I would suggest setting up a visit to discuss how you can strengthen your application for the next cycle (if you have a preferred school, especially if one is your state school). This helps demonstrate your commitment to improving your application and it can also provide an opportunity to update the school on any additional EC's, etc you may have undertaken/achieved. This could also improve your chances for this cycle. How much is anyones guess.
Once you have a meeting set up you then want to be careful not to appear as though you are trying to "force" your way off the waitlist. Really approach the meeting with the mindset, and message, that you just want to do whatever it takes in the coming few months to get into their dental school. Ask them for a brutally honest critical analysis of what your deficiencies were and also what your strengths were.
Something else that would useful would be to get an idea of what "type" of applicant they view you as. Meaning, do they view you simply as a candidate with good grades, good DAT scores and standard EC's? or do you have some life experience or career plan which puts you into a different category of applicant, ie. someone that might work in underserved areas, someone with artistic skills, etc. Most of all be sincere and honest (telling you something I'm sure you already know there). Remember, classes typically are composed of a range of different types of applicants. Just find out where they think you might fit in the/a class they have constructed. Also, hurry up and set up the meeting