Brian makes a great point about the enzymes contained in the biotene products especially the gum. It may not seem like it is doing much but it does have lasting effects even after you are done chewing it. Gum chewing as well stimulates salivary flow even in impaired salivary glands. The mechanical action of chewing makes the brain stimulate the glands.
Make sure you are chewing sugarless gum so that you don't damage your teeth. Gum that contains xylitol helps reduce cavity causing bacteria.
Cheers,
Mike