I concur with this statement. With how far along you are, you have to make to to basically do the best you absolutely can on the DAT. In my opinion, a 20 or 21 AA will not be enough. 23+ is really the only way to prove that you learned it all. Even then, the DAT shows nothing about long-term work ethic, and that is why the DAT as well as GPA are both important in different ways.
Before I get going, I want to say this is my opinion as a Rising Senior undergrad Biochem major. Opinions are like buttholes, everyone has one and most of them stink!!
I am gonna be a critic here, so just bear with me: With a 3.0 sGPA, how are you going to explain to adcoms (that is, IF you get an interview at a school) that you deserve to be given a spot in dental school when you graduated EARLY AND volunteered 100+ hours and shadowed 120+ hours? I have spoken to dentists on adcoms who would question why you shadowed 120+ hours and gave 100+ hours of community service time when you couldn't even keep your grades up? Dental school is harder than any undergraduate program, especially because of the time constraint. I've also heard from many people that they really hate when they hear a student who has hundreds of shadowing hours and they think that continuing shadowing will help their chances of getting into school. 40-60 hours of good quality shadowing is PLENTY, in my opinion, to know you want to go to dental school and pursue dentistry.
Also, if you are scared of taking upper level biology classes because they are really hard and will make your GPA drop even MORE, are you REALLY prepared to be accepted into dental school? You should be kicking upper-level courses butts! Dental school is only harder.
Again, I was really critical, but only because it seems to me you need to be very critical of yourself from here-on-out. You are gonna have to kick the DAT in its butt! Good luck studying!