It's not realistic in either scenario- doable but not desirable. I've spoken to some above average students(but not gunners!) who plan ahead. They have an interesting take on this. I've heard of moving from a state with no or one dental school to a state with many dental(or other professional schools) that will increase their chances for admission and professional school. We're talking undergrad here, not their family moving of course.
It's not a bad idea. Say you wanted to go out of state for undergrad to a reputable school you have your heart set on. If there is a reasonable reason to move like having no D-school in-state - then do it! It'll cost more, but that bit on undergrad will pay off if you save what 50k+ on dental school.
Still, it's hard. Of the people that declare a "pre-health bio" major. How many of those actually make it? They could change their mind or not do well and now you're paying out of state for what? It's a good idea in theory - say if you went to a very prestigious university that has great back up programs. However, in practice it takes a lot of planning.
Alternatively, you could transfer. That's always a good idea. At least you'll know you WANT to do dentistry as opposed to just winging it freshman year.