My RO also would not hear of it.
It does depend on the radiation planning, that is to say what gets nuked and what not (IMRT). In my case both parotids apparently survived. (one got partially fried). However, the sublingual and submandibular glands are dead. This means that have saliva albeit "only" the watery type**. There are still dental issues, but I do not need to carry around water all the time and I can eat a slice of pizza without water. (potato chips are out).
My advice is to ask the RO (or the person doing the planning) to show and explain the radiation plan (contours).

Best

M

** note I am not complaining considering!