If the question is: are certain majors looked upon more favorably than others, I cannot say. I have never been on the admissions committee of any dental school, let alone an orthodontic program. I do think that it's safe to say that once you are into dental school and presumably doing well, what your undergraduate major was is very unlikely to carry any real importance when you are applying to orthodontic programs.
As far as dental school is concerned, there is something to be said about having a well-rounded education, including humanities. If you're already inclined to follow a biology or biochemistry major, either will be a good preparation for dental school. For that matter, a major in the physical sciences is just fine (I was a chemistry major).
I should point out that AFAIK all dental schools will require you to take a basic biochemistry course. While it may be possible to get advanced placement, I've never heard of it being done. (As an aside, I took 2 years of college chemistry in high school--including biochem, but failed to get placement in college. This meant I got to take basic biochemistry THREE TIMES--with an abridged version of the same text I'd used as an undergraduate when I got to dental school.) So in a way, it might be better to major in something you WON'T be getting again in dental school.
Good luck to you!
Last updated Nov 30 '17 at 15:28