David,
Has anyone mentioned flouride trays to you? If not, you'll want to look into this as it will become part of your "new normal." On of the side effects of the radiation is either decreased syliva production or decreased quality of syliva or both. As my dental oncologist explained it to me, syliva is 90% water and the other 10% consists of numerous compounds -- some of which help protect our teeth. As result of the interrupted syliva function, dental carries are another after effect of radiation. To counter this problem, he perscribed dental trays (similar to teeth protectors worn when playing sports) to be loaded with gelled flouride and worn every night for at least 10 minutes after brushing.
If you haven't already, you definately want to look into this.
-Brett