You administer an inferior alveolar nerve block and the patient does not achieve profound anaesthesia. On re-injection, where should the needle be redirected?

Correct answer: D. More superior and slightly more posterior

• A. Going medial risks entering the pterygomandibular raphe or the medial pterygoid muscle, producing trismus rather than anaesthesia.
• B. Anterior and inferior is the direction of the ORIGINAL error — going further that way guarantees another failure.
• C. Repeating the identical injection reproduces the identical failure. Something in the technique must change.
• D. CORRECT. The commonest reason for IAN block failure is depositing solution TOO LOW (below the mandibular foramen) and TOO FAR ANTERIOR. Redirecting HIGHER and slightly more POSTERIOR places the solution in the pterygomandibular space above the foramen, where it can bathe the nerve before it enters bone. Raising the injection height also captures accessory innervation, which is why the Gow-Gates and Vazirani-Akinosi techniques deposit high on the ramus.

Note: If a second correctly placed block still fails, consider accessory mylohyoid innervation, cross-innervation, or an inflamed/acidic field, and consider a buccal infiltration with articaine or an intraosseous technique.