Sorry I don't leave in Boston. But I do work for a Dentist in Maryland. Everyone in the office understands what I am going through. They recently got me gluten free prophy paste, which is the tooth paste your doctor or hygentist uses. They can get it from any dental supplier they use. If they won't, they could use pumice, that is used in every dental office.
Flouride treatments also can be ordered gluten free now, but it is not necessary for adult to have this unless there is a problem, so just don't allow them to give you any flouride treatment.
The only other thing I avoid is topical anesthisia. You just have to tough it up and allow the dentist to give you injections without it.
I suggest you find a dentist that is a good doctor and that you like, then hopefully he will listen.
PS-still checking on Listerine