I doubt whip its were the safest thing you were doing, I mean you have to sleep sometime, right? Also, from my understanding nitrous oxide really isn't that good for you. I base this on (very little) research, but I have met quite a few dentists and Grateful Dead followers in my time. They're not all smart, but they all have access to nitrous oxide. It's not even really offered around here anymore, sedation's the big thing.... Although, I will say I tried Nitrous oxide once (while having my wisdom teeth dug out) and I had the scariest hallucination ever-- I was travelling down from my brain, via my brain stem to my heart, and noticed it was beating slower and slower. I was quite sure when I blacked out, I'd be dead (it was oddly realistic, anatomy wise) and ripped the mask off while screaming at the top of my lungs, they just injected me with something to knock me out after that.
It didn't help that my dentist was a dead ringer for the actor on Twin Peaks. Nope, it did not. Which, yay, as apparently my brain needs all the help it can get....
Anna