Sometimes it's two steps forward, and one step back. As mentioned, adequate hydration is important, constant rinsing, brushing, drinking water before sleeping, using a humidifier, some sleep with their mouth open, so thay increases dry mouth, but there are snoring chin straps that may help if the doctor so approves. Milk enzymes replicates saliva, and lasts longer hydrating than water. Lemon drops candy, lemon water helps increase saliva, as does chewing gum, like ones containing Xyletol. Some medications cause mouth dryness, and illnesses, like kidney disease or impaired kidney function.

I hope this helps.