Hi there - mine was just a mouthful - capful, I think it's just as affective - you need to see a dental oncologist ASAP! Radiation does a number on your mouth and gums - and teeth, it can cause mouth dryness which leads to cavities and and over abundance of plaque (spit is important!!!) anyway you need flouride trays - use them daily to prevent dental fall out. My ccc has a dentistry dep. that was where I was sent immediately to be fitted for my trays. If you have to have a tooth pulled after radiation it can be a nightmare! (HBO dives etc...) try to save your teeth now ! Aside from saving on dental expenses in the future - radiation can cause osteonecrosis which if a tooth has to be removed - could lead to a mandiblectomy etc...
You don't want to go there!!!

Good luck with everything!! You'll be done in no time.