Root canal treatment is needed for two main reasons. The first is infection. An untreated cavity is a common cause of pulp infection. The decay destroys the enamel and dentin of the tooth until it reaches the pulp. Bacteria then infect the pulp. Antibiotics can't get to infections inside teeth. The inflammation caused by the infection reduces the blood supply to the tooth. The reduced blood supply also keeps the pulp from healing.

The second reason for a root canal is damage to the pulp that can't be fixed. A fracture in a tooth can damage the pulp. Multiple fillings or other restorations on the same tooth also can damage the pulp.

When the pulp is inflamed but not infected, it may heal on its own. Dentist may want to see if this will happen before doing root canal treatment. If the pulp remains inflamed, it can be painful and may lead to infection.

An infection in the pulp can affect the bone around the tooth. This can cause an abcess to form. The goal of root canal treatment is to save the tooth by removing the infected or damaged pulp, treating any infection, and filling the empty root canals with a material called gutta percha.

If root canal treatment is not done, an infected tooth may have to be extracted. It is better to keep your natural teeth if you can. If a tooth is missing, neighboring teeth can drift out of line. Keeping your natural teeth also helps you to avoid other treatments, such as implants or bridge. Also, if you ignore an infected or injured tooth the infection can spread to other parts of your body.

Once a tooth is treated, and restored with a filling or crown, it often will last the rest of your life.