This is neat, I like this.
I mean, I think this exact request is kind of gauche and not for me, but it's nice to see people taking advantage of the medium to do something interesting and expressive. There's a ton of opportunity for this kind of thing, given we're making one-of-a-kind products tailored to the individual already, so why not?
People already choose materials based in part on appearance and as a personal expression; choosing something natural-looking is one expression, picking a gold crown in part for its look is another. A turquoise tooth is no different than these classic options, just unusual. Why shouldn't we explore the much wider range of appearances and designs that are now available to us with modern materials and processes?