I think not. I am a 10 year user but I mostly use a nasal mask now but for my first 3 years it was mostly a full face mask. The next few I used a full mask for 4 days out of every week because my nasal passages got too blocked up and I needed to breath through my mouth. I have never experienced a pop when I open my mouth with the full face mask. I only experience pops when either my nasal or full face mask is pushed aside whilst sleeping on my side and sometimes when I open my mouth whilst lying on my back (which I now do sometimes)
I tried a chin strap for a while 2 or 3 years ago because my wife said I was now opening my mouth and the air was coming out of my mouth. It didn't work for me so I reverted to a full face mask which solves that problem.
I am also mostly a side sleeper and sometimes it shifts the mask when I roll over on my left and I get woken up. Maybe not so much a popping as a fluttering sound.
I have always used Autoset (APAP) starting with an s8. I now have a S10. I am suspicious that having the upper limit at 20 is a problem when you accidentally move the mask with your head buried into the pillow it forces air out at high pressure and cause a bit of a pop. It seems to me it even "blows" you mouth open if the pressure comes on too high. If your sleep study doesn't require such a high setting as 20 dial it down just above what your study said you need say to 15 for instance. I think the pops and blow outs reduce when you displace the mask at the lower setting and you may not wake. With the Autosense 10 on all auto settings I also think it will sense when there is a big leak. But they all blast to the max if there is a leak and its harder to keep the seal at the higher pressure. My wife says it even forces the air out through your lips.
I also suspect that if you have a nasal mask and open your mouth APAP may suddenly blast up to the much higher setting (treating it as a leak) and this is likely to cause a popping sensation too, so dialing down the upper limit may reduce the popping.
My view of APAP is that you need to adjust occasionally and even mix it up because just when you have conquered one bad habit you develop another. In the middle years I found swapping between a nasal and a full face mask every 3 to 4 days solved some problems.
I like the auto ramp on the Autosense 10 and whilst it is default 4 start try slightly higher starting pressure (5 instead of 4 or even 6 and see if that works). I used 5 on my S8 and a longer ramp up as the slightly higher start pressure built the habit of closing the nasal passage into the mouth. If it doesn't work then change back to 4.
I also had to train myself to sleep more side on (instead of burying my face in the pillow which was my natural side on) I shoved a pillow between my knees for a few months and it kept me straighter reducing the mask shifting and popping stuff.
Experiment until you find the best variants.
Youi can practive tounge contol while awake all you like but when your jaw slackens as you sleep, a full face mask bottom edge will end up in your mouth and you will have a huge air leak as there is NO seal. I use a mouth guard and it keeps my jaw from sliding back and even if my teeth are not together, my mouth stays shut. The secret is to adjust the mask so the bottom edge stays planted where it should. About once a month, my jaw will slacken to the point where the mask is in my mouth in the AM but the other days, I usually now have ZERO leaks. I am using an Amara View mask that is pretty comfortable and seals really well unless the jaw-slackening issue occurs. I tried a nasal mask and it just didn't work for me at the pressure I use... the exhale holes were too small and the mask filled with moisture and I felt like I was drowning. Couldn't keep the thing on for even a 1/2 hour.
Hi DWalsh. I have used all 3 masks--nasal mask, nasal pillows, and full face--with no problems related to my mouth popping open. For many people who use a full face mask, the mouth only opens slightly and does not cause a problem. Some patients use a full face mask with a chin strap to help support the jaw. Wiredgeorge gives good advice about adjusting the mask appropriately. It should be snug but no too tight. Please keep us posted on your progress, and best wishes!