Well, you're right--this hypothetical would be more financially sound for OP, especially since it is Alabama. But I would never put all of my eggs in one basket like that. I guess what I'm saying is that a good financial decision in this situation is one that accounts for the most significant uncertainties. Admission to a single school is a huge uncertainty in this sense, even for applicants who seem overqualified.
BTW,
Another point to be made in this discussion thread is that important life decisions can be endlessly complex financial decisions, yet they also have even more to them. Sure, it is wise to prioritize finance, but as someone who is not going into this profession for the money, I personally would weigh factors such as the quality of the education and my short-term happiness more than other people might. If I get depressed from spending the rest of my 20s in a school I don't like in a crappy town, I might (1) have trouble finding a wife, (2) have a weak network of colleagues centered in an area where I don't want to practice, and (3) lose some of my professional drive. And, the funny thing is, these are all also financial effects, which could potentially dwarf the initial saving! I had a miserable time in undergrad because I ignored these other variables in favor of the school's ranking and alumni earning power, and I don't know if I'll ever fully recover from those four years of being surrounded by sociopaths. I literally can't afford to repeat another four years of unhappiness like that. Everyone is in a unique situation, but I totally think choosing a private school CAN be justified. Granted, I think the cost of even the cheapest dental school is obscene, and something needs to be done about these annual tuition hikes.