Root canal treatment explained

If your dentist has mentioned a root canal, you probably have two questions: will it hurt, and is it worth having? The treatment deals with a problem in the soft centre of the tooth, most often an infection, and it is usually carried out under local anaesthetic.

What is a root canal?

The pulp is the soft tissue at the centre of a tooth, where its nerve and blood supply sit. When bacteria reach it, the pulp can become infected. The NHS says the pulp can become infected because of tooth decay, gum disease, a chipped, broken or cracked tooth, or a dental abscess (a build-up of pus). A 2025 summary of the European Society of Endodontology guideline says these tooth diseases are mainly caused by bacteria.

Root canal treatment removes the infection from inside the tooth. The inside is then cleaned and filled to help stop it becoming infected again.

Why might you need one?

Root canal treatment may be recommended if you have tooth pain caused by an infected tooth, the NHS says. An infection that has formed an abscess can also bring sensitivity to hot or cold, a bad taste, and swelling of the face or jaw.

A tooth can be infected without hurting, though. The same guideline summary says an infection at the tip of the root may cause symptoms or may not, and generally shows up on an X-ray.

Without treatment, the NHS says an infected tooth may need to be taken out. Where a tooth can be restored, the guideline summary recommends root canal treatment, a suitable restoration and follow-up care in preference to extraction.

Does it hurt?

You will usually be given a local anaesthetic, so you are awake but do not feel pain, according to the NHS. The Oral Health Foundation says the treatment should feel similar to having a filling.

What happens during treatment?

Between them, the NHS and the Oral Health Foundation describe these steps:

1. Your dentist makes a small opening in the tooth.
2. The infected pulp is removed. If there is an abscess, it is drained.
3. The inside of the tooth is cleaned, shaped and disinfected.
4. The tooth is filled and sealed. Between visits it may have a temporary filling.

Both say you will usually need at least two appointments, and the NHS says they may last 1 to 2 hours, or sometimes longer. A leaflet from the British Endodontic Society says most cases can be completed in one or two visits. For an infection at the root tip, the European guideline strongly recommends a single visit where the dentist has completed all the steps properly. A 2022 Cochrane review of 47 studies, in people aged over 10, found no evidence that treating in one visit works better or worse than treating over several, although more people reported pain within a week of a single visit. Your dentist will tell you what your tooth needs.

What has changed over the years?

You may read that microscopes, powered files and warm filling materials have made root canals better. Current guidance supports some of this, but not all of it.

• The European guideline says treatment should use a dental dam, good light and magnification. The British Endodontic Society explains that a dental dam isolates the tooth, keeping saliva away and stopping small instruments from being lost.
• For people with an infection at the root tip, the guideline suggests using powered nickel-titanium files rather than traditional stainless-steel hand files. These are fine instruments made of a flexible metal, which clean and shape the canals. It grades this a weak recommendation, and found no evidence that any one type of powered file works better than another. It says several ways of filling the canals, cold or warm, may be considered.
• The British Endodontic Society says a dentist may refer a more complex tooth to a specialist, and that a specialist is likely to use an operating microscope.

What to expect afterwards

The anaesthetic can leave your jaw and face numb for several hours. The NHS says the area around the tooth may feel swollen and sore, and should get better in a couple of weeks. The Oral Health Foundation describes a tender feeling that lasts a few days. Ask a pharmacist, or your dentist, which pain relief is suitable for you.

A temporary filling is not meant to last. The British Endodontic Society says the tooth will need a permanent filling or crown, so go back for that appointment. Be careful not to bump your mouth and go to any follow-up appointments, the NHS advises. The European guideline recommends monitoring treated teeth for a prolonged period.

A crown may be needed if the tooth was badly infected, according to the NHS. The Oral Health Foundation explains that a tooth without a living nerve can become more brittle and more likely to break, so a crown may be advised if a filling would not be strong enough. It adds that a root-filled tooth can still decay if oral hygiene is poor, so it needs brushing and looking after like your other teeth.

How long does a root-treated tooth last?

A British Dental Journal study published in 2026 followed 791,375 root canal treated teeth in the NHS in England and Wales, all treated between 1990 and 2006.

• After 15 years, an estimated 83% had not been extracted.
• Counting retreatment, surgery or extraction, an estimated 77% had needed none of these.
• Lower teeth and back teeth did better than upper and front teeth, and the age of the patient also made a difference.

Nobody can promise how long a particular tooth will last, and your dentist can tell you what applies to yours.

When to see a dentist

A dental abscess will not go away on its own, says the NHS. It advises asking for an urgent dentist appointment, or getting help from NHS 111, if you think you have one.

Do not go to a GP surgery for a dental abscess: the NHS explains that it will not be able to give you dental treatment. Call your dentist. If you do not have one, or cannot get an emergency appointment, call 111 or use 111 online.

What we would do

The first step is an examination, such as a new patient exam: we look at the tooth, take small X-rays where needed and explain your options in plain language.

If root canal treatment is right for the tooth, it is done under local anaesthetic. We remove the infected pulp, clean the inside of the tooth, then fill and seal it. It generally takes one to two hours and sometimes needs more than one visit. You may have some soreness and sensitivity for a few days, and we recommend avoiding chewing on the tooth until it has healed. We often suggest a crown afterwards to protect it.

If the tooth cannot be saved, we can talk through a tooth extraction and the replacement options, such as a denture, bridge or implant.

If you are nervous, our nervous patients page explains how we support you, and we explain each step as we go. A tooth in severe pain may need to be seen sooner: our emergency dentist page explains how. Our price list shows what each type of root canal costs.

If a tooth has been sore, sensitive or swollen, book an appointment and tell the team what you have noticed.

Want us to take a look?

Book an appointment at whichever of our five practices suits you. We will check what is going on and talk you through your options.

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