Mike mew says that teeth should be touching lightly but the problem is if your jaws are asymmetrical or masseters are imbalanced your jaw will close improperly.
Many people have these imbalances and they don't even know about it.
Their jaw may move sideways when they try to get their teeth together.
And if you try to get posterior third of tongue up your teeth will touch usually.
People with good teeth/bites may have maintained good posture while growing up
And if they mew they may get better results than those with bad teeth/bites.
But if your bite is bad it may really worsen things.
My third molars don't meet each other and simply keeping my teeth together with tongue on roof of mouth is not gonna help.
Basically only thing we should focus on is we are breathing through nose most of the time and lips are together.
So please think about consequences before doing anything like HARD MEWING/Mewing.
Maybe mewing can help with that. Im hoping keeping my tongue on the roof of the mouth and out of the way of the teeth will allow my molars to extrude (there is a better word but i forget) further.
Mr Mew the senior said a deep bite often comes from rthe tongue hindering the back teeth to come out as much as they should and my mother who used to be a dentist said that if you loose a tooth the one above or below will come out further so its forces against the teeth keeping it in.
If you have real issues with your bite and your teeth, you should probably go see an orthodontist and get a professional opinion. Mewing does work but it's not a substitute for braces.
Yea mewing will bring everything forward,including you asymmetries. My right cheekbone is maybe 2-3 mm in front of my left. This last year, I ended up bringing my right eye into a positive canthal tilt, with my left lagging far behind. I didn't start with uneven eyes, but I currently have them. I'm not worried, as I have identified the problem and have been fixing it. Things get weird before they get right!