I would not retake this for the purpose of university admissions. This is a really good score. The only reason that I could possibly see to retake this would be if you just want to do it to find out whether you can get closer to 1600 just for your own curiosity.
I understand that the majority of university students change their major at some point. However, you should nonetheless budget to make sure that you would be okay if you stick with your current intention of being a dentist. You should avoid or minimize debt as much as you reasonably can for the entire path (dentists make a reasonable salary, but even then debt can get out of hand). Given this I wonder why you would attend U.Michigan out of state rather than Rutgers in-state. I have known quite a few people who graduated from Rutgers and they have consistently impressed me. The school must be doing something right.
It is hard to chance you for top schools and dental programs, but I think that you are doing very well.