How Long Does a Root Canal Take? Visits, Timing and Recovery

How many appointments, and how long each takes

The NHS says that root canal treatment usually takes 2 or more appointments¹, and that each appointment may last 1 to 2 hours, or sometimes longer. That describes usual practice in the UK health service, not a trial result, but it is a fair starting point.

The plan depends on the tooth. Back teeth have more canals than front teeth, and the canals can be narrow or curved, so they usually take longer. If there is an infection, the dentist may leave a medicine inside the tooth under a temporary filling and finish at a later visit.

The research we reviewed does not report how long each appointment takes. Any time in minutes is an estimate for a particular tooth, and your dentist can give you one after examining it.

What happens during treatment

1. Examination and X-ray. The dentist checks the tooth and the bone around the root.
2. Local anaesthetic. The tooth is numbed, so you stay awake. If you still feel pain, say so. In studies of patients who were already in pain before treatment, extra anaesthetic injections were often needed².
3. Isolating the tooth. A thin rubber sheet, called a rubber dam, is placed around the tooth to keep it dry and clean. The trials in the Cochrane review below all used one.
4. Cleaning the canals. The dentist opens the tooth, removes the inflamed or infected pulp, shapes the canals and rinses them with a disinfectant.
5. Medicine and a temporary filling, if needed. When the treatment is split over visits, the tooth is sealed with a temporary filling in between.
6. Filling the canals and sealing the tooth. The canals are filled and the tooth is closed with a filling. Some teeth then need a crown, which means further appointments after the root canal treatment itself.

One visit or several?

A Cochrane review of 47 trials compared finishing the treatment in one visit with spreading it over several. In the 13 trials that checked X-rays a year or more later (1,505 teeth), it found no clear difference in failure³, with moderate certainty. That does not prove the two are the same, but neither was shown to heal better.

There was one difference. People were somewhat more likely to report pain within the first week³ after one-visit treatment than after the first of several visits (moderate certainty). How strong the pain was up to 72 hours after the filling did not differ (low certainty), and there was no clear difference in swelling or flare-ups (very low certainty). The authors concluded that neither approach can prevent pain and other problems in the year after treatment.

So the number of visits is a practical decision about your tooth, not a question of which method is better. An infection that needs medicine between visits, or a tooth with many or difficult canals, are common reasons for more than one appointment.

Does it hurt, and how long does recovery take?

Pain is most common before treatment, not after it. A review of pain in root canal treatment averaged the studies that measured it at each point²: the share of patients with pain was 81% before treatment (30 studies), 40% a day after (11 studies) and 11% a week after (12 studies). The severity of the pain also fell sharply within a day. These are averages across studies, not your personal chance.

The NHS says the area may feel swollen and sore¹ afterwards, but it should get better in a couple of weeks. It suggests paracetamol or ibuprofen if you are in pain. Follow your dentist's advice on pain relief, do not go over the maximum daily dose, and swallow the tablets⁴ rather than holding one against the gum. If you are managing the pain yourself and still need painkillers after 24 hours, ask a pharmacist or your dentist.

A flare-up means severe pain or swelling that needs an extra visit, usually within the first week. A review of 15 studies with 24,320 cases found this in about 3 in 100 cases⁵, ranging from under 1 to about 9 in 100 between studies. Flare-ups were more common when the tooth hurt on its own, or when tapping it hurt, before treatment. Each of those findings comes from only three non-randomised studies, so they are uncertain.

How long the tooth lasts afterwards

In pooled studies, about 86 to 93 in 100 root-treated teeth were still in place⁶ 2 to 10 years after treatment; most of the studies looked back at patient records. Still in place does not mean trouble-free. Complete healing seen on an X-ray is a different, stricter measure: a review of studies published between 1922 and 2002 found pooled success rates of 68% to 85%⁷ on the strictest criterion. The two sets of figures come from different studies and cannot be compared directly.

Teeth that received a crown after treatment survived longer in observational studies. The one trial in a Cochrane review that compared a crown with a filling could not show a difference⁸ in failures after 3 years. It was small (117 people), included only premolars restored with a post and had a high risk of bias, so it cannot show that the two do equally well. Whether your tooth needs a crown depends on how much of it is left.

When to contact your dentist

Contact your dentist if, after treatment:

• pain or swelling gets worse instead of better, or becomes severe;
• soreness has not settled after a couple of weeks;
• the temporary filling comes out or the tooth breaks.

Ask for an urgent appointment if your face, cheek or jaw becomes swollen or you have a high temperature.

Before treatment, see a dentist if toothache lasts more than 2 days or does not go away with painkillers⁹.

Emergencies. Call 112 or go to the nearest emergency department if you have swelling that makes it hard to breathe, speak or swallow, a swollen or painful eye or sudden problems with your eyesight, swelling in your neck, a lot of swelling inside your mouth¹⁰, or if you find it hard to open your mouth.

Frequently asked questions