I had all 4 out at once and the doctor saw an extra tooth somewhere in the roof of my mouth on the x-rays and he wanted to take that out at the same time because he said it would only cause me trouble.
Only problem was that the exact location couldn't be discerned from the xrays they took, so they had to just open the roof of my mouth and look around.
Lousy thing is that after all the cutting (and now scarring) they couldn't find the damn thing, (probably a booger on the film or something

)
They gave me so much IV cocktail (they knocked me out cold for all of it) that I slept for about 26 hours afterward, they had to wheel me to the car and have techs put me in...
Oh well, at least I didnt' feel anything....