MS in biology or biomedical sciences is a lot more beneficial in terms of gaining admission into dental/medical schools given that you earn great GPA while you are in those programs. Another plus about MS in biolgoy or biomedical sciences is that you will be taking some hard core science classes that will help make you fist year of dental/medical school a bit easier. In MPH programs, you mostly take social science classes that wont' help you much in gaining admission. This fact comes straight from the adcom of many health professional schools (dental and med schools). I was in a biomedical science MS program and they offer a seminar class in which they invite adcom of different schools to come and give talk and advice about gaining admission. So the adcom specifically talked about MPH program and said it is a mistake for alot of students to chose that route during that year off. They thought it would help in gaining admission but they said MPH is an entirely different field. It's like you fail to gain admission the first time around, you then go on and take master in history or literature or something and thinking you can earn great GPA int hat and gain admission the second time around. But truth is, if you fail to gain admission the first time because your fail to show you are capable of handling hard core natural sciences (due to your GPA or DAT score), then you gotta prove it that you can by being in MS in bio or biomedical instead of being in a MS where you take social sciences. So in conclusion, you have to decide identistry/medicine is what you truly want. If it is, commit to it and try hard. Don't think of a back up plan.