Revision of endodontic treated teeth is a common problem. In this clinical case Dr. Josepf Diemer und Dr. Wolf Richter/Germany demonstrate their approach step by step. Since the marginal conditions of the existing restoration are clinically acceptable, the crown is left in place and a trepanation conducted to gain access to the root canal. A second canal, which had not been instrumentalized before, is found during the treatment. For the removal of the old gutta percha filling and the shaping of the two canals manual instruments as well as the files of the ProTaper System are used. Frequent irrigation with sodium hypochlorite solution is important during the root canal preparation. Since bacteria are involved in this case, the operator also uses Chlorhexidin for the disinfection of the canal system. For the new canal filling the Epiphany® Endodontic Obturation System is used. This thermoplastic material looks like gutta percha. However, with the Epiphany System, the obturators bond to their associated sealer, that has been thoroughly applied before.