PrimaryTooth -
There aren't many DDS/PhD students in general, nor on this forum - we're a small bunch (with a lot of support from the NIDCR). I'm in year 7 of 7, just finished my boards, and all I have left to complete are (1) clinic requirements and (2) to defend my dissertation, so I'm in a very good place. I don't know anything about UConn's program, but I do know (as in have met a few times) some good people from UMB. IMO, Minnesota and OSU have some of the strongest programs in the country. Some of this will depend on your research interests -
being able to find a strong research mentor and a topic you love will drive most of the success of your program.
If it helps, I love what I'm doing, and am staying in research full time when I'm done. I don't know what your situation is, however it was agonizing for me to decide on the dual route after planning on a straight DDS the whole time I was an undergrad. Once I made that decision to go to the interviews, everything fell into place. PM me with any Q's. Good luck!
Oh - and whatever you do, be absolutely sure that you get to talk to 2+ people in any program before you commit to anything. Go back and extra day for lunch/coffee if necessary, bring your list of questions and don't be shy about getting answers to all of them. There's wide variation in the DDS/DMD PhD programs, and some of them go through quite dysfunctional periods (I think a lot of this is the lack of standard structure that the MD/PhD programs benefit from, plus the smaller number of students). I know that this sounds like basic advice, but it shocks the heck out of me whenever we have a new student start who hasn't met anyone in the program yet. It's only your future.