Which complication is LEAST likely to follow a local anesthetic injection?

Correct answer: D. Infection

• A. ❌ Paresthesia is uncommon but well documented, especially involving the lingual nerve after an IAN block.
• B. ❌ Trismus follows medial pterygoid trauma or hemorrhage and is a well-recognized complication of the inferior alveolar block.
• C. ❌ Hematoma is comparatively common, particularly after a posterior superior alveolar block where the pterygoid venous plexus may be entered.
• D. ✅ CORRECT — INFECTION following local anesthetic injection is rare. Single-use sterile needles and cartridges, plus the antibacterial properties of the anesthetic solution itself, make needle-track infection an uncommon event.

Note: Frequency ranking, roughly: trismus and pain on injection are common; hematoma and paraesthesia are occasional; needle fracture and infection are rare.