Although sevoflurane sedation have the advantage of the reduction of anxiety and pain relief, difficult airway is attributed to increased agitation, tachycardia, desaturation, ventilation difficulty, sedation failure. In the sedation for dental treatment, we should pay more attention to the airway management because dental procedures take place in the mouth of airway unlike any other area. The layngeal mask airway (LMA) has become commonly used device for airway management during anesthesia for relatively short procedures, such as minor oral surgery and dental procedures. It can be inserted without use of a larygoscope and muscle relexants, and insertion is easy to achieve and generally takes less time than endotracheal intubation. The LMA is an excellent barrier against aspiration of saliva, blood within the surgical field but should not be used in patients at risk of aspiration In this study, we reported that after a failure of airway management in inhalation sedation, we performed the short-emergency dental treatment successfully, using a laryngeal mask.