Chest Pain During the Appointment

Correct answer: B. Inhibits HMG-CoA reductase

• A. Incorrect. That is ezetimibe, which blocks the NPC1L1 sterol transporter in the intestinal brush border.
• B. Correct. Statins competitively inhibit HMG-CoA reductase, the rate-limiting enzyme of hepatic cholesterol synthesis. Falling intracellular cholesterol upregulates hepatic LDL receptors, which clears LDL from the circulation.
• C. Incorrect. Lipoprotein lipase activation is the mechanism of the fibrates such as gemfibrozil and fenofibrate, which are used primarily to lower triglycerides.
• D. Incorrect. That describes the bile acid sequestrants — cholestyramine, colesevelam — which interrupt enterohepatic recirculation of bile acids.

Correct answer: A. Releases nitric oxide, which activates guanylyl cyclase and raises cGMP

• A. Correct. Nitroglycerin is metabolized to nitric oxide, which activates soluble guanylyl cyclase. The resulting rise in cGMP dephosphorylates myosin light chains and relaxes vascular smooth muscle. Venodilation predominates, reducing preload and therefore myocardial oxygen demand.
• B. Incorrect. COX inhibition is the mechanism of the aspirin she already takes. Aspirin is critical in acute coronary syndrome for its antiplatelet effect, but that is not how nitroglycerin works.
• C. Incorrect. Calcium channel blockade describes amlodipine, nifedipine, and diltiazem. These also treat angina, but through a different pathway.
• D. Incorrect. Beta-1 stimulation with rising cAMP describes dobutamine or epinephrine at the cardiac receptor. It increases oxygen demand, the opposite of what is needed in angina.

Note: Contraindication worth knowing: nitroglycerin must not be given within 24–48 hours of a phosphodiesterase-5 inhibitor such as sildenafil or tadalafil. The combination causes profound, refractory hypotension.

Correct answer: C. It blocks beta-1, beta-2, and alpha-1 receptors, lowering heart rate, contractility, and afterload

• A. Incorrect. Selective beta-2 blockade has no therapeutic use and would provoke bronchospasm. Beta-2 agonism, not antagonism, is what albuterol does.
• B. Incorrect. Angiotensin II receptor blockade describes losartan and valsartan — the drugs with the -sartan suffix.
• C. Correct. Carvedilol is a third-generation, non-selective beta blocker with additional alpha-1 antagonism. Beta blockade lowers heart rate and contractility, reducing oxygen demand, while alpha-1 blockade produces peripheral vasodilation that lowers afterload.
• D. Incorrect. ACE inhibition describes lisinopril and enalapril — the drugs with the -pril suffix.

Note: Dental relevance of non-selective beta blockade: epinephrine in local anesthetic can produce unopposed alpha-mediated vasoconstriction with a rise in blood pressure and reflex bradycardia. Limit the dose, aspirate carefully, and monitor.

Correct answer: B. Simvastatin

• A. Incorrect. Nitroglycerin is used acutely and intermittently and has no documented effect on pulpal tissue.
• B. Correct. Several retrospective imaging studies have reported an association between long-term statin use and reduced pulp chamber volume, attributed to the pleiotropic effects of statins on osteoblastic and odontoblastic differentiation, including BMP-2 upregulation.
• C. Incorrect. Low-dose aspirin affects platelet function, not dentinogenesis.
• D. Incorrect. Beta blockers have no reported association with pulpal calcification.

Note: Flagged — this is a recognized board answer but the evidence is limited and consists mainly of retrospective radiographic studies. The far more common causes of pulp canal obliteration remain age, trauma, attrition, deep restorations, and orthodontic movement. Keep those first in your clinical differential.