I agree with Demitry - "Especially two 15's and one of them in a Natural Science." Many dental school did not too much concern if you get score of 15 in the QR section and they will say retake because at the GChem. However, it is all based on DAT with out other factors in your application package such the personal statement, working in the community services, GPA, etc.
You might be at the edge of the cut off line. If you don't get in this cycle then try again at the next cycle, right?
I did poorly ( really bad) in the RC section and most of school told me to retake. So, I am aplaning to retake some time Nov. to submit. If I recover DAT score well on Nov. then it would be depends on the school with space. If not I will go for next cycle, super early.
Good luck on your application process.