Root canals are tiny passageways in the center of the tooth and contain the tooth's nerves and blood vessels and extend the entire length of the tooth, to the tip of the root. All teeth have between one and five root canals.
Many tooth problems involve infections that start as a small cavity and grow over time. The infection (cavity) spreads to the tooth's root canal space, and as the infection continues, a toothache often develops. Root canal therapy is usually indicated in this case and involves removing the nerve from the tooth and placing a filling in the empty root canal space. A traumatic injury to a tooth can also compromise the nerve, leading to similar problems.