Your dentist will perform a root canal treatment to restore a badly impaired or infected tooth. Throughout the process, the damaged area of the tooth is cleared, the remainder of the tooth is cleaned, disinfected and then a filling is applied and sealed to enhance and strengthen the remaining portion of the tooth. Tooth decay is the primary reason many patients may require root canal therapy. While the decay advances heavily into the tooth, it ultimately extends to the nerve. At this point, the best method to correct and restore the tooth, will be by undergoing root canal (or endodontic) treatment.