| I always get nitrus oxide at the dentist. Because I hate and fear the dentist, but I fear not going to the dentist and having bad teeth more.
I've never had wisdom teeth pulled, but as for the nitrus oxide, I wasn't very loopy at all afterwards. It calmed me down a lot and it seems to have an effect that makes time pass faster. So I felt like I had only been sitting in the chair for like, 15 minutes when it had been an hour, which was cool.
They put the mask ( for the gas) on me at first before the dentist even came around so you're nice and calm if you get freaked out for the needles (to freeze your mouth).
Nitrus Oxide is great O_o. Nothing to fear there.
As for the Oxycontin they may give you afterwards, I've recieved that too from the dentist. They never give it to you in quantities where you could possibly become dependent on it. | 
