Orthodontics and paediatric dentistry: nitrous oxide and nasal airway: 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 · Orthodontics and paediatric dentistry: nitrous oxide and nasal airway

Sample item

A 6-year-old with a cold and marked nasal blockage is scheduled for restorations under nitrous oxide-oxygen sedation. Why may sedation fail?

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

The answer and the reasoning

A. The nasal hood needs a patent nasal airway

Nitrous oxide-oxygen is delivered through a nasal hood and the child must breathe through the nose. Nasal obstruction from a cold, enlarged adenoids or allergy reduces the delivery of the gas, so the effect is poor and the appointment is usually postponed.

Option by option

  • A. The nasal hood needs a patent nasal airway (correct)

    Correct. Blocked nasal passages stop the gas from reaching the lungs through the hood.

  • B. The gas can only be given orally by mouthpiece

    Nitrous oxide is given through the nose by a hood, not through a mouthpiece.

  • C. Nasal mucus neutralises the gas chemically

    Mucus does not neutralise nitrous oxide chemically.

  • D. Nitrous oxide is inactive in the presence of a cold

    The agent's pharmacology is unchanged by a cold; delivery is the problem.

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 A, The nasal hood needs a patent nasal airway. Nitrous oxide-oxygen is delivered through a nasal hood and the child must breathe through the nose.

Why is "The gas can only be given orally by mouthpiece" not the answer?

Nitrous oxide is given through the nose by a hood, not through a mouthpiece.

Why is "Nasal mucus neutralises the gas chemically" not the answer?

Mucus does not neutralise nitrous oxide chemically.

Why is "Nitrous oxide is inactive in the presence of a cold" not the answer?

The agent's pharmacology is unchanged by a cold; delivery is the problem.

What concept does this question test?

It tests Orthodontics and paediatric dentistry: nitrous oxide and nasal airway in Dentistry. Nasal obstruction from a cold, enlarged adenoids or allergy reduces the delivery of the gas, so the effect is poor and the appointment is usually postponed.

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 Orthodontics and paediatric dentistry: nitrous oxide and nasal airway?

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.