MFDS Human Disease and Pharmacology

Question 1

A patient with a prosthetic heart valve presents for a dental extraction. According to current NICE guidelines (2016 update), what antibiotic prophylaxis is recommended?

Accepted Answer

Antibiotic prophylaxis is NOT routinely recommended by NICE for dental procedures, even in patients with prosthetic heart valves

Answer

NICE Clinical Guideline CG64 (updated 2016) recommends that antibiotic prophylaxis against infective endocarditis should NOT be routinely offered for dental procedures in the UK, including for patients with prosthetic heart valves. This differs from American Heart Association guidelines which still recommend prophylaxis for high-risk patients. The NICE position emphasises that the evidence does not show a clear link between dental procedures and infective endocarditis development.

Question 2

A diabetic patient taking metformin presents for dental treatment. Their HbA1c is 75 mmol/mol (9.0%). What is the clinical significance of this result?

Accepted Answer

The diabetes is poorly controlled (target <48 mmol/mol), indicating increased risk of delayed healing, infection, and the need for medical liaison before elective surgical procedures

Answer

An HbA1c of 75 mmol/mol (9.0%) indicates poor glycaemic control. The NICE target for type 2 diabetes is generally 48 mmol/mol (6.5%) or 53 mmol/mol (7.0%). Poor control increases the risk of impaired wound healing, susceptibility to infection (including periodontal disease progression), dry mouth, candidiasis, and delayed recovery from surgical procedures. Medical liaison is advisable before elective invasive dental treatment.

Question 3

What is the mechanism of action of adrenaline (epinephrine) when used in a dental local anaesthetic cartridge?

Accepted Answer

It is a sympathomimetic amine that causes local vasoconstriction via alpha-1 adrenergic receptors, reducing local anaesthetic absorption and prolonging the duration and depth of anaesthesia

Answer

Adrenaline acts on alpha-1 adrenergic receptors in blood vessel smooth muscle, causing vasoconstriction at the injection site. This reduces blood flow, which slows systemic absorption of the local anaesthetic agent, prolongs its duration of action, increases the depth of anaesthesia, reduces bleeding at the surgical site, and lowers the risk of systemic toxicity by reducing peak plasma levels. The typical concentration in dental cartridges is 1:80,000.

Question 4

A patient presents for emergency dental treatment and reports taking clopidogrel and aspirin (dual antiplatelet therapy) following coronary stent insertion six months ago. How should this be managed?

Accepted Answer

Do NOT stop either drug — perform the extraction with local haemostatic measures such as suturing, oxidised cellulose, and tranexamic acid mouthwash

Answer

Current guidelines recommend NOT stopping dual antiplatelet therapy for dental extractions due to the risk of stent thrombosis, which carries a mortality rate of up to 40%. Local haemostatic measures are sufficient to manage post-extraction bleeding: suturing, oxidised cellulose (Surgicel) or collagen sponge in the socket, and tranexamic acid 5% mouthwash (held for 2 minutes, four times daily for 2 days). The bleeding risk from dental procedures on antiplatelet therapy is low and manageable.

Question 5

What is the initial emergency management of anaphylaxis in the dental surgery according to the UK Resuscitation Council guidelines?

Accepted Answer

Administer intramuscular adrenaline 1:1000 (500 micrograms for an adult) into the anterolateral thigh, call 999, and position the patient supine with legs elevated

Answer

The UK Resuscitation Council guidelines for anaphylaxis in the dental practice: 1) Call for help and dial 999; 2) Administer IM adrenaline 1:1000 (500 mcg/0.5 mL for adults) into the anterolateral thigh — repeat at 5-minute intervals if no improvement; 3) Position supine with legs elevated (sitting up if breathing difficulty); 4) High-flow oxygen 15 L/min; 5) IV access and fluids if trained; 6) Chlorphenamine 10 mg IM and hydrocortisone 200 mg IM as second-line treatments.

MFDS Part 1 Practice Test

MFDS Part 1 Practice Test

MFDS Human Disease and Pharmacology