A root canal is a treatment used to repair and save a tooth that is badly decayed or becomes infected. During a root canal procedure, the nerve and pulp are removed and the inside of the tooth is cleaned and sealed. Without treatment, the tissue surrounding the tooth will become infected and abscesses may form.This therapy usually involves local anesthesia and may be completed in one or more visits depending on the treatment required. Success for this type of treatment occurs in about 90% of cases.