What happens during root canal treatment: a step-by-step guide

Much of the anxiety about root canal treatment comes from not knowing what will happen. In practice it is a calm, methodical procedure that most patients describe afterwards as "no worse than a filling, just longer". This is what a typical appointment looks like at our practice.

Before the appointment

You will already have had a consultation, so you know the diagnosis, the plan and the fee. Eat normally beforehand — the appointment can last 60 to 90 minutes and you will not be able to eat comfortably for a few hours afterwards. Take your usual medication unless we have told you otherwise.

Step 1: numbing the tooth

Local anaesthetic is placed around the tooth. For lower back teeth this takes a few minutes to work fully, so we wait and test the tooth before starting. A hot, inflamed tooth can occasionally be harder to numb; if so, additional anaesthetic is placed directly where it is needed. You should feel pressure and vibration during treatment, never sharp pain — and if you do, raise a hand and we stop.

Step 2: the rubber dam

A thin sheet of rubber is stretched over a small frame and fitted around the tooth, held in place by a small clip. It feels unusual for a minute and is then easily forgotten. The dam keeps saliva away from the tooth, stops the disinfecting solutions reaching your mouth and protects your airway from small instruments. You can breathe and swallow normally throughout.

Step 3: opening the tooth

A small opening is made through the biting surface, or through an existing filling or crown, into the pulp chamber. Under the microscope the floor of the chamber is examined and the entrance to each canal is identified — including the extra canals that are easily missed without magnification.

Step 4: cleaning and shaping the canals

The length of each canal is measured with a small electronic device, confirmed with an X-ray where needed. Fine, flexible instruments are then used to remove the pulp tissue and shape the canal, while the canal is flushed repeatedly with a disinfecting solution. Ultrasonic activation drives the solution into the side branches that instruments cannot reach. This is the longest part of the appointment and the one that decides the result.

Step 5: filling the canals

Once clean, dry and shaped, the canals are sealed with a root filling material and sealer that fill the space completely. A final X-ray confirms the result. If the tooth was heavily infected, we may instead place an antibacterial dressing and complete the filling at a second visit a week or two later.

Step 6: sealing the tooth

The opening is closed with a strong temporary filling or, where possible, a permanent one. The rubber dam comes off and you are free to go.

After the appointment

Expect the tooth and gum to feel bruised for two or three days, particularly on biting; ordinary painkillers from the chemist are usually all that is needed. Avoid chewing on the tooth until it has its final restoration. Contact us if pain increases rather than settles, if a swelling appears or if the temporary filling comes out.

The final restoration

A root-treated tooth is sealed from below but still needs protecting from above. Your own dentist will place the final filling or, for most back teeth, a crown or onlay. Doing this promptly — within a few weeks — is one of the most important factors in how long the treatment lasts. We send your dentist a report with the X-rays and our recommendation.

How long will the tooth last?

With a thorough treatment and a well-made restoration, a root-treated tooth can last as long as any other. We review healing of the bone around the root on an X-ray at a later visit. For the questions people ask most often, see the root canal treatment page.