Root canal treatment

11 min read

What is a root canal?

Root canal treatment is a dental procedure to treat infection at the centre of a tooth (the root canal system). Root canal treatment is also called endodontics.

The infection is caused by bacteria that live in the mouth and invade the tooth when:

  • tooth decay
  • fillings leak
  • teeth are damaged by trauma, such as a fall

Tooth structure

A tooth is made up of two parts:

  • The crown is the part of the tooth that is visible in the mouth.
  • The root extends into the bone of the jaw, anchoring the tooth in position.

These are composed of the following structures:

  • Enamel is the hard outer coating of a tooth.
  • Dentine is a softer material that supports the enamel and forms most of the tooth.
  • Cementum is a hard material that coats the root surface.
  • Dental pulp is the soft tissue at the centre of the tooth.

The root canal system contains the dental pulp and extends from the crown of the tooth to the end of the root. A single tooth can have more than one root canal.


The pulp is made up of soft tissue that includes nerves and blood vessels. If bacteria infect the pulp, it will begin to die. After this, the bacteria can increase in number. The bacteria and the substances they release will eventually pass out of the end of the root canal through the small hole where the blood vessels and nerves enter.

This process continues as there is nothing to stop more bacteria passing down the root canal, which causes the tissues around the end of the tooth to become red and swollen. This can cause your tooth to become painful and, in extreme circumstances, your face may become swollen (

dental abscess

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when root canal treatment should be done

The procedure

To treat the infection in the root canal, the bacteria need to be removed. This can be done by:

  • removing the tooth (extraction)
  • attempting to save the tooth by removing the bacteria from the root canal system (root canal treatment)

In root canal treatment, once the bacteria are removed, the root canal is filled and the tooth is sealed with a filling or crown. In most cases, the inflamed tissue at the end of the tooth will heal naturally.

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how root canal treatment is performed

Root canal treatment should not be painful because a

local anaesthetic
is normally given, it should be no more unpleasant than having a filling. The procedure is usually successful. In about 9 out of 10 cases, a tooth can survive for up to 10 years after root canal treatment.


It is important to look after your teeth when

recovering from root canal treatment
. You should also avoid biting on hard foods until all treatment is complete.

Most people can help prevent the need for further root canal treatment by:

  • maintaining good oral hygiene
  • being careful to avoid too much sugary food in your diet
  • quitting smoking, if you smoke

How it root canal treatment performed?

Root canal treatment is carried out by your dentist over two or more appointments. Unless you are entitled to free NHS dental treatment, you will have to pay for root canal treatment.

Find out about costs before you start treatment.

Your dentist may refer you to a specialist in root canal treatment (endodontist) if the work is particularly complex.


Before you have root canal treatment, your dentist may take a series of

of the affected tooth. This will allow them to build up a clear picture of the root canal and assess the extent of any damage.


Root canal treatment is usually carried out under

local anaesthetic
(painkilling medication). In some cases, where the tooth has died and is no longer sensitive, it may not be necessary to use a local anaesthetic.

Occasionally, teeth may be difficult to anaesthetise. In this case your dentist can use special local anaesthetic techniques to ensure your treatment is not painful.

Removing the pulp

Your dentist will first place a sheet of rubber (a rubber dam) around the tooth to ensure the tooth is dry during treatment. This also protects you from swallowing or breathing in any chemicals the dentist uses.

Your dentist will open your tooth through the crown, the flat part at the top, to access the soft tissue at the centre of the tooth (pulp). They will then remove any infected pulp that remains.

If you have a

dental abscess
(a pus-filled swelling), your dentist will be able to drain it at the same time.

Cleaning and filling the root canal

After your dentist has removed the pulp, they will clean and enlarge the root canal so it can be easily filled. The root canal is usually very narrow, which makes it difficult to fill.

Your dentist will use a series of small files to enlarge the canals and make them a regular shape so they can be filled. This part of the treatment may take several hours to complete and may need to be carried out over a number of visits.

Your front incisor and canine teeth (biting teeth) usually have a single root containing one root canal. The premolars and back molar teeth (chewing teeth) have two or three roots, each of which contains either one or two root canals. The more roots a tooth has, the longer the treatment will take to complete.

If the treatment is carried out over several visits, your dentist may put a small amount of medication in the cleaned canal in between visits to kill any remaining bacteria. The tooth will then be sealed using a temporary filling. If the infection has caused symptoms, such as a raised body temperature or a large swelling, you may be given antibiotics to help manage and prevent further infection.

Sealing and fixing the tooth

At your next visit, the temporary filling and medication within the tooth will be removed and the root canal filling will be inserted. This, along with a well-fitting filling, will seal the tooth and prevent re-infection.

Root-filled teeth are more likely to break than healthy unrestored teeth, so your dentist may suggest placing a crown (see below) on the tooth to protect it.

In some cases, a root-filled tooth may darken, particularly if it has died as a result of an injury, such as a knock to the tooth. There are several ways your dentist can treat discolouration, such as whitening the tooth using chemicals.


A crown is a cap that completely covers a real tooth. A crown might be necessary after root canal treatment to prevent the tooth from fracturing.

Crowns can be made from:

  • metal or porcelain (or both)
  • a ceramic material
  • powdered glass

Your tooth needs to be reduced in size and the crown is then used to replace what is removed. Your crown is made using a mould of your teeth to make sure that it is the right shape and size and that it fits your tooth accurately.

When fitting the crown, cement is used to glue the crown to the trimmed-down tooth. If there is only a small amount of tooth left after the root canal treatment, a post can be cemented in the root canal and used to help keep the crown in place.


Root canal treatment is usually successful at saving the tooth and clearing the infection.

One review of a number of studies found that 90% of root-treated teeth survived for 8 to10 years. The study also found that having a crown fitted to the tooth after root canal treatment was the most important factor for improving tooth survival rates.

If you practise good oral hygiene you should be able to successfully keep the tooth for a long time. The survival of your tooth depends on a number of factors including:

  • how much of the natural tooth remains
  • how well you keep your teeth clean
  • the biting forces on the tooth

However, if an infection does return, the treatment can be repeated. Alternatively, if treatment has already been carried out to a high standard and the infection remains, a small operation to remove the root tip (known as an apicectomy) may be carried out to treat the infection.

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recovering from root canal treatment

Recovery from root canal treatment

While you are having root canal treatment, avoid chewing or biting down on hard foods until the treatment has been completed. In some cases, this could be after several visits to the dentist.

After your final treatment, your restored tooth should not be painful, although it may feel sensitive for a few days. Over-the-counter painkillers, such as

, can be taken to relieve any discomfort. Always read the packet to make sure that:

  • the medication is suitable for you
  • you are taking the correct dose

Return to your dentist if you continue to experience pain or swelling after using painkillers.


After root canal treatment, clean the tooth in the same way as your other teeth and return to your dentist for check-ups as often as they advise.

Following the advice below will help ensure your teeth remain clean and healthy.

  • Brush your teeth twice a day, in the morning and in the evening.
  • Spend at least two minutes brushing your teeth each time.
  • Always use
  • Use a small toothbrush so you can reach your back teeth, and use no more than a pea-sized amount of toothpaste.
  • Flossing can be an effective way of cleaning the gaps between your teeth.
  • Do not brush too hard because this can damage your gums.

Read more information about [dental health].

When it should be done

Root canal treatment is only required when it is clear that the soft tissue at the centre of the tooth, called the pulp, has been damaged by a bacterial infection.

Your dentist can test your teeth and use

to establish whether a bacterial infection has occurred. Dental X-rays use radiation to take images of your teeth to identify any problems.

Symptoms of a pulp infection

Pulp infection is usually caused by

tooth decay

The symptoms of a pulp infection include:

  • pain when eating or drinking hot or cold food and drink
  • pain when biting or chewing
  • the tooth may become loose

As the infection progresses, these symptoms often disappear as the pulp dies. Your tooth then appears to have healed, but in fact the infection is spreading through the root canal system. Eventually further symptoms occur, such as:

  • pain when biting or chewing
  • swelling of the gum near the affected tooth
  • pus oozing from the affected tooth
  • facial swelling
  • the tooth becoming darker in colour

It is important that you see your dentist if you develop


Is there an alternative to root canal treatment?

If you have an infected tooth, the infected pulp cannot heal by itself. Leaving the infected tooth in your mouth may make it worse. There may also be less chance of the root canal treatment working if the infection within your tooth becomes established.

If you need root canal treatment, the only alternative is to have the tooth removed. However, this is not usually recommended because it is better to keep as many of your natural teeth as possible.

(medication to treat bacterial infections) are not effective in treating root canal infections. This is because the active ingredient in antibiotics can only work by reaching the site of the infection through your blood, and the bacteria that cause the infection are within the root canal system.

Repeated courses of antibiotics may also lead to bacteria adapting and finding ways to survive the effects of an antibiotic. They become antibiotic resistant, which means that the antibiotic no longer works.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.