A 7-year-old girl visited the Samsung Medical Center emergency room for primary tooth aspiration during primary tooth extraction under conscious sedation with N2O. The patient showed no signs of respiratory complications.Chest radiography and CT revealed a tooth in the right bronchi. Foreign body removal using rigid bronchoscopy was performed on the day of aspiration. With close monitoring of the airway in the pediatric ICU, extubation was performed the next day, and the patient was discharged the same day. The primary objective of this case report was to highlight the potential risk of aspiration associated with the use of N2O gas for conscious sedation.