Everyone is different in the after effects of radiation. I had parotid (salivary gland) cancer and my left gland was surgically removed followed by Proton Therapy radiation which only irradiated half of my face. This was 15 years ago. I never fully regained salivation, especially at night. I drink liquid all day and wake up often to drink at night. Surprisingly when I brush my teeth, I salivate. I have lost 5 teeth over the years and 2-3 more are on their way out. My tongue has a major sore and the lining of my cheek always has one or two sores. This is all due to the radiation and there is no cure. I did undergo hyperbaric chamber therapy to improve the sores, and it did, just not enough.
Hopefully, you will be one of the success stories, with little or no loss of teeth and a full salivation recovery. I wish you all the best.