Why do most dental schools require a significant number of hours shadowing a dentist?

When I went to dental school shadowing was not required. My only experience was as a patient. When I started dental school I was surprised how "difficult" dentistry could be. After all, my uncle was my dentist and he always made my care look easy. I had a lot to learn when I started school. I am not sure if I fully understood the difficulties involved with running a practice, seeing patients and making them happy. If I had shadowed I would have had a much better understanding about what is actually involved in being a practicing dentist. 

We are currently hosting a recent college graduate who is taking a gap year and I asked her how much shadowing she needs and she reported that most schools require 100 hours of shadowing. I think this is a good thing, since the amount of schooling required to complete a dental degree is both time consuming and expensive. 

Not all dentists are comfortable having a prospective dental student shadow them in their office, but many are and with a little research applicants should have no problem finding offices to host them. Shadowing may prevent them from making a costly investment  and help that dentistry is the right career for them. If it isn't they have time to make their plan B.