Third molar surgery and post-operative pain

Correct answer: C. The lingual nerve

• A. The nerve to mylohyoid branches from the inferior alveolar nerve before it enters the mandibular foramen and runs in the mylohyoid groove. It is chiefly motor and lies well inferior to the surgical field.
• B. The long buccal nerve lies on the BUCCAL aspect, supplying buccal mucosa and gingiva. A lingual approach does not endanger it.
• C. CORRECT. The LINGUAL NERVE runs in the soft tissue immediately against the lingual plate in the third molar region, and in a substantial minority of people it lies AT OR ABOVE the crest of the lingual plate and directly against the periosteum. That anatomic variation is exactly why raising a lingual flap or slipping an elevator lingually puts it at risk. Injury causes numbness or altered sensation of the ipsilateral anterior two-thirds of the tongue, the floor of mouth and the lingual gingiva, and loss of taste on that side.
• D. The inferior alveolar nerve runs WITHIN the mandibular canal, inferior to the roots. It is at risk from root proximity during the extraction itself and from bur or elevator penetration into the canal, but not from elevating the lingual periosteum.

Note: Lingual nerve injury is less common than IAN injury but recovers less well, because the nerve lies in soft tissue with no bony canal to guide regeneration. Protecting it means keeping instruments on bone and avoiding lingual flap retraction where possible.

Correct answer: B. Infection

• A. Haematoma occurs when the needle lacerates a vessel in the pterygomandibular space — the inferior alveolar vessels or the pterygoid venous plexus — and is a well-recognised sequela.
• B. CORRECT. INFECTION after an inferior alveolar nerve block is rare. It requires either a contaminated needle or passage of the needle through an infected field into deep tissue, and with single-use sterile needles and appropriate injection sites both are uncommon. It is not among the routinely-listed complications.
• C. Ecchymosis is the visible bruising that follows a haematoma as blood tracks through tissue planes. It is common enough that patients should be warned about it.
• D. Trismus is one of the commonest complications, arising from needle trauma or haemorrhage into the medial pterygoid muscle, or from an irritant solution. It presents as progressively limited opening over the days following the injection.

Note: Other recognised IANB complications: transient facial nerve palsy from depositing into the parotid when the needle passes too far posteriorly, and paraesthesia, which is more frequent with 4 percent solutions such as articaine and prilocaine.

Correct answer: D. Ibuprofen combined with acetaminophen

• A. Aspirin is irreversibly antiplatelet for the life of the platelet, roughly 7 to 10 days, which is unhelpful after a surgical extraction, and it carries Reye syndrome risk in younger patients.
• B. An opioid alone gives poorer analgesia for inflammatory dental pain than an NSAID does, while adding nausea, constipation, sedation and dependence risk. The 2024 ADA guideline recommends against opioids as first-line for acute dental pain in adolescents and adults.
• C. Acetaminophen alone is reasonable where NSAIDs are contraindicated, but it lacks the peripheral anti-inflammatory action that surgical pain calls for.
• D. CORRECT. The combination of an NSAID with acetaminophen is now the recommended first-line regimen for acute post-surgical dental pain, and it OUTPERFORMS opioid-containing combinations in head-to-head trials of third molar surgery. The two drugs act by different mechanisms — ibuprofen inhibits peripheral prostaglandin synthesis at the site of inflammation, acetaminophen acts centrally — so the effect is additive without additive toxicity.

Note: Staggering the two drugs so that one is peaking while the other troughs gives smoother coverage than taking both together.