An IAN block has been given and the patient has profound soft-tissue anesthesia (lip and tongue numb), but experiences pain when root canal treatment is initiated on the mandibular first molar. What is the best supplemental technique?

When a patient has profound soft-tissue anesthesia (confirming a successful IAN block) but still experiences pain during endodontic treatment on the mandibular first molar, the cause is typically accessory innervation (e.g., mylohyoid nerve) or the inflammatory state of the pulp lowering the pain threshold. The most effective supplemental technique in this scenario is a buccal infiltration with 4% articaine. Articaine has superior diffusion through bone cortex compared to other local anesthetics due to its thiophene ring, making it effective for mandibular buccal infiltrations. This approach has strong clinical evidence for success.