I don't like how some groups think they can predict the prospective performance of a student in dental school based their past undergraduate history. A 4.0 student might have only maintained a 4.0 in order to get into a dental school and become a GP. There's little incentive for such a student to "gun" for every single arbitrary point on an exam in order to be top in their class when all they really need is a healthy understanding of the material.
I like what this Canadian study has to say, "Conscientiousness is comprised of traits such as organization, persistence, and purposefulness...Conscientiousness predicted academic or clinical performance or both in every year of dental training." There're not enough studies in this subject but I think this factor is very promising. (Full disclosure - I do not have time to read the entire article at the moment. I definitely will after I finish this paper. Senioritis...)
http://www.jdentaled.org/content/71/5/664.full.pdf+html
I would rather accept a student who had a poor academic history but is now goal-oriented, challenge-oriented, intrinsically motivated, determined/hard-working, curious, and organized (how a person with such a poor academic history suddenly becomes this way is beyond me) over a student with the opposite condition.