i'm teaching 5 AP courses to high schoolers... 3 AP Chem, 2 AP Physics. I'm teaching in Florida, so what i say is pertaining to FL but may pertain to other states....
I have a degree in Biochem (which is considered chemistry by the state)...so that alone qualifies me to teach w/in the field of chemistry, and i need to take a physics qualifying exam sometime in the spring to get my certification for that subject.
The certification exams seem very simple, so one shouldn't have an issue getting certified if you study some.
You don't need an education degree, just a degree. A science degree will be most helpful since it usually clepts you out of taking a qualifying exam.
Good luck, it is probably one of the best ways to spend the yr off between college and dental school. It looks awesome on your application, and gives you something interesting to talk about when the infamous, "how have you been spending your year off?" question arises.
jb!