At my last dental exam, dentist said gums were getting to be an issue. Try a water pic. Did it for six months while learning not to spray the mirror or myself so much. Got a "good gums" during my pre-radiation exam. Start off low pressure and may want to talk to doc before considering it.
P.S. talked to a guy just finishing rad/Chem. He said the salt/baking soda gargle was effective for throat care. Don't see why it wouldn't help with tooth care as well.
I'm planning to use the pic during my treatment and may consider dissolving saltbaking soda in the pic water. I'll see what doc says. Good luck.