I think I am not mouth breathing when my mouth is taped closed or when it is closed with Polident strips. But I always form a vacuum with my tongue
against the roof of mouth. I do this after I am asleep and I wake with most awful dry mouth you have ever seen. And my lips are still shut tight. I keep intending to buy Biotene or Oasis but just haven't done it yet. I just dread adding ANYTHING else to the nightly routine. But in the night when I wake with this awful mouth, I wish I had made the effort.