John,
I was treated 18 years ago -- had at least one salivary gland removed during surgery and most of the others fried during radiation (that was long before the days of IMRT or amifostine). Over the years, it's been a combination of water, Salagen, Biotene products, and sometimes sugarless gum that have helped keep my mouth reasonably moist.
I brush my teeth at least 3x daily (mostly with an Oral B Plaque Remover electric toothbrush), use fluoride fairly frequently, floss every day, and have cleanings every 3 months. (I have a regular rotation where 2 of the 4 annual cleanings are done by my periodontist's hygienist, so I get his examination at the same time.)
I'm now 57 and still have all my own teeth. From time to time I've had fillings done, and a couple of gum grafts, but haven't needed any extractions so far.
Cathy