So what you're saying is, the moment you fall asleep you basically wake up 3 minutes later, not knowing what happened or how long the void of time you were asleep was? Thanks for answering, also I'm trying not to derail the topic.
Eh, I had a few teeth removed before I got my braces on and they gave me an IV instead of gas for some reason. Count yourself lucky they're not sticking a huge needle in your arm with a little bit of local anesthetic. :<
The mask is nothing. You just breath normally, you're asleep in seconds. The worst part will be a few hours after you wake up, but the pain gradually comes back, so it's not overwhelming. More irritating, really. Don't sweat it too bad.