Nitrous oxide is a very safe gas which is mixed with oxygen and inhaled through a small mask over your nose to help you relax and feel calmer during dental visits. Nitrous oxide or "laughing gas" is not always needed for all procedures but may be chosen to be used in certain procedures where a patient feels more anxious. Nitrous oxide is very safe, will not make you fall asleep and you can leave the office shortly after your appointment feeling completely normal.