Failure of locoregional anesthesia in dental practice. Review of the literature.

Correct identification of the causes of dental anesthetic failure is essential in order to adopt the required measures for successful anesthesia. A review is made of the factors implicated in locoregional anesthesia failure, such as a bifid inferior alveolar nerve, retromolar foramen associated to accessory innervation, double or accessory mental foramen, the relation between the infiltration technique and bone density, accessory innervation in the case of the mylohyoid nerve and first cervical branches, cross innervation of the incisors, inactivity in the presence of tissue inflammation, inactive anesthetic solutions, an incorrect technique, and subjective perception on the part of particularly anxious patients. The therapeutic options available in the event such problems are encountered in routine clinical practice are commented.