I actually know nothing about Dr. Guerin except that he employs Dr. Po. Dr. Po is very nice but quite incompetent I think. She did two fillings for me about 6 months ago, and I have had problems with both of them since day one. (One's pretty loose, the other too big.) I'll have to have both fixed next time I go for a check-up, but frankly, I won't go back to her.'
Writing a year later: I went to another doctor in Dr. Guerin's office, Dr. Marhew, and frankly my husband and I didn't think much of him either.
So Dr. Guerin's office, as conveniently close to the Tufts campus as it is, is probably best avoided.