What Happens During Root Canal Treatment? A Step-by-Step Guide

Root canal treatment has a reputation it does not deserve. Carried out with modern anaesthesia, magnification and technique, it is a controlled, methodical procedure that relieves pain rather than causing it. Knowing what happens at each stage takes much of the anxiety out of the appointment.

Before the appointment

You can eat normally beforehand — in fact it is better not to arrive hungry, as the appointment may last up to 90 minutes. Take any regular medication as usual and tell us about any medical conditions, allergies or blood-thinning medicines. If you feel anxious, say so; we can pace the appointment to suit you.

Step 1: Numbing the tooth

The tooth and surrounding gum are numbed with local anaesthetic. For a tooth with a very inflamed pulp we sometimes use additional or supplementary techniques to make sure the tooth is completely numb before starting. You should feel pressure and vibration during treatment, but not sharp pain — if you do, tell us and we will stop and top up the anaesthetic.

Step 2: Isolating the tooth with rubber dam

A thin sheet of rubber is stretched over the tooth and held in place with a small clamp. Many patients find it makes the procedure more comfortable, because there is no water or instruments in the rest of the mouth, and you can swallow normally. More importantly, the rubber dam keeps saliva and bacteria away from the inside of the tooth and prevents you swallowing or inhaling anything. It is a standard of care in specialist endodontics.

Step 3: Opening the tooth

A small opening is made through the biting surface (or the back of a front tooth) to reach the pulp chamber. Working under the operating microscope, the endodontist identifies the entrances to each root canal. Molars usually have three or four canals, sometimes more, and finding all of them is one of the main reasons specialist treatment is more predictable.

Step 4: Cleaning and shaping the canals

Fine flexible instruments are used to remove the pulp tissue and shape each canal from the chamber to the tip of the root. An electronic device measures the exact length of each canal so that the whole canal is treated without going beyond the root. Throughout this stage the canals are flushed with antibacterial solutions, which are activated with ultrasonic energy to reach into side branches and irregularities that instruments cannot.

This is usually the longest part of the appointment. You may hear a soft beeping from the length-measuring device and feel gentle vibration.

Step 5: Medicating the tooth (if a second visit is needed)

If the tooth had an active infection, or the anatomy is complex, an antibacterial dressing may be placed in the canals and a temporary filling put over the opening. The dressing keeps working between appointments and gives the surrounding tissues time to settle. Most straightforward cases, however, are completed in a single visit.

Step 6: Filling the canals

Once the canals are clean, dry and shaped, they are sealed with gutta-percha — a soft, rubber-like material — together with a sealer that fills any remaining space. The aim is to seal the canal system completely so that bacteria cannot re-enter. A radiograph confirms the root filling is at the right length.

Step 7: Sealing the opening

The access opening is closed with a filling. Depending on the plan agreed with your dentist, this may be a permanent bonded filling or a temporary one that your dentist replaces when placing the final restoration.

After the appointment

The numbness wears off after two to four hours. Mild tenderness for a few days is normal — the tissues around the root have been working hard — and over-the-counter painkillers such as ibuprofen or paracetamol are usually enough. Avoid chewing hard foods on the tooth until it is permanently restored.

The final restoration

A root-treated back tooth is more brittle than an untreated one and usually needs a crown or onlay to protect it from fracture. Arranging this promptly with your dentist is one of the most important factors in how long the tooth lasts.

If you have questions about any of these steps, ask at your consultation — we are always happy to explain.