I'm a Canadian currently applying to US dental schools. My brother is a graduate of Michigan's DDS program and from what I hear, there are plenty of us "Canucks" in US dental schools. I think your best bet of finding Canadians are at big private schools (especially in the Northeast) as they're pretty much the only schools that will take non-US students. Oh yeah, an be extra nice to your Canadian classmates b/c we're not only super friendly, we're also paying 1.5x as much as Americans to go to US dental schools (thanks to the woeful exchange on our dollar)!!
Ciao for now,
MDP