Nitrous oxide-oxygen 

Inhalation sedation also is known as nitrous oxide-oxygen sedation (N2O-O2) is a state of conscious sedation. Where the patient is awake, relaxed, responsive to commands, and having intact protective reflexes. The sedation method is a good alternative for patients who have low pain reaction tolerance and anxiety before dental treatment. When the gases are inhaled through a nosepiece the effects are felt immediately. Nitrous oxide is characterized by easy onset, minimal side effects, and rapid recovery.