How to stop mouth opening, to use nasal pillows effectively?

[Pugsy]

- do nothing

is my leak to solve in the future or is acceptable ?

I would do nothing if it were me. As long as the leaks weren't causing me to wake up.
Are the leaks waking you up?
In this graph...one brief period where leaks are over the red line for maybe half an hour and the other time very short lived.



It's not the end of the world if we slide over into large leak territory briefly..especially if we don't slide to far above that red line.

Looks like a little bit of mouth breathing going on....those leak lines that sort of plateau (flat on top) are normally indications of mouth breathing. Most of the time...if it is mouth breathing...it's relatively small amount and the machine can easily compensate for it. It's not like the entire night is spent well above the red line.
Using a chin strap or tape comes with its own set of annoyances. I have done both. Yeah, I could get some nice perfectly flat leak lines but chin straps and taping caused me to wake often and ended up causing more of a problem ALL night long than 30 minutes in large leak territory caused.

Here's mine from the other night. It's not real perfect either but I slept well. Some nights are prettier and some nights worse.
I don't fret short lived amounts of time in large leak territory.



Now some people just HAVE to have nice perfect leak lines and will go to extraordinary means to get them....it all depends on how much they bug you and what you want to do about them. It's your choice.

[jwerley]

I would definitely try a couple of chin straps before I tried tape (I can't see myself ever using tape).

Thanks for the models of strap indicated. Unfortunately, keeping my jaws tight does not stop air coming out through relaxed lips

I had the same severe mouth opening problem that you are having. I tried all of the suggestions that you have so far been given and none of them worked....I was desperate to make something work, as I cannot use a full face mask. So I found on the internet, "Chin Ups". I use the "Boomerang" style and pull both ends up as far as I can. This purses my lips very tight together....no air escapes. That did not work alone as I had hoped for, so I had to add a chin strap and use both. I use the "Ruby Red" chin strap. This might sound like a lot of trouble, but it has been the only solution for me.....so thought I would pass it on.

Janice

PS I have No interest in this company other than being a happy customer!