Patient guide · Root Canal Treatment
Root canal treatment: what it is, why you may need it, and what happens next
Root canal treatment can save a tooth when the soft tissue inside it has become irreversibly inflamed or infected. Here is how we diagnose the problem, what the treatment involves, and why rebuilding the tooth afterwards matters.
The short version
We remove inflamed or infected tissue from inside the tooth, clean and seal the root canals, then restore the tooth so you can use it again. Some cases take one appointment; others need more than one. The exact plan depends on the tooth, its anatomy, existing damage and symptoms.
What is a root canal?
Inside each tooth is a small space containing the pulp — nerves, blood vessels and connective tissue. The narrow passages running through the roots are the root canals. Root canal treatment removes unhealthy pulp, cleans and shapes those passages, and seals them. The aim is to keep your natural tooth when it can be restored predictably.
The root canal procedure treats disease inside the tooth. The visible part of the tooth still needs a sound final restoration, which may be a filling, onlay, overlay or crown.
How can a tooth’s nerve die?
The nerve and blood supply are part of the tooth’s pulp. Injury can cause inflammation. Early inflammation may settle if its cause is treated; if the pulp cannot recover, its blood supply can fail and the tissue may die (pulp necrosis).
Deep decay, cracks and trauma
Deep decay: when decay has travelled through enamel into deep dentine—sometimes called a D3 lesion in a charting system—bacteria and their by-products can irritate the pulp. A D3 label alone does not mean the nerve is dead or that root canal treatment is inevitable. Depth, symptoms, pulp tests and an X-ray help guide the diagnosis.
Trauma: a knock or fall may damage the tiny blood vessels entering at the root tip, even when the tooth looks unbroken. The pulp may recover, or it can lose vitality weeks or months later.
Cracks and repeated work: a crack, large restoration or repeated procedures can also leave the pulp unable to recover. A dead pulp may become infected; bacteria in the canals can then inflame the tissues around the root tip, sometimes creating an abscess or a dark area on an X-ray. Pain is not always present.
Why might treatment be needed?
Deep decay, a crack, trauma, or repeated dental work can irritate or expose the pulp. Sometimes the inflammation settles; sometimes it cannot recover. Once the pulp dies or becomes infected, bacteria can travel through the root canals and cause inflammation around the root tip.
Possible clues include lingering sensitivity to hot or cold, pain on biting, spontaneous or night pain, swelling, or a small pimple on the gum. A tooth can also need treatment with little or no pain. None of these signs alone confirms the diagnosis.
How we decide
We review your history, examine the tooth and surrounding tissues, test its response to cold and tapping, assess the bite and existing restorations, and take appropriate X-rays. In selected complex cases, three-dimensional imaging may add useful information. We also assess whether enough healthy tooth remains to rebuild it.
What happens to an infection at the root tip?
When bacteria leave an infected canal through the root tip, the surrounding tissues become inflamed and local bone can be lost. On an X-ray, this may appear as a dark area. Cleaning and sealing the canal removes the source of infection so the body can repair the area.
Educational illustration, not a patient X-ray. The four panels show an infected tooth, cleaning the canals, filling and sealing them, and an example of a crowned tooth with healed supporting bone. Healing differs between teeth and takes time; complete bone repair can take longer than six months. Follow-up examination and X-rays are used to judge progress. The final restoration is chosen for the individual tooth.
What are the choices?
After diagnosis, the options may include root canal treatment to retain the tooth, extraction with a discussion of whether and how to replace it, or monitoring only when that is clinically reasonable. A tooth with a deep fracture, poor support or too little restorable structure may not be suitable for root canal treatment. We explain the likely prognosis and alternatives before you decide.
Antibiotics may be prescribed for particular spreading infections, but they do not remove the source of infection inside a tooth. Definitive dental assessment and treatment are still needed.
What happens during the appointments?
1. Make the tooth comfortable and isolate it. Local anaesthetic is usually used. A rubber dam isolates the tooth from saliva while we work.
Rubber dam isolation: the light-blue sheet keeps saliva away from the tooth during treatment. Clinical photograph by Giulio Arnaboldi, Wikimedia Commons, CC BY-SA 4.0; no changes. This is an educational example, not a Burleigh Dentistry patient case.
2. Access and clean the canals. We make an opening through the biting surface or back of the tooth, remove the inflamed or infected pulp, find the canals, then clean and shape them. We use disinfecting solutions and check the canal lengths.
3. Seal the canal system. Once the canals are ready, they are filled and sealed. If treatment needs more than one visit, medication and a temporary filling may be placed between appointments.
4. Rebuild the tooth. A secure final restoration seals the access and protects the remaining tooth. We plan this early, particularly for a heavily filled molar or a cracked tooth.
Appointments vary in length and number. Curved or narrow canals, infection, previous root canal treatment, or a difficult-to-restore tooth can make the process more involved. Sometimes referral to an endodontist is appropriate.
Will it hurt?
Local anaesthetic is intended to make treatment comfortable. An acutely inflamed tooth can sometimes be harder to numb, and we will check your comfort and adjust the approach if needed. It is common to have tenderness when biting for a few days afterwards, especially if the tooth was painful or infected before treatment. It should trend towards improvement.
What happens next?
While numb: avoid biting your lip or cheek. Follow the instructions given for your particular tooth. If it has a temporary filling or has not yet received its final restoration, avoid hard chewing on that side.
Final restoration: do not leave a temporary filling in place indefinitely. A well-sealed restoration helps protect against leakage and fracture. Back teeth with substantial structural loss often need cuspal coverage; a relatively intact front tooth may need less. The decision depends on what remains, not simply on whether a root canal was performed.
For the detailed restoration decision, read our companion guide: You’ve Had a Root Canal Treatment — Now What?
Review: symptoms and the bone around the root may take time to settle. We may recommend clinical or X-ray review to check healing and the restoration.
How successful is root canal treatment?
There are two useful ways to judge an outcome. Tooth survival means the tooth is still present and functioning. Healing means symptoms have settled and any infection around the root tip has resolved or is resolving on review images. A tooth can remain in use while the bone is still healing.
In a 2024 review of studies of root-filled back teeth, about 91% remained in place after 4–7 years and 87% after 8–20 years. These are pooled research figures, not a prediction or guarantee for an individual tooth. Studies differ in the teeth treated, follow-up and definitions of success. Read the review.
The outlook for your own tooth depends on whether infection was already present at the root tip, canal anatomy, a crack or fracture, gum and bone support, how much sound tooth remains, and whether the final restoration protects and seals it well. We assess those factors before recommending treatment and review healing afterwards.
What if the infection does not heal?
A dark area on an X-ray at an early review does not automatically mean failure; bone repair can take time. If symptoms persist, the area enlarges or healing stalls, we reassess the diagnosis, tooth restorability and root canal filling. Options may include continued monitoring where appropriate, root canal retreatment, an apicoectomy (root-end surgery), or extraction if the tooth cannot predictably be maintained.
During an apicoectomy, an endodontist or appropriately trained clinician accesses the root tip through the gum, removes inflamed tissue and the very end of the root, and places a small root-end filling to seal it. It is generally considered when conventional retreatment is unlikely to address the problem or has not succeeded. Surgery has its own risks and prognosis, so the options should be considered for the specific tooth. See the American Association of Endodontists’ explanation.
When should you contact us?
Call if pain is severe or increasing rather than settling, swelling develops, the temporary filling comes out, the tooth or restoration fractures, or your bite feels markedly high. Seek urgent medical care for swelling with difficulty breathing or swallowing, or swelling spreading towards the eye or neck.
Root canal treatment has a good chance of retaining a suitable tooth, but no treatment can guarantee it will last forever. Cracks, persistent infection, reinfection or later fracture can require further treatment or extraction. Good home care, the final restoration and regular reviews all matter.
Questions patients often ask
Can a tooth without pain still need treatment?
Yes. A pulp that has died may no longer respond to cold or cause toothache, while infection around the root remains visible on an X-ray or appears as swelling. Diagnosis depends on examination and tests, not pain alone.
Does every root-canal-treated tooth need a crown?
No. The tooth position, remaining structure, cracks and bite determine the restoration. Read how we decide between a filling, onlay, overlay and crown.
Can it be done in one visit?
Sometimes. Other teeth need staged care because of infection, complex anatomy or time needed to clean and seal them properly. We will explain the likely sequence for your tooth.
Start with a diagnosis
If you have a painful, cracked or heavily restored tooth, we can assess whether it can be saved and what restoring it afterwards would involve. You can make a decision with the full treatment plan in view.
Further reading: NHS root canal treatment · American Association of Endodontists