I love iced tea, so I sip on diet iced tea most of the day. Any beverage will do but be very careful about sugary drinks which can really do a job on your teeth. Sucking on sugar free candies or chewing sugar free gum can also help. I use a mouth moisturizer at night before bed called Oralbalance. It is a gel you put on your tongue and gums to keep from getting so dryed out during the night.
Artificial saliva is also available.
My joint pain is relieved by using an over the counter pain reliever. I also use a moist heating pad. I also try to rest the joint more when it hurts. Sometimes the first sign that my saliva gland is acting up is my teeth may hurt and I have a headache. Most times though, I just wake up with a swollen face and jaw.