hi!!
I can all misconceptions about cc and credits. You can have any amount of cc credits. If you have 65 credits and want to apply to a school that has a limit of 60, the school will consider all your dental school pre-reqs first into the first 60 units. Unless you had to repeat your pre-reqs so many times, you won't go over 60 units in the first place. The pre-reqs are the units they care about so if it doesn't go over 60, you're fine.
In regards to the schools you can apply to, it is true that temple, tufts, and boston will not accept any cc units, but beware of other schools. In the adea dental school guide book, some schools will say that they do accept cc work, but they highly do not recommend it. Some schools will give you a limit of 30 units.