Root canal treatment (endodontic treatment) treats infection or damage inside a tooth so the tooth can be kept rather than removed. This article explains why it is needed, the warning signs, what happens during treatment, including urgent cases, recovery, risks, alternatives and common myths.

What root canal treatment is

Inside each tooth is the pulp, soft tissue containing nerves and blood vessels that runs from the crown down through narrow channels in the roots (the root canals). If the pulp becomes inflamed or infected, it cannot heal on its own. Treatment removes the damaged pulp, cleans and disinfects the canals, and seals them to stop bacteria getting back in.

Why the pulp becomes damaged

Deep decay that reaches the pulp, the most common cause.
Cracks or fractures that let bacteria in.
Injury, such as a knock in sport or a fall. The pulp can die months or years later even if the tooth looked undamaged at the time.
Repeated or very deep fillings that irritate the pulp over time.

Signs a tooth may need treatment

Severe or throbbing toothache, or pain that wakes you at night.
Pain when biting or chewing.
Sensitivity to hot or cold that lingers after the food or drink is gone.
Swollen or tender gums near the tooth, or a pimple-like bump on the gum that may leak pus.
A bad taste or bad breath from the area.
A tooth that has turned grey or darker.

Some infected teeth cause no pain at all and are found on X-rays at a check-up.

When it is urgent

Severe pain, swelling of the gum or face, or a tooth knocked hard in an accident should be seen promptly. If swelling spreads towards the eye or neck, or causes difficulty breathing or swallowing, or there is a high fever, seek urgent medical care. In an urgent visit the dentist may clean out the infected pulp and place a dressing to relieve pain, then complete treatment at later visits. Antibiotics alone do not fix an infected tooth, although they are sometimes used when infection is spreading.

What happens during treatment

Assessment. The tooth is examined and X-rays are taken to see the shape of the canals and any infection.
Anaesthetic. Local anaesthetic numbs the tooth and area. A thin rubber sheet (dental dam) is placed to keep the tooth dry and clean.
Access. A small opening is made through the top of the tooth to reach the pulp.
Cleaning and shaping. The pulp is removed and the canals are cleaned, shaped and disinfected with fine instruments and rinses.
Filling. The canals are filled and sealed, usually with a rubber-like material called gutta-percha.
Restoring the tooth. A temporary filling is placed, followed by a permanent filling or, often for back teeth, a crown to protect the tooth from cracking.

Treatment may take one to three appointments, depending on the tooth, the number of canals and how much infection is present.

Recovery and aftercare

The tooth and gum are often tender for a few days. Pain relief such as paracetamol or ibuprofen, if suitable for you, usually helps.
Avoid chewing hard food on the tooth until the final filling or crown is in place, as a treated tooth with a temporary filling can break.
Brush and floss as usual, gently around the tooth.
Contact the dentist if pain or swelling gets worse after a few days, the temporary filling comes out, or your bite feels high.

Benefits

Relieves the pain caused by an inflamed or infected pulp.
Keeps your natural tooth, avoiding the gap left by an extraction and the shifting of nearby teeth.
Restores normal biting and chewing once the tooth is properly restored.

A well-treated and well-restored tooth can last for many years with good care and regular check-ups.

Risks and complications

Persistent or returning infection if bacteria remain in hard-to-reach parts of the canals, or if new decay or a leaking filling lets bacteria back in. Re-treatment or minor surgery at the root tip may be possible.
Cracked tooth: treated teeth can be more brittle, which is why a crown is often advised.
Procedural problems such as a small instrument separating in a canal, or a perforation, which are uncommon.
Numbness from nerve irritation, which is rare.

Some teeth have curved, narrow or extra canals, and may be referred to an endodontist, a registered specialist in root canal treatment.

Alternatives

Extraction: removing the tooth ends the infection, but the gap may then need an implant, bridge or denture to prevent other teeth shifting.
Pulpotomy: removing only the top part of the pulp. This is mostly used for children’s baby teeth and occasionally for young adult teeth.
Leaving it untreated is not recommended, as infection can spread and the tooth will usually get worse.

Common myths

“Root canals are very painful.” With local anaesthetic, most people find treatment similar to having a filling. The treatment relieves the pain of the infection.
“It’s better to just pull the tooth.” Keeping a natural tooth is usually preferred when it can be saved and restored.
“Root canal treatment causes illness elsewhere in the body.” This idea comes from old research that has not been supported by modern studies.
“Only people with poor hygiene need one.” Injury, cracks and old fillings can damage the pulp in anyone.

Prevention

Brush twice a day with fluoride toothpaste and clean between your teeth daily.
Limit sugary food and drinks.
Wear a mouthguard for contact sports.
Have regular check-ups so decay and cracks can be treated early.