Nitrous Oxide Sedation — NDEB AFK MCQ

Correct answer: A — 70%

The maximum concentration of nitrous oxide (N₂O) for conscious sedation in dentistry is 70%, with a minimum of 30% oxygen always delivered (fail-safe mechanism). Most patients achieve adequate sedation at 30-50% N₂O. Concentrations above 50% may produce deep sedation or loss of consciousness. Modern dental sedation units have a built-in oxygen fail-safe that prevents delivery of less than 30% oxygen. Scavenging systems are mandatory.

Reference: Malamed – Sedation: A Guide to Patient Management, 6th ed., 2018