An inferior alveolar nerve block has been given, adequate time has elapsed, and the patient reports no numbness at all. What is the most appropriate next step?

Correct answer: A. Repeat the injection at a site more superior and slightly more posterior

• A. CORRECT. Total failure of an IAN block usually means the solution was deposited BELOW the mandibular foramen, which is the commonest technical error. Re-injecting HIGHER (and slightly posterior) places the solution above the foramen, where it can diffuse down onto the nerve as it enters the canal. This is also the rationale of the Gow-Gates and Vazirani-Akinosi techniques, both of which deposit at a higher level.
• B. Waiting alone will not help if the solution was never placed within diffusion distance of the nerve. Onset should occur within about 5 minutes; beyond 10–15 minutes, re-inject.
• C. Depositing lower moves further away from the foramen and makes success less likely, not more.
• D. Repeating the same technique at the same landmarks simply reproduces the same error and the same failure.

Note: Distinguish the two failure patterns. NO numbness anywhere means a technique/deposition problem — re-inject higher. Numb lip and tongue but a still-sensitive TOOTH means accessory innervation or an inflamed pulp — supplement with buccal articaine infiltration, intraligamentary, intraosseous or intrapulpal anesthesia.