Root canal treatment


Root canal treatment


Root canal treatment is a dental procedure used to treat infection at the centre of a tooth (the root canal system). It's also known as 'endodontics'.

The infection is caused by bacteria that live in the mouth and invade the tooth. This can happen after:

tooth decay

leaky fillings 

damage to teeth as a result of trauma, such as a fall

Tooth structure

A tooth is made up of two parts. The crown is the part of the tooth that's visible in the mouth. The root extends into the bone of the jaw, anchoring the tooth in position.

Teeth also consist of:

enamel – the hard outer coating

dentine – a softer material that supports the enamel and forms most of the tooth 

cementum – a hard material that coats the root's surface

dental pulp – 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. The pulp will begin to die if it's infected by bacteria. Bacteria can then multiply and spread.

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 will continue because there's 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 make your tooth painful and, in extreme cases, your face may become swollen (known as a dental abscess).


The procedure

To treat the infection in the root canal, the bacteria need to be removed.

This can be done by either removing the tooth (extraction) or attempting to save it by removing the bacteria from the root canal system (root canal treatment).

After the bacteria have been removed, the root canal will be filled and the tooth sealed with a filling or crown. In most cases, the inflamed tissue at the end of the tooth will heal naturally.

Before having root canal treatment, you will usually be given a local anaesthetic. This means the procedure shouldn't be painful, and should be no more unpleasant than having a filling.

Root canal treatment is usually successful. In about 9 out of 10 cases, a tooth can survive for up to 10 years after root canal treatment.



It's important to look after your teeth when recovering from root canal treatment.

Avoid biting on hard foods until all of your treatment is complete.

In most cases, it's possible to prevent the need for further root canal treatment by:

maintaining good oral hygiene

not consuming too much sugary food

giving up smoking (if you smoke)


When root canal treatment should be carried out 

Root canal treatment is only required when it's 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 X-rays to establish whether there's a bacterial infection. Dental X-rays use radiation to take images of your teeth and can be used to identify any problems.

Pulp infection

A 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

a loose tooth

As the infection progresses, these symptoms often disappear as the pulp dies. Your tooth then appears to have healed, but the infection has in fact spread through the root canal system. Further symptoms eventually 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 a darker colour

It's important to see your dentist if you develop toothache.

Tooth removal

If your tooth is infected, the pulp can't 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 isn't usually recommended, because it's better to keep as many of your natural teeth as possible.

Antibiotics (medication to treat bacterial infections) aren't 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 medication's effects. They become resistant to antibiotics, which means that the antibiotic no longer works.


How root canal treatment is performed 

Root canal treatment is carried out by your dentist over two or more appointments.

Unless you're entitled to free dental treatment, you will have to pay for root canal treatment.

You should find out about costs before you start treatment. 

If the work is particularly complex, your dentist may refer you to a specialist in root canal treatment, known as an endodontist.

All registered dental specialists in the UK are listed on the website of the General Dental Council (GDC). You can search the register for a specialist.


Before having root canal treatment, your dentist may take a series of X-rays 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 that numbs a specific area of the body). 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. On these occasions, your dentist can use special local anaesthetic techniques to ensure your treatment isn't painful.

Removing the pulp

Your dentist will place a rubber sheet (dam) around the tooth to ensure it is dry during treatment. The dam will also prevent you 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 the pulp has been removed, your dentist 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 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 containing either one or two root canals. The more roots a tooth has, the longer the treatment will take to complete.

If the treatment needs to be carried out over several sessions, 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 you have symptoms from the infection, such as a raised temperature or 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 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 due to 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. It might be necessary to use a crown after root canal treatment to prevent the tooth fracturing.

Crowns can be made from:

metal or porcelain (or both)

a ceramic material

powdered glass

The size of your tooth will be reduced and the crown will be used to replace what's removed. A mould of your tooth will be taken to ensure the crown is the right shape and size, and fits your tooth accurately.

When fitting the crown, cement will be used to glue the crown to the trimmed-down tooth. If there's 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 8-10 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, your treated tooth should survive 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

If an infection does return, however, 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 (an apicoectomy) may be carried out to treat the infection.


Rate your dentist Recovering from root canal treatment 

While you're having root canal treatment, avoid chewing or biting down on hard foods until the treatment has been completed.

In some cases, this may be after several visits to the dentist.

After your final treatment, your restored tooth shouldn't be painful, although it may feel sensitive for a few days. Over-the-counter painkillers, such as paracetamol or ibuprofen, can be used to relieve any discomfort.

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 visit 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 evening.

Spend at least two minutes brushing your teeth each time.

Always use fluoride toothpaste.

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.

Don't brush too hard because it can damage your gums.