Root canal treatment - How it is performed 

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 NHS dental treatment, you will have to pay for root canal treatment.

You should find out about costs before you start treatment. Read our page on NHS dental services for more information about dentists and treatment costs.

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.

Read more about what NHS dental fillings and crowns are made of.


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.

Read more about recovering from root canal treatment.

Page last reviewed: 23/07/2014

Next review due: 23/07/2016


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The 5 comments posted are personal views. Any information they give has not been checked and may not be accurate.

User843210 said on 08 February 2014

I'm 15 and I have to go and have root canal on one of my teeth and 2 fillings in another and then another 1 filling in another, due to dental cavities. I am so shocked at this. I had to get an emergency appointment due to toothache caused by infection. Luckily, I saw a different dentist to my usual one as he didn't spot any of this and my teeth are too crowded, therefore, he has referred me to an orthodontist. At my emergency appointment the dentist told me that I needed fillings and root canal BEFORE the orthodontist will even see me. I feel so let down by my dentist. Because I dislike the dentist, I'm having it all done under sedation (luckily). I'm also on strong antibiotics because of it. I am just thinking I'm 15, I shouldn't need this done, my teeth should be in good condition, but they're too crowded. (I do brush my teeth 2-3 times a day with an electric toothbrush, and mouthwash) Feel let down by my old dentist.

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ses5684 said on 15 May 2012

I went for my first two fillings one was a spot filling and one was supposedly “not deep”. So the one that was “not deep” caused me problems and was replaced and was found after all to be very deep with a small crack in my tooth which is now causing me more problems than before, 10 times worse in fact. I was told if my tooth didn’t resolve that I would end up with a root canal (amalgam, dentist didn’t say whether or not it was going to have a crown but my guess is that it was going to be very unlikely from the way she said “your tooth won’t be white anymore”).
I sought advice from a well experienced dentist and he said quote “I’m skeptical of the skills of your dentist”. There is no way I am letting someone who has literally walked out of dentistry school loose on my tooth again, I would prefer it to be done by someone who has done it a million times over.
The dentists always say root canal is always down to poor dental hygiene, half true half false. I am 23, I’ve always looked after my teeth, always done what is recommended. I have to point out that sometimes it can be down to having a poor dentist, as my mum says it even jr doctors these days are literaly thrown into the job, dentist are not trained the way they used to. Sometimes you don’t have an infection or an abscess, sometimes it’s just the dentist going deeper and deeper, so much so it comes to the point of no return and your nerves die or begin to die. Or they use improper techniques
This is the worst for me, I never thought after 2 months of having one simple filling I would have to go through this and now I will have to class one of my teeth as “dead” and to come to terms with eventually losing it. I’m now £53 out of pocket and one root canal to go.

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RetiredDentist said on 29 April 2012

Unfortunately in 2006 the Government of the day decided to abandon the old system of paying dentists in England for each item of treatment they did, and replace it with a system where the dentist was paid the same for a course of treatment regardless of how many fillings or other treatment were needed. Root canal treatment is very expensive to carry out properly and cannot be done at the price allowed - the dentist could make a loss of hundreds of pounds. Your PCT is supposed to provide the treatment, but often cannot. in Scotland the dentists who work in the Scottish Health Service are still paid for each item of treatment they carry out.

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thegrinch said on 06 May 2011

This page fails to mention to mention that the results are very much dependent upon the operator, and doesn't mention things that patients should look out for, for example:

- that a rubber dam is used to isolate the tooth from contamination and protect the patient from inhaling or swallowing endodontic instruments

- that at the very least, magnifying loupes are used by the dentist

- that root treated molar teeth should be crowned.

Success rates are much lower when these principles are not adhered to. Although this is the standard of care, in practice it would appear that some dentists take short-cuts, especially when under time pressure. Patients need to be aware of this and either insist on appropriate treatment or seek out a specialist endodontist.

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mugrat said on 18 October 2010

This is a good description of the condition and the treatment I have received for a root canal infection. However, I feel the emphasis on dental hygiene implicitly "blames the victim" for a situation that commonly arises in middle age regardless of the individual's attention to dental hygiene. Some people, like me, seem to have a genetic susceptibility to these infections, and I know that things were bad for me whenever I was pregnant, so it's a bit simplistic, not to say demoralising, to have a painful condition ascribed to insanitary habits or laziness!

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