I truly think all graduate programs are very competitive. We are on a crisis time and that makes people go back to school, so in this past year the graduate programs turned out to be more competitive than usual.
Loma Linda is famous for accepting foreigners in their graduate programs. But again, that doesn't mean it is easy to get in.
It all depends on what program you are looking at: prostho? ortho? endo?
Plus, it is more common to apply for a masters first, then look for a PhD degree...