Root canal treatment (endodontics) is a dental procedure used to treat infection at the centre of the tooth.

Root canal treatment is not painful and can save a tooth that might otherwise have to be removed completely.

Why it's needed

The infection at the centre of the tooth (the root canal) 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 2 parts. The crown is the top part of the tooth that's visible in the mouth.

The root extends into the jaw bone, 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 1 root canal.

When root canal treatment is needed

Root canal treatment is required when dental  X-rays show that the pulp has been damaged by bacterial infection.

The pulp will begin to die if it's infected by bacteria, allowing the bacteria to them multiply and spread.

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.

You eventually get further symptoms such as:

• pain when biting or chewing returning
• swelling of the gum near the affected tooth
• pus oozing from the affected tooth
• a swollen cheek or jaw
• the tooth becoming darker in colour

It's important to see your dentist if you develop toothache. If your tooth is infected, the 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.

Antibiotics, a medicine to treat bacterial infections, are not effective in treating root canal infections. They can though help to treat infection that spreads beyond the root and causes swelling.

How root canal treatment is done

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

This can be done by either:

• removing the bacteria from the root canal system (root canal treatment)
• removing the tooth (extraction)

But removing the tooth is not usually recommended as it's better to keep as many of your natural teeth as possible.

Before having root canal treatment, you'll usually be given a local anaesthetic.

This means the procedure should be painless and no more unpleasant than having a filling.

After the bacteria have been removed, the root canal is filled and the tooth sealed with a filling or crown.

In most cases the inflamed tissue near the tooth will heal naturally.

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.

Recovering from root canal treatment

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

You should avoid biting on hard foods until your treatment is complete.

After your final treatment, your restored tooth should no longer be painful, although it may feel sore for a few days.

You can take over-the-counter painkillers, such as paracetamol or ibuprofen, to relieve any discomfort.

Return to your dentist if you still have pain or swelling after using painkillers.

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

• keeping your teeth clean 
• not eating too much sugary food
• giving up smoking if you smoke. You can get help and support for this by visiting https://www.helpmequit.wales/ or calling Freephone 0808 163 3129

Root canal treatment is carried out by your dentist over 2 or more appointments.

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

Read about:

• NHS dental charges
• Getting help with dental charges

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).

Preparation

Before having root canal treatment, your dentist may take a series of X-rays of the affected tooth.

This allows 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, a painkilling medication that numbs your infected tooth and the gum around it.

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

Removing the pulp

Your dentist will place a rubber sheet (dam) around the tooth to ensure it is dry during treatment.

The dam also prevents 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'll then remove any infected pulp that remains.

If you have a dental abscess, which is 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.

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 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 is removed and the root canal filling will be inserted.

This, along with a filling, seals the tooth and prevents reinfection.

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

In some cases a root-filled tooth may darken, particularly if it has died as a result of injury like a knock to the tooth.

There are several ways your dentist can treat discolouration, such as whitening the tooth using chemicals.

Adding a crown

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 dentist will use a drill to reduce the size of your tooth and use the crown 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.

How successful is root canal treatment?

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

Around 9 out of 10 root-treated teeth survive for 8 to 10 years.

Having a crown fitted to the tooth after root canal treatment is important for improving tooth survival rates.

If you keep your teeth clean, 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.

Or if treatment has already been carried out to a high standard and the infection remains, a small operation to remove the root tip (an apicectomy) may be carried out to treat the infection.