Hmm, I purposefully throw a bit of white (well, off-white, truthfully) in the ambient node (usually with texture attached to avoid heavy shadows on the teeth, which can make them look like they have huge cavities.  I also throw a tight glossy on, too, because I don't want the teeth to look dry.

Now I'm going to have to go look at my stuff and study the teeth and see if I'm guilty of over-polishing! LOL.