Hi Michelle,
I will relate my oral treatment.
Prior to treatment I saw a dentist who had a number of oral cancer patients. He performed my pre-radiation-treatment exam, and started me immediately on my twice daily flouride treatment using trays and 1.1% flouride gel.
He monitored my oral health throughout treatment.
He advised several times the importance of continuing the flouride treatment for life, regardless of the amount of saliva I would end up producing. According to him, radiation treatment damages the saliva glands such that the chemistry of the saliva changes. These changes result the saliva losing its tooth protecting function.
I also use toothpicks (along my gums and to compress my gums), a little bottle brush looking cleaner (by Dentek and others), floss, and clean my teeth all day long.
So here I am 4-1/2 years post treatment. I still use the trays twice a day. I have yet to have a cavity (knock on wood).
As an aside, I have had a couple of different regular dentists since I ended treatment, and I don't think they knew much about the effects of radiation treatments (one suggested I should stop using the flouride).
Anyway, that's my experience.
Best wishes,
Chris