Root canals are necessary when the pulp layer of a tooth becomes infected. Infection can lead to the loss of a tooth so it is necessary to remove the infection with root canal therapy. The procedure is generally comfortable and saves the natural tooth, prevents the spread of infection, and returns the smile to complete health.
There are two common causes of infection: cavities and fractured/broken teeth. Both expose the pulp area to bacteria that live in saliva. These bacteria can cause an infection that can kill the pulp.
Without treatment, pus from the infected tooth can spread to the root tip and eventually pass ot the jaw bone. This can cause an abscess (a pus pocket) that can damage the bone that surrounds the tooth. The pressure this causes can cause excruciating pain and, left untreated, can be life threatening. An infected tooth can not heal on its own and will only get worse.