Like @cacajuate said, didactic is a more general term that encompasses the art of teaching itself. It's not a specific type of education.
It's PBL vs Traditions vs other different methods schools use (all schools are different to an extent, many use combinations of PBL/Lecture)
I personally believe that a good mix of each would be more beneficial for me. People learn differently, too. So it really depends on you as a person.
A friend I have really hates PBL and he's in a school that doesn't have any lectures. However, he still really likes the school and thinks he's getting the education he needs even though he's teaching himself everything. He expected that going in and thinks he would be doing that at any other traditional school anyways.
A lot of it is teaching yourself and making sure you're going to become a great dentist.
So if you have a choice... I'd just go to the cheapest school. The education is not worth the difference in price.