Root canal treatment (also called a root canal) is done when decay will likely damage or has already killed a tooth. During a root canal, a dentist or endodontist removes the pulp from the center of a tooth and fills the pulp cavity. This can prevent the development of a painful infection in the pulp that may spread to other teeth. A root canal can also treat an infection that has developed into an abscessed tooth. This procedure can relieve toothache, stop infection, and promote healing. Whenever a tooth has had a root canal treatment, a crown must be placed on the tooth for protection.