An Extraction, a Block, and a Drooping Eyelid

Correct answer: C. Facial nerve (CN VII)

• A. CN III supplies levator palpebrae superioris, which OPENS the upper lid. Its paralysis causes PTOSIS — a drooping lid that cannot be raised — the opposite of an inability to close.
• B. The optic nerve is purely SENSORY for vision. It has no motor function and cannot produce weakness of eyelid closure.
• C. CORRECT. The FACIAL NERVE. If the needle passes too far posteriorly and the solution is deposited within the PAROTID GLAND — through which the facial nerve and its branches run — a transient facial nerve palsy results. The temporal and zygomatic branches supply orbicularis oculi, so the patient cannot close the eye; the buccal and marginal mandibular branches produce the drooping mouth corner. It resolves as the anaesthetic wears off, in roughly 1 to 3 hours depending on the agent.
• D. V1 is sensory to the forehead, upper eyelid and cornea. Anaesthetising it would abolish the corneal reflex but would not weaken the muscle that closes the eye.

Note: Immediate management: cover the eye with a patch or have the patient close it manually and apply artificial tears, because the cornea is unprotected without a blink. Reassure the patient, document the event, and inform them it is temporary. The cause is depositing solution too far posteriorly — always contact bone before injecting, and withdraw slightly if you do not.

Correct answer: D. Essentially the entire mandibular division — inferior alveolar, lingual, long buccal, mental, incisive, auriculotemporal and mylohyoid

• A. The mental nerve is a terminal branch of the IAN, so this option is really describing a partial IAN block.
• B. The conventional inferior alveolar nerve block reaches the IAN and usually the lingual nerve, but reliably misses the long buccal.
• C. The maxillary division is anaesthetized by a second-division block via the greater palatine canal or the high tuberosity approach.
• D. CORRECT. The GOW-GATES is a true MANDIBULAR NERVE block. The solution is deposited high, at the neck of the condyle just below the insertion of the lateral pterygoid, where the branches of V3 have not yet fully diverged. It therefore anaesthetizes essentially the whole division — inferior alveolar, lingual, long buccal, mental, incisive, auriculotemporal and mylohyoid. This is why it succeeds where a conventional block fails, including in the presence of accessory innervation via the mylohyoid nerve.

Note: Landmarks: the intertragic notch and the corner of the mouth extraorally; the mesiolingual cusp of the maxillary second molar intraorally, with the patient's mouth WIDE OPEN so the condyle translates forward. Onset is slower (5–7 minutes or more) because of the larger nerve trunk, but the success rate is higher and positive aspiration rates are lower.

Correct answer: C. Infection

• A. TRISMUS is common. The needle traverses the medial pterygoid muscle; haemorrhage into the muscle, or irritation from the solution, produces spasm and restricted opening — typically appearing 1 to 6 days after the injection.
• B. PARAESTHESIA occurs in roughly 1 in 20,000 to 1 in 800,000 blocks, most often affecting the LINGUAL nerve, and is more frequently reported with 4% solutions (articaine, prilocaine). Most cases resolve within 8 weeks.
• C. CORRECT — this is the LEAST likely. INFECTION after an IAN block is rare, because the needle passes through non-contaminated tissue with a sterile single-use needle and the local anaesthetic solution itself is mildly bacteriostatic. It happens only where the needle is contaminated or passes through an infected area.
• D. HAEMATOMA occurs when the pterygoid venous plexus or the inferior alveolar vessels are punctured. It is more visible after a posterior superior alveolar block, but it certainly occurs with the IAN block.

Note: Practical points: aspirate in two planes before injecting, never inject into an area of active infection, and warn patients about post-injection trismus so they do not attribute it to the extraction.

Correct answer: B. Bupivacaine

• A. Articaine 4% with epinephrine gives roughly 60–75 minutes, comparable to lidocaine, with better diffusion through bone.
• B. CORRECT. BUPIVACAINE 0.5% with 1:200,000 epinephrine is the longest-acting dental local anaesthetic, giving roughly 90–180 minutes of pulpal anaesthesia and 4–9 hours of soft-tissue anaesthesia. Its long duration comes from high lipid solubility and high protein binding (about 95%), which anchors it to the sodium channel. It is used for lengthy procedures and, importantly, for POST-OPERATIVE pain control after third molar surgery or periodontal surgery.
• C. Lidocaine 2% with 1:100,000 epinephrine gives roughly 60 minutes of pulpal anaesthesia — the standard workhorse.
• D. Mepivacaine 3% plain gives roughly 20–40 minutes and is useful where a vasoconstrictor is best avoided or a short procedure is planned.

Note: Bupivacaine's prolonged soft-tissue numbness is a real hazard in CHILDREN and in patients with cognitive impairment, who may bite the anaesthetized lip or tongue. Avoid it in those groups.

Correct answer: D. A rash or urticaria

• A. Diarrhoea is an extremely common adverse effect of amoxicillin and reflects disruption of the gut flora, not allergy. Antibiotic-associated diarrhoea, including Clostridioides difficile colitis, is a toxicity issue.
• B. Vomiting is likewise an adverse effect rather than an allergic phenomenon.
• C. Nausea is a common ADVERSE EFFECT, a direct gastrointestinal irritation, not an immune reaction.
• D. CORRECT. A RASH — particularly urticaria, and especially with pruritus, angioedema, wheeze or hypotension — is an IMMUNE-MEDIATED response and supports a true allergy. IgE-mediated reactions typically appear within an hour of the dose. Roughly 90% of patients who report a penicillin allergy are found on testing NOT to be allergic, so a careful history matters enormously.

Note: The distinction is clinically consequential: labelling a patient penicillin-allergic on the basis of childhood nausea pushes them toward clindamycin and broad-spectrum alternatives, which carry higher rates of C. difficile and resistance. Ask specifically: what happened, how soon after the dose, and did it need treatment?