Alright, this has been a really long forum thread. And I admit I'm a bit tired and may not remember all the facts completely straight. But in either case I cannot believe that I have to say this:
You should NOT use a grinder to remove 37 year old gum from a 4 year old. That is completely inappropriate and dangerous to the 4 year old.
Now if I have that backwards, you also should not use a grinder to remove 4 year old gum from a 37 year old. But at least here you have a shot at it working out okay if you plan ahead.
Maybe just make sure no onions or hot peppers or something, if you have a choice. Now if your only choices are a grinder or like a Philly Cheesesteak or maybe a jalapeno bagel or something, then give the grinder a try, I guess.
But I still think a grinder with a 4 year old's yet undeveloped digestive system is just asking for trouble.
OK...gotta get some sleep now. I'll check tomorrow night to see how it turned out. Good luck.