Posted by: Parsa

I have a narrow lower palate compared to my upper one

How do you mean this?

I have heard that keeping the teeth in contact during tongue on roof posture leads to a lower palate increase by way of the upper palate pushing the lower palate out. 

as in making the lower jaw (mandibular arch) wider, my jaw bone is barely visible

Hard to say for sure without a picture, but jaw bone barely visible could be a result of forward head posture. Turkey neck can form, as well as a buffalo hump. Mackenzie chin tucks are quite helpful toward remedying the posture. I believe I largely corrected my forward head posture by sleeping in a Mackenzie chin tuck, though some people report this is difficult. Pelvis may need to be tucked, but if I were you I'd go to a physiotherapist to get things verified. Over time, if you stick with your protocol for posture correction, you'll have a visible jaw line again. Try to keep your occupit raised at all times too.

There's also a lot of helpful information on this forum about techniques for correcting posture. Be patient and don't give up, this is one of those things you might have to fight for.

Chewing is supposed to help encourage the mandibular arch to keep up with the maxillary arch.

Posted by: EddieMoney

Posted by: Parsa

I have a narrow lower palate compared to my upper one

How do you mean this?

I have heard that keeping the teeth in contact during tongue on roof posture leads to a lower palate increase by way of the upper palate pushing the lower palate out. 

Shouldnt teeth be together when doing mewing with tongue on roof of mouth'?

Posted by: Le_Fort_or_Bust

Posted by: EddieMoney

Posted by: Parsa

I have a narrow lower palate compared to my upper one

How do you mean this?

I have heard that keeping the teeth in contact during tongue on roof posture leads to a lower palate increase by way of the upper palate pushing the lower palate out. 

Shouldnt teeth be together when doing mewing with tongue on roof of mouth'?

Yes. My understanding is if you have proper oral posture, your widening upper arch will push out your lower one (in theory) since the teeth remain together. 

Also, I hear chewing increases masseter development which in turn leads to a widening of the mandible to accompany the larger muscle mass.

My teeth haven't stopped fitting nor does my lower arch look narrow compared to my upper. My mandible has also grown laterally thus making me less narrow faced so I assume the lower arch has widened. 

I have to get impressions of my new lower arch in order to see this for sure.