Schools don't prefer one over the other, but look at which one will give you the bigger advantage. Since you're interested enough in both of them, look at it objectively.
Which one will help you get a higher GPA? If one major has classes that are a little bit easier for you, then go for that one, because having a high science GPA is a big big advantage, while the drawback of not having health-related sciences is miniscule.
I'm not in dental school yet (start this Fall!!), but I would assume that as long as you take the big 5 non-prereq classes (Anatomy, biochem, physio, histo, and can't remember the fifth one), you might have a slightly easier time once you're in dental school becaus you wont be seeing the material for the first time.