Those who get interviews are individuals who the dental school recognizes as potential dental students. The interview process is there to make sure those who are joining their school have adequate social skills to be a dentist. During the interviews your performance allows dental schools the ability to gauge your communication skills with your future patients. Based on your performance, dental schools can gauge your ability to interact with others, your effectiveness in communication, your listening skills, ability to establish relationships with trust and confidence, and management.
Make sure you suit up! The idea is that the nicer you look, the more time it took you to prepare yourself, which can be directly correlated to how much you want a position at the dental school. Bring copies of resumes, business cards, and anything else you may have that has not been expressed in your application. Things like dental models or a portfolio are great to bring along!