A root canal is a treatment to remove the infected or inflamed pulp from the inside of a tooth. The pulp contains blood vessels, nerves, and connective tissue. Reasons for needing a root canal include deep tooth decay, cracks, injuries, or electively to better retain a crown. Left untreated, infection from the pulp can spread and cause bone loss around the tooth. During a root canal, an endodontist carefully cleans, shapes, and seals the inside of the tooth to prevent further infection.