Now most people on here are going to say that you need to do well on the DAT. Thats a given. Your grades seem to indicate that you had no real direction on what you wanted to do. But now you do you want to get into dentistry. If you do really well on the DAT, 20 above, then go ahead an apply this year.
Otherwise don't waste your time and besides getting rejection letters can be frusturating.
Your taking all the classes that you did not do well in. So that means your going to get at least a B or better. Nothing less.
Letters, you need strong letters. The dentist that your working with, should write you a strong letter. Express to him or her that your grades are not perfect, and that you need them to somehow get the attention of the ad coms, that although my grades are not that great, he has the potential to be a really good dentist. Same with Science professors.
Consider doing a post bac program at your local school, that is designed to bring up the grades.
Schools to look at if you do really well on the DAT.
NYU
Boston
Nova
Meharry(min)
Howard(min)
those are only I can think of that are willing to look past the grades.
I sure guys on here will add more.
Be sure to mention, how you are trying to improve your grades in your personal statement.
Worse comes, to worse, I would definetly call the schools that your interested in, explain to them your grades, they can give you a definate answer to what you need to do to get an interview.
Finally applying early is key.
HD.