Moving to hSDN.
I'm inclined to say that your GPA in high school doesn't really matter too much- that's more for undergrad admissions, and the undergrad you attend doesn't matter to dental schools. Your undergrad GPA and your DAT score are what matter, but you have plenty of years before you have to worry about that.
If you're planning on applying to BS/DMD or BS/DDS programs though, then you should keep your GPA as high as possible, and score as well as you can on the ACT/SAT. Strive for the highest GPA you can get 🙂 Good luck!