I will be attending UMDNJ, I love the faculty there and the school itself is top notch. As far as Newark is concerned, if safety is an issue, if you decide to live in the campus housing, that building is connected to the dental school by a tunnel that can only be accessed through guarded areas, so you don't even have to go along the street if you choose not to (this is also good to use in bad weather). If you are commuting in, UMDNJ has guarded parking garages. I spent two weeks there for an internship and I went through the surrounding areas (1 block surrounding the school) and no one ever bothered me. As long as you mind your own business and don't go out alone at night on the street, I don't think you will have any problems.
The city of Newark provides UMDNJ with a very large and diverse patient base, and I am pretty excited about that.
Congrats on getting in!