Typically, the sentiment you are going to get from particpints in this sub-forum is as follows:
Dental school should not be a back up for medical school applicants.
From what you've provided, I would say you need to observe the field before applying. Just because you like medicine doesn't mean you will necessarily like dentistry. You are confined to the mouth and play the role of a small business owner (found in medicine too, no doubt), among other things. Admissions committees will see right through your transparent application with the lack of dental interest expressed. The dental application even asks if you are applying for other professional schools, so you can't hide it.
Here is my advice:
1.) Finish out the medical application cycle, or apply to medical school if you have yet to do so.
2.) If you get in, great. If not, and you still desire to pursue medicine, get feedback from the schools you applied to.
3.) Strengthen your application as needed and reapply.
4.) Repeat steps 1-3 until you get in or lose your desire to pursue medical school.
5.) Find another career.
Using dental school as a back up (if you get in) might lead to an unsatisfactory career that you can't escape because of debt and takes a spot from someone who has been chasing dentistry as a dream for years.
If, after observing dentistry for a significant amount of time, you find the field interesting and satisfying, no one else nor I would oppose your plan to attend dental school.
/rant
Good luck with whatever you decide; you're obviously intelligent and will find a great career in something.