Dear Dr. _________,
I hope this email finds you well. Thank you for that informative lecture you presented to my class yesterday. You mentioned that you have been actively involved in organized dentistry for more than 10 years. If possible, I would love to meet up with you for coffee sometime to learn about how you became involved in organized dentistry, since that is one of my aspirations as well. I understand that you are very busy, so if you are unable to, I completely understand.
Thank you very much.