A tooth has between one and four root canals, which contains the nerves, blood and lymph vessels (also known as the pulp).
When the pulp becomes infected, usually from a deep cavity or fracture that allows bacteria to creep in, or injury due to trauma, it can die. Damaged or dead pulp causes increased blood flow and cellular activity, and pressure cannot be relieved from inside the tooth. Pain in the tooth is commonly felt when biting down, chewing on it and applying hot or cold foods and drinks.
Root canal therapy is performed in order to save the tooth. The procedure involves cleaning out the diseased pulp and permanently sealing the tooth. Typically a crown is used to restore the tooth to its original shape and function.
In most cases, a root canal is a relatively simple procedure with little or no discomfort involving one to three visits.
Root canals have an extremely high rate of success (usually higher than 95 percent).