The practice is called orthotropics. I can vouch for this user's experience myself, have had difficulty breathing for many years which led to poor teeth and a narrow palate. Once I received a palatal expander i realized how important it was to keep tongue pressure flat on the roof of the mouth. I practice regularly now and have seem improvements to teeth, breathing, and facing structure. It's a shame this stuff isn't taught more. You can find more details in this video: https://youtu.be/eh9OqEd5z1k

Could you provide more resources that demonstrate the science, such a studies or journal articles? I was interested and didn't find anything.

Additionally I found this that seems to suggest skepticism: https://www.nature.com/articles/sj.bdj.2014.711

I understand your skepticism. But you should start with the orthotropics youtube channel. Obviously, not an unbiased source of information. But it's a start from which you can at least critically evaluate what they say.

Another thing to bear in mind is that scientific theories are obviously developed faster than they can be proven. And as long as what Orthotropics is not invasive you can try what they preach yourself and draw your own conclusions rather than wait for academic silos to try prove that the method works.

I am trying it on myself. The results are not magical, but I can feel them, I can breathe better. And at the end of the day that's what matters most

When pressing your tongue against the top of your mouth, do you keep your teeth close together or with a slight opening?

My mouth is closed but my teeth are not in contact.

Yeah busterbaxter has it right, Orthotropics is the name.

I push hard on the roof of my mouth as often as I’m able and have it in mind, as firmly as I think I safely can (bone is sturdy but I imagine it is possible to over-stress it), because I’m trying to actively remodel my face and there was some doubt in the beginning whether that was possible at all as an adult.

As of now the results are clear, my jaw swings farther forward and up, before it was compressed back by the rearward position of my maxilla. The differences are not huge - measured in milimeters, but the difference in articulation can be felt and seen. I actually remember the day I was able to shift my jaw forward to a relaxed position while closing it. My face is now shorter/squarer and broader in appearance. Previously it was consistent with “long face syndrome”. Look up photos of that and you’ll see what I see now: a rearward maxilla, and a jaw forced to swing low to meet it.

Anyway, I’m still at it - my goal is to move my cheekbones to meet my brow. Currently they’re set back a bit, but progess is noticeable. Sounds crazy, I know, but it’a true. :P