For those of you who had problems finding a dentist to shadow, there is a likely reason. Calling or emailing is NOT the way to set yourself for succeeding. When I retire from the Navy and open my practice, I'll reject every individual who calls me to ask. If I am going to give my time to help you, then you had better get off you butt and show some commitment. You are trying to be a professional. There is nothing professional about getting on a stupid phone and calling or emailing people begging for them to help you. Dentists are more likely to help you if you take the time to go to their office, set up a time to meet with them and fit your volunteer time into their schedule.
So, before anyone here chooses to call around, think again. Be a true professional. Get off your butt and make your rounds.