Pharmacology in Dentistry Flashcards

What is the role of benzocaine topical anaesthetic in dental practice?

Answer: Used as a topical surface anaesthetic applied to mucosa before injection to reduce needle discomfort — works by superficial mucosal penetration only

Benzocaine (and lidocaine) gels/sprays are applied topically to dry oral mucosa before injection to anaesthetise the superficial nerve endings, reducing the discomfort of needle insertion.

What is the significance of epinephrine (adrenaline) concentration in LA cartridges for cardiac patients?

Answer: Use the lowest effective concentration (1:100,000 or 1:200,000); avoid 1:80,000; limit to 2–3 cartridges maximum; use slow aspiration and injection technique to minimise cardiovascular effects

In cardiac patients (stable angina, treated hypertension, controlled arrhythmia), LA with adrenaline can be used cautiously. Limit dose (maximum 2–3 cartridges), use 1:100,000 or 1:200,000, aspirate carefully, and inject slowly to avoid intravascular injection.

What is 'MRONJ' and which drugs are most commonly implicated?

Answer: Medication-Related Osteonecrosis of the Jaw — exposed necrotic jaw bone for >8 weeks without healing; most commonly caused by IV bisphosphonates (zolendronic acid) for bone metastases, and denosumab

MRONJ is exposed, necrotic jaw bone failing to heal in a patient on antiresorptive (bisphosphonates, denosumab) or antiangiogenic agents. IV bisphosphonates (zoledronic acid) for malignancy carry the highest risk; oral bisphosphonates for osteoporosis carry a lower risk.

Which drug interaction is relevant when prescribing metronidazole to a patient on warfarin?

Answer: Metronidazole inhibits CYP2C9 increasing warfarin levels and INR — bleeding risk increases significantly; warfarin dose reduction and INR monitoring required

Metronidazole significantly inhibits CYP2C9 (the enzyme primarily responsible for S-warfarin metabolism), raising warfarin plasma levels and INR substantially. This combination requires enhanced INR monitoring and likely warfarin dose reduction.

What is the pharmacological basis of conscious sedation using midazolam in dentistry?

Answer: Midazolam enhances GABA-A receptor activity, increasing chloride ion influx and reducing neuronal excitability — producing anxiolysis, sedation, amnesia, and muscle relaxation while maintaining consciousness

Midazolam is a short-acting benzodiazepine that binds to GABA-A receptors, enhancing the inhibitory effect of GABA. This produces dose-dependent CNS depression: anxiolysis, sedation, anterograde amnesia, and muscle relaxation.