Oral and maxillofacial surgery: anaesthesia in infection: practice question

A Dentistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Dentistry · Oral and maxillofacial surgery: anaesthesia in infection

Sample item

A local anaesthetic block fails in a patient with a spreading acute dental abscess. What explains this?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Acidic tissue pH lowers the amount of non-ionised drug that enters the nerve

Local anaesthetics are weak bases, and inflammation lowers tissue pH, increasing the ionised fraction that cannot cross the nerve membrane. Regional blocks away from the infected area help.

Option by option

  • A. Lack of sodium channels

    Sodium channels are present and are the drug's target.

  • B. Acidic tissue pH lowers the amount of non-ionised drug that enters the nerve (correct)

    Correct. Acidic inflamed tissue reduces the free base available.

  • C. Increased protein binding in blood

    Protein binding is not the main explanation.

  • D. Excess alkalinity in tissue

    Infected tissue is acidic, not alkaline.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is B, Acidic tissue pH lowers the amount of non-ionised drug that enters the nerve. Local anaesthetics are weak bases, and inflammation lowers tissue pH, increasing the ionised fraction that cannot cross the nerve membrane.

Why is "Lack of sodium channels" not the answer?

Sodium channels are present and are the drug's target.

Why is "Increased protein binding in blood" not the answer?

Protein binding is not the main explanation.

Why is "Excess alkalinity in tissue" not the answer?

Infected tissue is acidic, not alkaline.

What concept does this question test?

It tests Oral and maxillofacial surgery: anaesthesia in infection in Dentistry. Regional blocks away from the infected area help.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Oral and maxillofacial surgery: anaesthesia in infection?

Learn the dental formula, eruption ages and tooth structure once, as tables. Then use the flashcards and the other Dentistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.