Definitely go with the oral surgeon and the IV.
I did that and STILL woke up in the middle of it all. I had the biggest wisdoms this guy had ever seen in 20 yrs of practice (i also have this strange dougle innervation thing that about 2% of people have which makes me very difficult to numb there). Anyway, it was awful like that. I cant even IMAGINE what it would have been like with only the nitrous. holy shit i would have killed a hygenist i think