You can probably skip one of a five year old's twice-annual dental checkups, given that they've still got baby teeth and likely to just get a clean. More of a choice than one might think, especially if you've got a kid who truly loves ballet.
Whatever the choice made, it sucks to have to make it.
That's simple: dentist. Of course the 5 year old will definitely not agree with that choice but health comes first no matter what.