I don't understand the teeth grills thing either, but if someone wants to do it, as long as they're using their own money, I can't say much about it.
I have heard that these things have the potential to really damage the teeth and mouth -- even the snap-on kind. I know a couple of guys got in a bar fight in my town and one of them had some elaborate gold grills. The other guy punched him in the mouth, and the grills lacerated his lips and he nearly choked on them when they popped off and he almost swallowed them. That's a bad way to lose a lot of money and get hurt in the process.
The newspaper story said the guy's mouth required about 50 stitches. It was torn up.