No but it would be a great skill as a dentist. First of all, our mouths and face play a huge part of general human communication. Second, you will be interacting with various types of patients and people every day as a dentist, so public speaking skills will come in handy there.
Not sure what major you're doing, but most health related (like biology) majors require a public speaking or interpersonal communication class. Not the most fun, but helpful, especially if you have that fear.
I am sure before you graduate, you will be required to present a so called "grand rounds" presentation in front of your class mates and professors. It is not a long one but that was what I had to do. Pubic speaking was never my thing until I started my career in 2000. I still remember being so nervous in my public speaking class where I almost pee in my pants back when I was in undergraduate school. But now, I actually thrive when I am on the podium giving CE classes. In fact it is an enjoyable experience where I look forward to every time I am miked to speak. At the end of this month, I am giving a day long course for the California Academy of General Dentistry in the beautiful Newport Beach, CA and I can't wait for that day to come. I hope the cold weather will clear up by then. DP
My advice is to learn from shadowing. I haven't shadowed yet, but from what I read, shadowing is just sitting around and look at dentist treating patients.
Just observe your dentist closely and see how he/she talk to their patients. I think you'll learn a lot from observing a dentist than taking a course in speaking.