good question, I highly doubt it. I heard of very few get full rides to med school. Maybe due to lack of major research and research funds and more expenses with clinical instruments and teaching at dental schools.
I don't know about full ride but I do know a few classmates and schoolmates who received full four-year tuition scholarship. Dental school is a highly political place so getting it is just a matter of luckily running into the right people at the right time; on record it just doesn't exist and no one who got it will tell you. If you are of a particular "minority" (asians don't count) there are also full tuition scholarship simply because you are a minority; you know who you are so just ask about it. I knew of one particular almost 60 years old individual with full tuition scholarship who flunked out of my school and then got in the following year to Howard also with full tuition scholarship because she was a minority.