I am right there with you sister. I ended my second course of 25 radiation treatments 4 years ago, had the first 24 years ago. Right away my teeth started chipping, fillings fell out, simply falling apart. Oncologist says I need to go see oral surgeon, He asks "didn't they tell you to have all your teeth out before you started radiation"? NO..... I had radiation on my lower jaw, twice so it was apparently harder on my teeth than if you get it in other areas. Still, I see people here talking about dental issues all the time and they had no radiation, just chemo. So it's a problem. I went to a Dentist and told them I wanted everything that was questionable fixed before treatment even started. Still had troubles.
You will have to talk to the doc and Dentist and see what can be done. I know they usually don't want you having anything done during treatment. Better make a call!
Good luck to you.