It can be related to the RA, or it could be Sjogren's Syndrome. Your rheumy should be able to help figure it out. I had to have a mouth biopsy to get a diagnosis. My suggestion is to treat the symptoms unless you must have a diagnosis. Hugs!

Pat

For the dry mouth of Sjogren's, I use Biotene mouth rinse, or a generic, as often as needed. For the dry eyes of Sjogren's, I use preservative free eye drops a minimum of 3 times a day. It is common to need the drops a lot more frequently. I know I need the drops if my vision starts to blur from eye strain or if I blink excessively.
I am confirmed as having Sjogren's due to lip and cheek biopsy.

I use biotene mouth wash

I've been experiencing dry mouth too. I didn't know if it was related to my RA.

My eye doctor told me to use natural tears for dry eyes. I don't have sjogrens disease yet. Ask your doctor what he thinks.

My mouth is dryer than it use to be, so I drink water a lot every day. But my dental hygienist when she cleans my teeth thinks I have normal saliva amounts.