What is the most prompt relief method for a patient suffering from angina in the dental chair?

Sublingual administration of glyceryl bi-nitrate is the most effective and prompt relief method for a patient experiencing angina in the dental chair. Glyceryl bi-nitrate, commonly known as nitroglycerin, works by quickly dilating blood vessels, which helps to reduce the workload on the heart by improving blood flow and oxygen supply to cardiac tissues. When administered sublingually, it enters the bloodstream rapidly, leading to near-instantaneous relief of angina symptoms.

The other options may provide relief or are relevant in other circumstances, but they are not the first-line choice for immediate angina relief. For example, oral administration of short-acting barbiturates does not provide rapid relief and is not specifically indicated for angina management. Subcutaneous administration of morphine sulphate is more frequently used in severe pain or myocardial infarction cases and is not the immediate remedy for angina. Lastly, while epinephrine can be useful in certain emergency situations, it is not indicated for treating angina and can actually exacerbate the condition by increasing heart rate and oxygen demand.