When a tooth becomes infected or severely inflammed, the inside nerve must be taken out in order to preserve the tooth. The treatment is called a root canal because inside of the roots of the tooth are small canals that house the pulp (nerve/blood supply). The pulp must be removed and the infection treated, or the surrounding tissues will also become infected and the tooth might be lost entirely.
Before doing a root canal, the doctor will completely numb the tooth and surrounding area so that it can be treated in a comfortable and painless way. After removing the tooth pulp with small specialized instruments and treating the infection with antibacterial medications and solutions, the doctor will fill and seal the roots and tooth to help avoid future reinfection. Likely the tooth will need to be covered with a crown in order to protect and strengthen it. The root canal procedure is completed in normally one or two visits. For those who are extremely anxious about root canal therapy, sedation is available (see sedation/sleep dentistry).