My dentist didn't ask if we wanted it for our then 2 year old (now 3.5). It was s terrifying experience for him getting a crown with no nitrous (he had weak enamel, despite lots of brushing, still got a cavity). Screaming and fighting the whole time. It took me and 2 nurses to hold him down for the procedure. And getting him to trust a dentist again has been a struggle ever since. The shot they put in your gums numbs your mouth but it doesn't help you to not be afraid and anxious. Nitrous oxide is safe, when they are done, they give oxygen to clear it from your system. Some people feel sick while on it, but that usually means the amount needs adjusted. Try to avoid a large meal right before hand, that can cause some nausea. I recommend letting then give the gas to your little one, the dentist can be scary, let them relieve that anxiety a bit.
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