if your GPA is stellar and you have good EC as well as Dental experiences I'd say go for it. apply and when you take your DAT in November, contact the school to let them know you took it and they will usually allow you to either email or fax them your scores until the official report arrive. THat is of course, if youre confident that your scores will be 20+ across the board.
lots of schools have deadlines later than Dec. anyway, your chances are a little lower with late application but you will still have a chance. Plus best of all if, BIG IF you don't get in this year and you reapply your chances of getting in multiplied because re-applying shows your dedication to the profession (assuming your GPA and scores are decent). I have a friend who reapplied after retaking the DAT a second time.. her scores were 18/19/18 but she got into all the schools she re-applied to ( UPENN, TEMPLE, NYU, STONY, BUFFALO, MD,NJ, PITTS, BU, plus a couple of schools in Texas) . She picked Temple and just started her first year this sept.
