Like other complex disciplines of dentistry an operator may encounter unwanted or unforeseen circumstances during root canal therapy that can affect the prognosis. These mishaps are collectively termed procedural accidents. However fear of procedural accidents should not deter a practitioner from performing from root canal treatment if proper case selection and competency issues are observed. Endodontic mishaps or procedural accidents are those unfortunate occurrences that happen during treatment, some owing to inattention to detail, others totally unpredictable. This book deals with knowledge of the etiologic factors involved in procedural accidents as it is essential for their prevention.