I think for Dental school there really isn't any school of last resort that anyone would be able to get into. The people at both Pitt and Columbia said that this year and last year, dental school has overcome med in how competitive it is to get accepted somewhere.
If you're looking at straight numbers, which isn't necessarily the best way to judge it, Meharry has lower scores, but their admissions focus isn't on that as much as it is giving people opportunities to give back to their community, and helping under represented groups be a larger part of the dental community and that kind of thing.