We began bringing my daughter at age 3 and it was good- I learned a lot about what I was doing wrong (oops!) Fruit roll ups, fruit snacks, sippy cups!
I am not sure what area of MA you are in, but we go to the KIDS DENTIST in West Springfield. They have DVD Flat screen players above every chair in the office- THe first time my 3 year old freaked! All they did was count her teeth and do a quick cleaning. We went back 6 months later and she did WONDERFUL! They were able to do everything but flouride.
I would definitely bring her, just to give her the experience. My 5 year old is great about going- he loves it!
Good Luck!