I chose dentistry because it's quite unrelated to ChemE.
Seriously, I hated engineering...but I do think that our engineering backgrounds will help us a lot in d-school. As engineers we know how to apply concepts to solve problems and we're practical and creative. I hear we should do well in materials too.
As far as ChemE specifically, I don't know, but maybe the fact that chemical has more gray areas (because of the nature of chemical rxns) we might be more comfortable with the gray areas of dentistry/medicine.
But, I'm really grasping...there's a couple other ChemE's around here, maybe they have something more intelligent to say.