Sores after surgery- common???

I've read a lot on here and the j-pouch forum about people getting sores by their stomas or waking up after surgery with a mouthful of ulcers and whatnot... Is this very common??? What is it from?? I get mouth sores quite frequently as it is (I have two in my mouth at the moment) and wonder if this could be a problem for me if I got surgery?

Do you think sores by the stoma could be prevented by taking any certain measures?? It sounds like some people have had some pretty severe ones which sounds not only scary, but painful!!