Book excerpt: • When is a treatment considered ineffective? • How is a failed treatment diagnosed radiologically? • Is a retreatment always indicated? • What are the best solutions for correct disinfection and irrigation? • Which are the most appropriate obturation techniques in retreatments? • When should a lesion of apical origin be considered resolved? • What type of restorations may be performed in teeth with retreatments? • Which are the most appropriate techniques for the removal of endocanalar materials? • Can endodontic surgery be a first therapeutic choice? • When can a post-extraction implant be performed? The ten chapters of the volume answer these ten fundamental questions and the clinician who faces an apical pathology of endodontic origin will therefore have the solutions. The aim of this text/atlas is to provide a guide to the diagnostic approach and to the execution of endodontic retreatments of complex cases. The book is enriched by over 150 clinical cases by world-famous authors of various nationalities and illustrated with a high-quality iconography, expansion boxes and decision- making algorithms that guide the professional in the therapeutic choice.