That's a tough one because they could all be "useful". I emailed my target school's admission director a while ago with a similar question, and this was her response:
----"The courses that you named previously will prove to be very helpful. I would also look at taking the following if your schedule allows: histology, microbiology, genetics, and human anatomy"
-----The courses I mentioned were "molecular cell biology as well as an anatomy and physiology course".
Final Answer: You may want to contact a few of your "favorite" schools and see if they prefer any specific course. The courses you mentioned are "above" the pre-reqs of most dental schools, so it may come down to school preference, and what you find most interesting/in which class you think you can get a high grade. If you have to sign up for this class ASAP, I would probably vote for Molecular Cell Bio. Anatomy and physiology are very useful, but at its core, dentistry is focused on the teeth/mouth/gums/jaw etc. And I just think molec cell may look better for all the micro bio-esque classes we may encounter in dental school.
Just my 2 cents!!!