Here is my own opinion and experience as a chemistry major.
At my school one can choose either B.A. or B.S. to graduate. 90% of the undergrad senior class just got out with B.A.'s. Those who want a B.S. have to do some more course work than the average Joe, including 2 semesters of Computer Science Programming, Calculus I & II, 3 more advanced graduate-level chemistry courses, 1 extra course called "the Contemporary Chemist", and 1 full year of independent research in chem professor's lab. I choose to do B.S. because it just looks a little funny to me to get on my diploma a Bachelor of Arts in Chemistry major. Of course, most others would say I am totally wrong.
But I think for research-emphasized dental schools like Columbia and Harvard, having a B.S. matters a little bit - if the two applicants have otherwise very similar statistics.