The nonsurgical endodontic retreatment is one of greatest challenges in everyday's endodontic practice. Clinical procedures, in general, include the removal and/or drilling of crowns, the removal of cast posts or screws, gutta-percha, silver cones, pastes, and, in some cases separated instruments. Once these maneuvers are done, we must approach the root canal system to be able to shape it again, clean it, and finally fill it. The diagnosis must encompass a vision, not only endodontic but also restorative. This means that the dentist and/or endodontist should be trained to do an endo-restorative diagnosis of the tooth, considering if retreatment is viable and if it will be structurally able to fulfill its functional role in the oral cavity after therapy. The bibliography describes a success rate in the endodontic reintervention that oscillates between 80% and 88%, being in this way a predictable practice, when it is well executed and fundamentally when diagnosis is correct.