Clinical pearls

Articaine 4% with 1:100,000 adrenaline may give higher anaesthetic success than lidocaine 2% in posterior teeth with irreversible pulpitis (low-quality evidence). Consider it when lidocaine has failed.

Metronidazole + alcohol = disulfiram-like reaction. Always warn patients to avoid alcohol during treatment and for at least 48 hours after stopping (SDCEP).

Lidocaine 2% with 1:80,000 adrenaline: the mg/kg limit is 7 mg/kg (absolute anaesthetic ceiling 500 mg), but for a healthy adult the TOTAL ADRENALINE CEILING of 200 mcg binds first. At 27.5 mcg per 2.2 mL cartridge this allows approximately 7.2 cartridges (~316 mg lidocaine). Lidocaine plain (no vasoconstrictor): BNF maximum 200 mg — approximately 4.5 cartridges (198 mg) in an adult. Always calculate both ceilings and use whichever gives the lower cartridge count.

Phenoxymethylpenicillin 500 mg QDS is first choice for dental infections needing antibiotics; amoxicillin 500 mg TDS if compliance is a concern. Metronidazole 400 mg TDS is appropriate in penicillin allergy. Usually 3-5 days; review at 3 days.

Ibuprofen 400 mg is more effective than paracetamol 1 g after third molar surgery. Ibuprofen 400 mg plus paracetamol 1 g together shows encouraging results (moderate-quality evidence).

Miconazole oral gel interacts with warfarin — can cause INR to spike dangerously. Use nystatin suspension instead.

Adrenaline in LA is not contraindicated in controlled hypertension. Limit to 2 cartridges and aspirate. Pain-induced adrenaline release is far more dangerous.

Chlorhexidine mouthwash 0.2% (10 ml for 1 minute twice daily) produces a large reduction in plaque. Warn patients about brown staining and taste disturbance; both are reversible.

Penicillin allergy (dental abscess): metronidazole is the SDCEP first-line choice. Macrolides are second-line only, for severe infection or no response to a full first-line course after review: clarithromycin 500 mg twice daily for 5 days. Do not prescribe clarithromycin in pregnancy or breastfeeding, or to patients taking warfarin or a statin. Erythromycin is not an SDCEP dental option.

Codeine is a prodrug metabolised by CYP2D6 to morphine. Up to 7% of Caucasians lack this enzyme, so codeine will not give adequate analgesia in these patients.

Prilocaine 3% with felypressin is preferred over lidocaine + adrenaline in patients with severe uncontrolled cardiac arrhythmias.

Articaine 4% with 1:100,000 adrenaline: 7 mg/kg (absolute ceiling 500 mg). At 88 mg per 2.2 mL cartridge, 7 mg/kg × 70 kg = 490 mg ÷ 88 mg/cart ≈ 5.5 cartridges for a healthy 70 kg adult. (The adrenaline ceiling of 200 mcg does not bind first: 5.5 carts × 22 mcg/cart ≈ 121 mcg, safely below 200 mcg.) Always calculate the anaesthetic-mg limit AND the adrenaline ceiling — use whichever yields fewer cartridges.