I've known people who have all four out go into hospital and come out looking like gerbils.
But i've had mine out seperately one at the dentist ( not all dentists do it though) and one in hospital - can't remember why!!
No black eyes, no swelling, no stitches, just numb and can't eat for the rest of the day.
For you they'd probably take the two out on the same side, and then do the other one at a later date so you can still eat.