Very dry mouth after years of doing ok

I have been on a CPAP machine for about 4 years, recently I have been awakened by dry mouth after years of not having that type of problem. The humidifier section of my machine was just replaced , but the issue persists. The sleeping area has not changed. In the past , if I set the humidifier too high, I used to get water in the tube. Now even at the highest setting , I don't get any sign of water in the tube. My equipment supplier switched me to a full mask and the dryness continues. I used a auto-titration machine last week, the pressure was lowered as a result. The lower pressure has not made any difference in terms of dry mouth. Interestingly, when using the auto-titration machine for a week, I did not get any dry mouth. My respiratory therapist checked the pressure in the CPAP machine and she said it was fine. Any suggestions will be welcome.

It would be interesting to know if you were using the same brand of machine when using the auto-titrating machine, and if all conditions were the same (humidifier setting, heated tubing vs. regular tubing, etc.). Even though humidifying PAP treatment seems simple, different manufacturers use different sensors and algorithms in their machines to measure room temperature and humidity. As for the mask change, some patients on nasal masks experience dry mouth if they open their mouth and air escapes. Patients wearing a full face mask sometimes experience dry mouth because of the air blowing into the mouth. Have you attempted to humidify the room you are sleeping in with a room humidifier? If conditions are dry where you live, this may help.