I think chewing gum too often can actually be bad, it overdevelops the chewing musculature and you chew with too much force. The ingredients in gum are usually bad too, like real sugars or artificial sweeteners like aspartame, as well as food coloring s. If you could get a natural one that might be good.
I know that chewing on crispy crunch things like biting into apples is supposed to be good for the teeth and gums, that resistance work tightens the teeth in their sockets or something like that.