Is it "urban legend" or truth, that dented cans on store shelves are "dangerous," and should be avoided?

My wonderful mother told me always examine them, to make sure they weren’t dented, because if I ate the contents, I’d get very sick and die.

I always thought that if they were PUNCTURED, that there was a serious health risk, but merely being dented, in and of itself, was nothing about which to be concerned.

So what’s the straight stuff on this?