If the nerve inside a tooth is necrotic or becomes infected, root canal (endodontic) treatment would be indicated.  Prior to starting treatment, the nerve of the affected tooth is assessed, as well as the restorability of the tooth.  Radiographs are also important as a diagnostic tool to check for root fractures, abscesses, and other pathology.  Once the root canal is completed, in most cases a crown is recommended to prevent the tooth from breaking.