This is a procedure that can be used in the office with a very fearful child. It utilizes a gas called nitrous oxide (laughing gas) that is introduced through the nose. Nitrous oxide has no side effect. The gas has a minor sweet smell. It is quickly absorbed through the lungs and it quickly leaves their system after the procedure. It changes the awareness of your child and decreases their motor function.
In other words your child relaxes but he/she is still awake and can interact with their surroundings. The procedure can be reversed at any moment which makes it safe. The experience of your child is a pleasant one with some memories of the appointment but no details.