Are you originally from Australia yourself? Or your parents? That's wicked.
Umm...I don't think they would ask you any questions that are above and beyond "normal" interview questions. Just be familiar with your own self and your background and you'll do just fine. I don't think many Aborigines make it to US dental schools if you are applying in the US (I assume because Australian dental school is seven years including undergraduate so you'd probably already be in the program) I bet this would give you a distinctive quality. Just relax and have fun with the interview process.
Good luck.
Jessica