From what I have gathered, there is very little in the way of housing for dental students at NYU. I think you can live in the dorm (but not if you are married, have a partner), and I think the dorm is still pretty expensive. I think there is a detailed discussion of this from a few years back on SDN. Just do a search with NYU and Housing in the title.
I am planning on finding my own housing (scary idea, I know). But I have to, because I am married. I spoke with a few students while at my interview who said they had no problem getting apartments on their own (without a broker) a few weeks before they moved (with the help of newspaper clippings, the Village Voice).
Also, I recently bought a really helpful book that you may want to consider if thinking about moving to NYC. It is by Belden Merims and called "Newcomers Handbook for moving to New York City." Got it on amazon for $10 or so.
Also, Ellen R. Shapiro's book "Relocating to New YOrk City and Surrounding Areas." is also helpful and available on amazon.
I know I am kind of a nerd for getting these books, but what can I say, I'm freakin excited about moving to NYC!!!!