JYD--
Well the first thing is shadowing really shows you what dentistry is all about. The reason why shadowing is important (besides you giving up precious time and doing work for free) is it shows the ad-com your serious about dentistry. It shows them you know what you're getting into and will be familiar with some of the jargon/lingo/terms. I did a ton of volunteering/shadowing/assisting. The best way to approach this is ask your own dentist. If you're away from home, call a dentist up who is in your town, and just introduce yourself as a student who is pre-dental and would like to come in to shadow. If its ok, they may ask for a resume, so the doctor can learn a little about you. I was REALLY lucky. I only made one call and the receptionist did the rest for me. She talked to the dentist, called me back, and told me to come in and meet the doctor. That was fall of 2001. Now this doctor is my mentor, who takes me fishing with him, wrote me a letter of recommedation, and helped me take independent classes (I created a couple of classes with him).
So in essence, should you shadow? Yes. Besides learning about dentistry, you may just develop a relationship that will further your interest in dentistry. Shadowing is cool, but once you got the relationship going you'll get a chance to do some REALLY cool stuff!!