Root Canal Treatment (Endodontics): Procedure

What is inside a tooth

Beneath the enamel and dentine there is a soft tissue called the pulp, which contains nerves and blood vessels and runs from the crown down through the roots. While the tooth is developing this tissue supplies it; once development is complete the tooth continues to be nourished from the surrounding tissues. When decay, a crack, repeated dental work or trauma allows bacteria to reach the pulp, it becomes inflamed, and because it is enclosed in a rigid space the pressure produces pain. Root canal treatment addresses this enclosed space.

How the need for treatment is established

A decision is not made from symptoms alone. The tooth is examined, its response to cold and to pressure is tested and compared with neighbouring teeth, and a radiograph is taken to look at the root ends and the surrounding bone. In some cases three-dimensional imaging is used where canal anatomy is complex. A tooth that no longer responds to testing may still need treatment even when it is not painful, which is why the assessment is made on the findings rather than on discomfort.

Treatment in one visit or several

Some cases are completed in a single appointment and others are spread over more than one. The difference is not a matter of preference: the number of canals, their shape, the state of the infection and whether the tooth has been treated before all affect it. Where infection is present, a medicament may be left inside the tooth between appointments. The plan is explained at the first visit, and it can change if the canal anatomy turns out to differ from what the radiograph suggested.

Retreatment and root-end surgery

A treated tooth can develop problems later, either because a canal could not be fully cleaned or because bacteria have re-entered through a leaking restoration. In that case the existing filling material is removed and the canal system is cleaned again. Where retreatment is not possible or has not resolved the finding, a small surgical procedure at the root end may be considered. Both are assessed with radiographs, and the tooth is followed up afterwards rather than considered finished.

Restoring the tooth afterwards

Root canal treatment removes tissue from inside the tooth, and a tooth that has lost structure is more prone to fracture under chewing load, particularly a back tooth. For this reason a crown is often part of the plan; the options are described on the crowns and veneers page. Whether a filling is sufficient depends on how much sound tooth structure remains. Leaving a treated back tooth without a definitive restoration is the situation most often associated with later fracture.

Root canal treatment in primary teeth

Baby teeth can also need treatment of the pulp, and the approach differs because the tooth is due to be replaced and the permanent tooth is developing beneath it. The materials and technique used are specific to primary teeth. Treating rather than removing a baby tooth keeps the space for the permanent tooth that follows; more on this is set out on the paediatric dentistry page.