Root canal treatment usually involves the removal of the tooth’s pulp, a small, thread like tissue that was important for tooth development. Once removed, it is replaced with materials that seal off the root canal from bone supporting the tooth’s root. Years ago, teeth with diseased or injured pulps were removed. Today, root canal (endodontic) treatment enables dentists to save many teeth that otherwise would be lost. Treatment usually involves from 1-3 dental visits. In the final step, a crown is placed over the tooth.