A tooth consists of two main parts: the crown, which is visible in your mouth and is contacted during chewing; and the root, which is typically not visible in your mouth and is anchored by surrounding bone and gum tissue. Inside each root are one or more channels that run the length of the root, this is the root canal space.
Contained within the canal(s) are blood vessels, nerves, and soft tissue that are collectively called the pulp. The pulp can be irreversibly injured or infected due to deep restorations, decay, fracture, trauma, or periodontal disease. Symptoms of pulpal involvement may include temperature or percussion sensitivity, spontaneous or radiating pain, and swelling.