though i can tell you i know how HARD it is to get a 3.9 at UCLA engineering, it actually doesnt matter that much for dental school
3.4 in biochem at a reputable school (davis) is more than enough for dentistry, plus the major is in a field that has to do with dentistry instead of just a science background.
23,21 are excellent scores, shows that the test taker has put in exceptional time into his/her DAT studies
I would guess that both would get into alot of schools, however, that the 3.4/23/21 would get more interviews, and be embraced by more schools as an ideal candidate