Nitrous Oxide or "laughing gas" is a safe and effective tool to manage dental anxiety. Nitrous Oxide decreases tension that enhances the perception of pain and makes for a more relaxed dental visit.
It is most commonly used on kids to minimize the squirming than children do anytime they have to hold still for a long time.
Since Nitrous Oxide is a gas the patient breathes in through a nasal hood, it enters the body and takes effect within 3 minutes and leaves almost as quickly. This is ideal for dental procedures because patients are able to drive themselves within minutes of leaving the dental chair, unlike other forms of sedation where the patient is sedated to the point of unconsciousness.
One common misconception with "laughing gas" is that it replaces local anesthetic. This may be because a patient on Nitrous Oxide feels the local anesthetic injection less, so they may not even recognize that they got a shot. But, whatever the case, most dental work requires local anesthetic. Nitrous Oxide just helps ease the discomfort of receiving the injection.
In my experience, I have found that while Nitrous Oxide is not for everyone, it really helps others.