Here are some...I know people will blast a few of these for being too forward, but I'm just putting them out there...you don't have to ask them.
What kind of community service opportunities are offered at this school?
What is the patient population like? are the dental procedures generally diverse? If a patient cannot pay for treatment, what happens to them?
If a certain # of procedures are required for graduation and the patients you are given do not require that procedure, how does a student go about finding a patient to do the work on? Does the school assist in finding those patients?
Is there housing near the campus? How expensive is it? Is there student housing?
Can the students come into the school after hours to finish doing work?
What is the Boards Passage rate at this school? What % of your students that want to pursue specialties get into specialty schools?
Will I get to experience oral surgery, endo, perio, or will most of that stuff be taken by specialty residents?
If there was anything about the school that you would like to change, improve, or upgrade, what would it be?