I did the Environmental Health and Toxicology branch, just for the sake of trying to take more sciences since a lot of the PH stuff doesn't necessarily fall under the sciences as defined by dental schools. To be honest, if I had it to do over again, I would have just taken as many post-bac science classes as I could handle. I ran into the issue a bit that the MPH doesn't have a lot of street cred with the dental schools, as the programs (as a general rule) aren't too terribly difficult.
I would say that what set my application apart is retaking the DAT--19 first go around with a retake of 20. Additionally, I scored a 25 on the reading comprehension section, which substantially helped my application. My undergrad GPA was far from stellar at around 3.1, but I worked hard during the PH and swung a 3.84. I think I mentioned it in a different thread, but the big thing to shoot for is to get the GPA/DAT scores as high as you possible can (I know, much easier said than done). Once you do that, you kind of get placed in the right 'pile', if you will. Getting in the right pile will also help score you an interview, and then all of your volunteer, extracurriculars, work, etc. can really help you shine.
Tried to touch on as much as possible, but let me know if I missed something you wanted to know
