Nelie,
My treatment was coordinated through Dana Farber -- before I had any surgery or radiation, I had several consultations with the head and neck cancer team there, and they also set up my radiation plan. Since you have family/friends in this area, I'd encourage you to go ahead and try D-F for a second opinion.
My teeth were in good condition before I started radiation, and the consensus of my cancer team was that they could all stay in (and I still have them all). For some time now, I've been on a teeth-cleaning schedule of every 2-3 months, checkups with a periodontist at least twice a year, and extra careful brushing and flossing all the time. I've been fortunate that, aside from an occasional crown or filling, I haven't ended up with any major dental problems since then.
As most of us here can tell you, radiation to the head and neck area is no picnic, to say the least. If you do need it, we can give you many suggestions for coping with the effects and we're here to offer support. Also, feel free to send me a private e-mail if you have specific questions you want to discuss.
Cathy