When cavities spread deep into the tooth or a tooth becomes cracked, bacterial may enter the nerve and cause server pain and infection. An abscess may form. A successful root canal treatment allows the patient to save the tooth as oppose to taking it out. Root canal therapy (endodontic treatment) is a process during which the nerve and blood supply are removed from the tooth. The area normally occupied by the nerve of the tooth, also called the pulp is then filled and sealed by a filling material. Keeping your tooth helps to prevent your other teeth from shifting.