It's all about how good you get at dentistry, how much knowledge of the field and business you have, and overall getting the most out of dental school as you can. Most likely, if you do not go above and beyond to educate yourself about dental economics and the future of the field, you will end up in a cooperate setting for life these days.
Sure, if you go to one of the 5 or so prestigious schools you may have some SLIGHT advantages, and may be able to specialize easier if you would like, but it's not a huge advantage.
Now, going to the bottom-barrel schools (about 5-10 of these), you would probably have a tougher time earning a lot. I think you would struggle to escape the cooperate grips going to one of these.