When a root canal treatment fails, the clinician faces the challenge of deciding whether to retreat the tooth or to extract it. This book provides a systematic approach to reintervention in endodontics, addressing both nonsurgical retreatment and surgical endodontics. The authors begin with a discussion of the biologic and technical reasons for failure and then offer step-by-step clinical protocols for reintervention. The text covers the removal of posts and cores, separated instruments, and carrier-based obturators; the management of transportation, ledges, perforations, and resorption; and surgical techniques such as apicoectomy and intentional replantation. Case studies and clinical photographs illustrate each procedure from diagnosis through follow-up. Designed as a clinical guide, this book provides practitioners with the knowledge and techniques they need to manage failed endodontic cases predictably and conservatively.