Your Guide to Root Canal Treatment
A clear guide to root canal treatment: what it is, why you might need it, and what happens before, during and after your treatment.
Urgent help: who to contact
Call 999 or go to A&E now if you have severe swelling spreading to your neck, the floor of your mouth or your eye area, or if you find it hard to breathe or swallow. Dental infections can spread fast and become serious.
Contact your dental team if you develop a high fever (above 38°C). If you cannot reach them, call NHS 111.
What is root canal treatment?
Root canal treatment (endodontic treatment) removes infected or damaged tissue from inside a tooth. Each tooth has one or more thin channels inside its root. These are called root canals. They hold the dental pulp. The pulp is soft tissue made of nerves and blood vessels.
An infected or inflamed pulp cannot heal on its own. Root canal treatment cleans out the canals, kills the germs in them, and seals them. This lets you keep your own tooth instead of having it taken out.
Why might I need root canal treatment?
The pulp inside a tooth can become infected or damaged for several reasons:
- Deep decay. Germs (bacteria) from a large hole reach the pulp.
- A cracked or broken tooth. This lets bacteria get into the tooth.
- Repeated dental work. Many fillings in the same tooth can irritate the pulp over time.
- An injury. A knock to a tooth can damage the pulp. This can show up months or years later.
Common signs include:
- severe toothache
- pain from hot or cold that lingers
- the tooth turning a darker colour
- swelling of the gum near the tooth
- a spot on the gum that keeps coming back
Sometimes there are no signs at all. The problem is then found on an X-ray.
What are my alternatives?
The main alternative to root canal treatment is taking the tooth out. If the nerve is inflamed but still alive, you may sometimes be offered a pulpotomy instead. This removes only the inflamed part of the nerve, then seals the tooth. Once the nerve has died or become infected, the choice is usually between root canal treatment and taking the tooth out.
- Root canal treatment. This saves your own tooth. Your own tooth is almost always better than a false one.
- Taking the tooth out (extraction). This ends the infection quickly but leaves a gap. Replacing the tooth with an implant, bridge or denture means more cost and more treatment.
- No treatment. A dental infection will not clear up without treatment. It is likely to spread and cause more pain. You may need emergency treatment. Leaving an infected tooth untreated is not safe.
Your dental team will help you understand which option suits your tooth and your situation best.
What does root canal treatment involve?
Root canal treatment usually takes one or two appointments. Here is what to expect:
- Numbing injection (local anaesthetic). The tooth and the area around it are numbed. Despite its reputation, most people find root canal treatment no worse than having a filling.
- Rubber sheet (rubber dam). A thin rubber sheet is placed around the tooth. It keeps the tooth clean and dry.
- Opening the tooth. Your dental team makes a small opening in the top of the tooth to reach the root canals.
- Cleaning and shaping. Very fine tools remove the infected pulp and clean each canal. Germ-killing liquids are used to wash out the canals.
- Temporary filling. If treatment takes two visits, a temporary filling (dressing) keeps the tooth clean in between.
- Root filling. When the canals are clean and dry, they are filled and sealed. A rubber-like material (gutta-percha) is used with a sealing paste.
- Repairing the top of the tooth. In most cases, a crown is advised afterwards. Root-treated teeth can become more brittle over time, and a crown helps stop them cracking.
Risks and possible problems
Root canal treatment works well in most cases. Studies suggest around 85–95% of root-treated teeth still work after 10 years. But like all dental treatment, it has some risks.
Common (affect more than 1 in 10 people):
- Soreness and tenderness around the tooth for several days after each visit
- Mild swelling of the gum
- Treatment may not fully resolve the infection. You may then need another course of treatment or a small operation (apicectomy).
- Late failure over time. Over about 10 years, around 1 in 10 root-treated teeth need treating again or taking out.
Uncommon (affect about 1 in 10 to 1 in 100 people):
- A fine tool may sometimes break inside a root canal. Your dental team will tell you if this happens and talk through your options.
Rare (affect fewer than 1 in 100 people):
- A hole made in the side of the root (perforation) during treatment
- An allergic reaction to the materials used (very uncommon)
Even after successful treatment, a root-filled tooth may not last for life. Regular check-ups and good cleaning are vital for it to last.
What to expect after treatment
The tooth often feels tender or sore for a few days after treatment. This is normal. Painkillers from a pharmacy, such as ibuprofen or paracetamol, usually help. Adults: follow the dose on the packet. Children: use children's paracetamol or ibuprofen and give the dose on the packet for their age. Check with a pharmacist, dentist or doctor before you take ibuprofen if you have asthma, have had a stomach ulcer, have heart, kidney or liver problems, take blood-thinning medicines, or are pregnant.
- Do not chew on the treated tooth until it has its permanent crown or filling.
- Keep brushing and flossing as normal.
- Go to your follow-up appointment. It checks healing, and it is when the permanent crown or filling is placed.
Contact the practice if you have:
- severe pain that painkillers do not control
- swelling that is getting worse
- a high temperature
Questions to ask your dental team
- How many root canals does this tooth have? How simple is treatment likely to be?
- How many appointments will I need?
- What are my chances of keeping this tooth in the long term?
- Will I need a crown afterwards, and how soon?
- What are the signs that treatment has not worked?
This leaflet is for general information only and does not replace professional dental advice. It is intended to support — not replace — the discussion with your dental team about your individual options, risks, and treatment plan. Treatment outcomes vary between patients depending on individual circumstances. Your dental team will confirm exact fees and what is suitable for your specific circumstances before you agree to any treatment.
Sources
- A guide to Good Endodontic Practice, 1st edition. British Endodontic Society, 2022.
- Root canal treatment. NHS website (nhs.uk), reviewed October 2025.
Links checked 18 October 2026.
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