere in the body. In such cases, the medications are usually taken one hour before each appointment. People may need this precaution if they have:

  • Certain heart disorders
  • Rheumatoid arthritis
  • Compromised immune systems
  • Undergone certain procedures (e.g., heart valve repair, joint replacement)

Patients are urged to inform the dentist or endodontist of any medications, vitamins or herbal supplements they are taking prior to the procedure. These substances can interact with the anesthetic, possibly making it less effective at numbing pain. Some medications (e.g., certain osteoporosis or cancer medication) may also require the dentist or endodontist to use different techniques to help prevent complications. Patients should also inform the dental staff about any pre-existing medical conditions (e.g., diabetes, HIV), which may affect the stages of healing.

Some experts recommend selecting a time for dental procedures when the patient will be the most relaxed (early morning or weekends) and to avoid making plans and appointments for immediately after the root canal treatment. Patients may need to make arrangements for someone to drive them home following the procedure, especially if general anesthesia is used.

Finally, patients are urged to strictly follow the preparatory instructions of the dentist or endodontist prior to the procedure. This may include a checklist to follow the night before or morning of the appointment. Depending on the kind of anesthetic being used, there may be restrictions on food and water prior to the procedure. If there are no food or diet restrictions, patients may want to discuss the appropriateness of eating a meal prior to the procedure since it may be too painful or uncomfortable to chew for several hours following the appointment.

During the pulpectomy

Root canal treatment actually involves a series of visits to prepare the tooth, remove the tooth’s pulp (pulpectomy) and then finish the restoration, which usually involves the placement of an artificial crown. For minor cases of pulp damage, the entire process may be completed in one appointment. If there are no complications (such as severe infection or an existing artificial crown), the pulpectomy is performed during the first dental appointment.

Of this series of appointments, it is the pulpectomy itself that is often referred to as the root canal treatment. The pulpectomy may involve the following steps:

  • X-rays can be taken immediately before the root canal procedure to show the location of root canals (there may be multiple canals), whether tissue infection exists in and around the tooth and if nerve endings are nearby.

  • A local anesthetic may be administered to numb the nerves in and around the tooth. Nitrous oxide gas may also be used on some patients to help reduce anxiety. Those who have difficulty sitting still during a dental procedure – children, those with severe anxiety or mental illness or physical disabilities – may need a general anesthetic.

  • A rubber sheet called a dental dam is placed over the affected tooth to keep it isolated and free of saliva and to keep debris from falling down the throat. A suction tube is placed into the mouth to dry up excess saliva.

  • A hole is drilled into the tooth to reveal the pulp chamber. In molars and bicuspids, the hole is usually drilled through the top (crown) of the tooth. In incisors, the hole is usually drilled through the interior side of front teeth.

  • The pulp is removed. Chemicals (e.g., sodium hypochlorite, hydrogen peroxide) and dental instruments (e.g., root canal files and reamers) are used to clean dead and infected tissue from the inner tooth. The root canals are enlarged and shaped using a series of thin files that increase in width as the canal is opened. Medication (antibiotics) may be placed into the site to eliminate bacteria.

  • A temporary filling is usually placed into the crown to protect the drilled area from infection and saliva. In some cases, the dentist may leave the tooth open to drain for a few days.

Patients who feel pain or discomfort during the procedure are urged to notify the physician immediately. This may be an indication that the anesthetic is wearing off. The dentist or endodontist may recommend a signal (such as holding up a finger or hand) to indicate when there is pain.

After the pulpectomy

Immediately following the pulpectomy, there may be numbness in the lips, mouth, tongue or jaw for one or two hours after the procedure. This is normal. The patient may want to avoid chewing during this time. As the anesthetic wears off, there may be a tingling sensation in the mouth and jaw. Antibiotics may be prescribed if there is evidence of infection extending beyond the root.

The dentist may advise the patient to avoid chewing or biting with the treated tooth since the temporary filling is not as strong as the permanent filling. Sometimes a thin layer of the temporary filling can wear off. If the entire filling dislodges or comes out, the patient is urged to call the dentist or endodontist.

There can be discomfort (pain, soreness or inflammation) for a few days after the procedure. The dentist may recommend over-the-counter pain relievers and/or anti-inflammatory agents or prescribe stronger analgesics (pain medications).

Patients should follow the post-operative care instructions provided by the dentist, including directions for brushing and flossing the affected tooth or special mouth rinses. If pain or inflammation continues or worsens beyond a few days, it could be a sign of infection or other complication. If this happens, the patient is urged to call the dentist or endodontist.

The patient may be asked to wait a week or more to allow the tissues to heal from the pulpectomy and then return for the permanent filling and restoration. These may be completed in one or multiple visits. While an endodontist that performed the root canal treatment may also fill and seal the tooth, patients typically return to a general dentist for restoration of the crown – the portion of the tooth visible above the gum line.

Anesthesia options for all restoration visits, the use of prophylactic antibiotics and other factors are usually addressed as part of the overall root canal treatment plan determined prior to the pulpectomy (see Before the treatment). However, questions or concerns can be readdressed prior to each stage of the restoration.

First, the temporary filing is removed and the pulp chamber and root canal are filled with a permanent material (gutta percha). Adhesive and cement are also placed into the canal to help seal it. A metal or plastic post may be placed into the canal to support the tooth, which may have little of its original structure. In most cases, the tooth will require an artificial crown, especially for teeth used for chewing, such as the molars.

The dentist may recommend patients avoid chewing or biting on the tooth until the final crown has been completed. This will reduce the risk of infection, cracking or fracturing the tooth. Even after the crown is restored, it may be necessary to avoid chewing hard foods (e.g., nuts or hard candy) with the tooth to lessen the chance of damaging the artificial crown.

There may be follow-up exams with the dentist or endodontist to check progress of healing. The patient may be advised to follow good oral hygiene (brushing and flossing daily) and get twice yearly dental checkups.

Potential benefits of root canal treatment

The ultimate goal of root canal treatment is saving the injured or infected tooth. Teeth restored with root canal treatment can last the rest of the patient’s life. The benefits of having the procedure include:

  • Relieving pain (toothache) associated with pulp infection, sensitivity or damage.

  • Ridding the tooth of decayed tissue that can spread to other teeth.

  • Restoring a natural smile to those whose teeth have been cracked or chipped.

  • Avoiding extraction. Pulling a tooth can relieve the pain associated with a toothache and infection. However, it can also open the door for other problems. They may include shifting and misaligned teeth, gum recession, bite problems (malocclusion) and social problems associated with missing teeth.

Potential risks with root canal treatment

Like all medical procedures, there can be risks associated with root canal treatment. Patients are urged to discuss the entire procedure as well as any risks or complications before, during and after each step of the treatment.

Some people report experiencing pain during the root canal treatment. This can happen when the anesthesia fails to completely numb the nerves in and around the infected tooth. Anesthesia may also be affected by toxins released from an abscess (a pocket of pus that can form on the gums or at the roots when there is severe infection). When that pus oozes onto the gums, it can make anesthesia less effective at numbing the nerves. However, dentists are often aware of the presence of an abscess prior to the procedure and can take steps to minimize its effects on the anesthesia.

Another possible risk is that the procedure will not relieve pain or fix the problem that caused the pain. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate. When the initial root canal therapy fails, a second treatment may be necessary. This means months or sometimes years later the entire procedure is redone, including placement of the artificial crown. Possible causes of treatment failure include:

  • The original treatment failed to remove all of the infected pulp tissue and decayed tooth fragments and re-infection occurs.

  • The tooth contained an additional root canal that was missed during the initial treatment, such as a narrow, curved branch of the main root canal.

  • The infection spread to the tip of the tooth’s root (apex) or into the alveolar bone. Another procedure called an apicoectomy may be needed to remove the root tip.

  • The adhesive or cement used to seal the root canal begins to leak.

  • The weakened tooth cracks or fractures.

There are also risks associated with use of anesthesia. The injection needle used to administer local anesthetics can hit a nerve and cause extended numbness and pain. General anesthesia can cause nausea and vomiting that typically wears off within 24 hours.

Alternatives and variations

Depending on the severity and type of injury or infection in the tooth, there may be alternatives to root canal treatment. These options may include:

  • Tooth extraction. Pulling the tooth. In certain facial and dental trauma cases, it may be impossible to save the tooth. Patients may insist on pulling the tooth because they fear root canal procedures or cannot afford to pay for the procedure. In general, pulling the tooth is avoided whenever possible because it opens the door for other problems such as misaligned or shifting teeth, gum recession and bite obstructions (malocclusion). The patient will need bridges, partial dentures or implants to replace the extracted tooth.

  • Pulp capping. Placing a medicated dressing over exposed pulp. This is performed when a child’s primary teeth (baby teeth) are cracked or fractured leaving the pulp exposed. This saves the baby tooth so the permanent tooth can grow in normally. Pulp capping can also be used on adult teeth that have fractured crowns or crown/root fractures.

  • Pulpotomy. Removing the part of the pulp that is dead (necrotic) and leaving the vital portions in the canal. This is typically performed on primary or permanent teeth where cracked or fractured teeth or roots cause death of some of the pulp tissue.

There is risk of failure in both pulp capping and pulpotomies because the procedures may not prevent further pulp necrosis. In that case, a root canal treatment would still have to be performed.

A variation of the root canal treatment involves gum surgery that is performed after a root canal has failed and infection recurs in the root’s tip (apex). When that happens, the endodontist performs an apicoectomy (endodontic microsurgery). This is also called a root end resection or root resection. An incision is made in the gums to open a flap near the infected root tip. The infected tissue is removed along with the root tip. A sealant is used to close the tip and the patient’s gums are sutured back together.

Questions for your doctor

Preparing questions in advance can help patients to have more meaningful discussions with their dentists regarding their conditions. Patients may wish to ask their doctor the following questions regarding root canal treatment:

  1. Why are you recommending I have a root canal treatment?
  2. Am I a candidate for an alternative treatment? What are the pros and cons of each?
  3. What are my options for relieving anxiety during the procedure?
  4. What are my pain relief options during the procedure?
  5. Do I have any conditions that would require me to take antiobiotics prior to the procedure to reduce the risk of infection?
  6. How do I let you know if I feel pain during the actual procedure?
  7. Can I do the entire root canal treatment in one appointment?
  8. What are the chances I will need another root canal treatment at some point?
  9. What are the pros and cons of having the tooth pulled instead?
  10. Why can’t my regular dentist do the root canal? Why do I have to see an endodontist?
  11. Why do I need a second root canal on the same tooth?
  12. How much pain or discomfort should I expect after the procedure?
  13. Will I be able to eat anything I want following the procedure or will I have to avoid certain foods?
  14. What signs or symptoms after the procedure should I immediately report to a dentist?
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