I thought twilight sedation (commonly used for dentistry) was still via an IV, no? (edit: apparently Propofol is the most commonly used "twilight" sedation, which I've had quite often during endoscopy/colonoscopy stuff, I highly enjoy the sensation of it!)Sedation dentistry uses the same medications one would take to be put under for an abortion -- medications that run in the Valium family. It's not full surgical anesthesia, that kind of anesthesia requires intubation to prevent aspiration in the lungs during long surgeries. So, they give you some crushed up Valium and about 15 minutes later you're asleep and then they slowly wake you up after.
I'm one of those who would rather be knocked out for any procedure, including dental. There's no way I'd agree to a wisdom tooth removal (I don't have any, luckily won't have to deal with that) without it. I even wish my cleanings were under some sort of sedation. I've thought about asking for gas but I dunno if it'd make me feel like throwing up.