Well, I think it does... I'll try to put it in perspective for you.
As an undergrad, you probably took an average of 3 classes per quarter/semester, roughly 15 credit hours. In dental school, you'll probably take about 6-8 classes per semester at about 18-20 credits.
It is much harder to learn 6-8 classes of new material and not been exposed to biochem, microbiology, anatomy/physiology. If you have 6-8 classes and have been exposed or taken biochem, microbio, and anatomy/physio, then you really only have to learn maybe 3-5 new class material. I've heard from first year students that if they haven't taken those classes in undergrad, they would be in a bigger bind trying to juggle all the new material. Besides, I think most people who don't have Biochem, Microbiology, and Anatomy/Physiology will be at a disadvantage because most students (i'm assuming...) will have already taken those classes in undergrad. I could be wrong about my assumptions....