A patient seizes while a crown is being cemented. Afterwards the crown cannot be found, and the patient becomes cyanotic. What is the immediate action?

Correct answer: A. Assess the airway

• A. CORRECT. A missing crown plus cyanosis equals AIRWAY OBSTRUCTION until proven otherwise. Follow ABC: open the airway, look in the oropharynx, suction, and if the obstruction is complete deliver abdominal thrusts or back blows. Cyanosis means the patient is not oxygenating NOW, and nothing else matters until that is resolved.
• B. The seizure has already ended. Giving a benzodiazepine to a cyanotic patient adds respiratory depression to an obstructed airway.
• C. Positioning and oxygen do not move a foreign body. Oxygen cannot reach the lungs past a mechanical obstruction.
• D. Imaging is essential later — to determine whether the crown was aspirated into the bronchial tree or swallowed — but it is a diagnostic step, not a resuscitative one.

Note: This is why a rubber dam, a gauze throat screen or floss ligated to small restorative objects matters. If the item is later found to have been aspirated it must be retrieved bronchoscopically. If swallowed and the patient is stable, a sharp object needs endoscopic removal while a smooth one is usually monitored radiographically until it passes.