For me anyhow, an abysmal undergrad GPA was mitigated by doing well in a postbacc program and doing well on the DAT. FYI, I took the DAT twice: scored a 21 AA and 25 AA the second time- I wasn't exactly sure if the 21 would be enough, so took quite few practice exams and did better the second time around. One interviewer I spoke to told me that he "Appreciated the time I put in trying to turn my academic credentials from dismal to respectable." Of course, I was summarily rejected from all the dental Ivy's, which was no shocker, but have been granted accepted into some good programs in the past two weeks.