Root canal treatment: steps, pain and aftercare

Pain that wakes you up at night, a tooth that throbs with hot drinks, an abscess: your dentist suggests a "root canal". This treatment saves a tooth whose nerve is too damaged to heal. This guide explains why it is done, what happens step by step, what you feel during and after, and what can be done if it fails, based on published reviews of the evidence. It is for information only and does not replace an examination.

What is the pulp, the "nerve" of the tooth?

Under the enamel and dentine, every tooth contains soft tissue called the pulp, which people usually call the "nerve". It runs down into the root through one or more thin canals: often one in a front tooth, three or four in a molar.

Root canal treatment means removing this pulp, cleaning and disinfecting the canals, then sealing them. The tooth stays held in the bone by its attachments, and it can keep working for many years if it is well restored.

Why would a tooth need a root canal?

A root canal is needed when the pulp cannot heal, or has already died:

deep decay that has reached the nerve (see the tooth decay guide);
irreversible pulpitis: the nerve is so inflamed that it will not recover;
a dead nerve or an abscess at the tip of the root, when bacteria have settled in the canals;
a knock to the tooth (a fall, a blow, sport), which can kill the nerve, sometimes months later;
a crack or fracture that reaches the nerve.

Root canal signs and symptoms

Only an examination, with tests and an X-ray, can tell whether the nerve needs to be removed. These signs mean you should see a dentist soon:

What you notice	What it may mean
Pain that comes on by itself, or wakes you up at night	Inflamed nerve, often irreversibly
Pain that lasts several minutes after hot or cold	Inflamed nerve
Pain when biting, a tooth that feels "longer"	Inflammation or infection at the tip of the root
Swollen gum, a small pimple of pus that keeps coming back	Abscess
A tooth that turns grey or dark, often after a knock	Dead nerve, even without pain

Pain that suddenly stops does not mean all is well: the nerve may have died, and the infection can carry on silently (see the toothache guide).

Go to the emergency department straight away if you have facial swelling spreading towards the eye or neck, fever, or difficulty swallowing, breathing or opening your mouth.

How is a root canal done?

Examination and X-ray: the dentist checks the nerve, the root and the surrounding bone, and tells you whether the tooth can be saved and rebuilt.
Local anaesthetic: when the nerve is very inflamed, numbness can be harder to achieve, and an extra injection is often helpful (Pak and White, 2011, PubMed). Say so if you can still feel something.
Rubber dam: a thin, flexible sheet isolates the tooth from saliva and bacteria.
Opening the tooth, after removing the decay, to reach the nerve.
Cleaning and shaping the canals: the pulp is removed, the length of the canals is measured, then they are widened with fine files and rinsed with a disinfecting solution.
Filling the canals: they are filled to the end of the root with a rubbery material (gutta-percha) and a sealer, so bacteria cannot come back.
A check X-ray, then the tooth is closed with a temporary dressing or a permanent restoration.

A review found that results are better when the canals are filled densely, without gaps, to within about 2 mm of the root tip, and when the tooth then gets a good-quality restoration (Ng et al., 2008, PubMed).

One visit or two?

Both are possible. With an infection or difficult canals, the dentist may leave a disinfecting paste in the canals under a temporary filling and finish at a second visit.

The Cochrane review, which brought together 47 studies and 5,693 teeth, found no difference in success on X-ray between one and several visits. People treated in a single visit were slightly more likely to report pain during the following week, with no difference in painkiller use (Mergoni et al., 2022, PubMed). The choice therefore depends on the tooth and the infection.

The cost depends on the tooth (number of canals), its condition and the restoration needed afterwards; it is explained before any decision.

Do root canals hurt?

Honestly: most of the time, the strong pain comes before the treatment, not during it. Under anaesthetic, most people mainly feel vibration, pressure and the discomfort of keeping their mouth open. A very inflamed tooth may still be sensitive at first: the anaesthetic is then topped up.

A review of 72 studies measured pain before and after treatment: about 81% of patients had pain before treatment, 40% the next day and 11% a week later, and the intensity dropped clearly from the first day (Pak and White, 2011, PubMed).

Aftercare: tooth pain after a root canal

The tooth may be tender when biting for a few days: the inflammation around the root tip is settling.
Chew on the other side until the tooth has its permanent restoration, and avoid hard and sticky foods: it can crack.
For pain, ask a pharmacist or doctor for a painkiller suited to your situation and your medicines.
Antibiotics do not replace treatment. The Cochrane review found no study testing an antibiotic alone, without cleaning the tooth; and when the tooth was treated, adding an antibiotic made no clear difference to pain or swelling (Cope et al., 2024, PubMed). They are only prescribed after an examination, in specific cases.

Call the practice if the pain gets worse instead of better after two or three days, lasts more than a week, if swelling appears or the temporary filling falls out. If swelling spreads, or you have fever or difficulty swallowing or breathing, go to the emergency department.

Root canal and crown: why rebuild the tooth?

A root-filled tooth has often lost a lot of structure: it can crack, and a restoration that leaks lets bacteria reinfect the canals.

A review of 14 studies found that a crown after treatment was the factor most strongly linked to keeping the tooth (Ng et al., 2010, PubMed).
But the Cochrane review, which found only one trial directly comparing a crown with a filling, concludes that there is not enough evidence to say which is better (Sequeira-Byron et al., 2015, PubMed).

In practice, a heavily filled molar often gets a crown; a front tooth with little damage may only need a bonded filling. The decision is made tooth by tooth.

How long does a root canal last? Success and failure

Success rates are high, but never guaranteed.

Healing: using strict criteria (the infection has completely gone on the X-ray, at least a year later), pooled success rates ranged from 68% to 85% (Ng et al., 2007, PubMed). They are better when there is no infection at the root tip yet.
Keeping the tooth: 86% to 93% of treated teeth were still in place 2 to 10 years later (Ng et al., 2010, PubMed).

What happens with a failed root canal?

If the canals become reinfected (pain when biting, a pimple of pus, a lesion on the X-ray), there are three options depending on the tooth:

Retreatment: the old root filling is removed, the canals are cleaned again and resealed. A review found a success rate of about 77% (Ng et al., 2008, PubMed).
Apical surgery: under local anaesthetic, the root tip is reached through the gum, removed, and the canal is sealed from below. Pooled success was 91% in trials and 78% in follow-up studies, over 2 to 13 years (Pinto et al., 2020, PubMed).
Extraction, when the root is split or the tooth can no longer be restored.

Root canal or extraction?

When a tooth can be kept and restored, a root canal keeps your own root. A review of 143 studies found similar long-term survival for a root-filled, restored tooth and for an implant with a crown (Torabinejad et al., 2007, PubMed).

A dental implant becomes a good option when the tooth cannot be saved. The choice is made after an examination; the timing and cost are explained before any decision.

What about baby teeth?

A baby tooth whose nerve is affected can often be kept. The dentist can do a pulpotomy (removing only the nerve in the crown of the tooth) or a pulpectomy (removing the whole nerve), often followed by a small crown. The Cochrane review concludes that these treatments are generally successful, with few failures (Smaïl-Faugeron et al., 2018, PubMed). Keeping the baby tooth keeps the space for the adult tooth.

Booking an appointment

Consultations take place in Rabat, Monday to Friday from 9 am to 6 pm and on Saturday from 9 am to 2 pm; the address is given when you book. The easiest way is to send a WhatsApp message saying which tooth hurts, the type of pain (at night, with heat, when biting) and how long it has lasted. See the appointment section. If you have an emergency sign, or outside these hours, go straight to the emergency department.

Frequently asked questions

What is root canal treatment?

It is a treatment that removes the damaged or infected nerve from inside a tooth, cleans and disinfects the root canals, then seals them, so that the tooth can be kept instead of being taken out.

How long does a root canal take?

A visit often takes around an hour, sometimes longer for a molar with three or four canals; treatment is done in one or two visits, and the permanent restoration may need one or more further appointments.

Why does my tooth hurt after a root canal?

Tenderness when biting is common for a few days while the area settles; pain that gets worse, lasts beyond a week, or comes back later with swelling may point to reinfection, a crack or a leaking restoration, and needs an examination with an X-ray.

Can a root canal get infected again?

Yes, sometimes, especially if bacteria get back in through a leaking or broken restoration; signs include pain when biting, swelling or a pimple of pus on the gum, and retreatment or surgery can often still save the tooth.

Can I have a root canal when pregnant?

Yes: guidelines agree that dental treatment, including emergency care, can be provided at any stage of pregnancy (Bao et al., 2022, PubMed); tell your dentist you are pregnant so that X-rays, anaesthetic and timing are adapted, with your doctor if needed.

Does a root canal on a front tooth need a crown?

Not always: a front tooth with little damage can often be restored with a bonded filling, while a crown is more often needed when much of the tooth is lost; a tooth that darkens can sometimes be lightened from the inside (see the teeth whitening guide).

Can antibiotics avoid a root canal?

No: they do not clean the inside of the tooth, and the pain or abscess comes back as long as the canals are not treated.