Failure of inferior alveolar nerve block in endodontics

Analgesia is essential for successful completion of modern dental procedure s. Standard inferior alveolar nerve block (IANB) is the primary method used to achieve mandibular analgesia. Difficulty experienced in obtaining satis factory analgesia after IANB, especially of an acutely inflamed mandibular molar, remains a common clinical problem. Even when a proper technique is e mployed, clinical studies show that IANB fails in approximately 30% to 45% of cases. The reasons for failure are not fully understood. Anatomical cons iderations and abnormal physiological responses in the presence of inflamma tion as explanations for IANB failure are discussed in this paper.