Are you clenching your teeth while asleep (or awake) besides the gum chewing? 30 minutes every other day doesn't sound like much at all, I doubt your lower third would get smaller from that little activity.

@paperbag

i dont know i want to continue chewing do you have any tips to chew properly without toching my teeths?

How can you expect to chew without your teeth touching? If you're really getting lower dental height just from chewing gum that infrequently, you should back off doing it. To me, that type of result would only happen through clenching. A few months ago, I tried hard clenching while moving my jaws side to side to lock in tongue posture and experienced brief positive sensations until my bite felt further misaligned, so I stopped. Try to be mindful of what your teeth/jaws are doing at rest; I can't believe that chewing gum could do so much damage unless there's a preexisting problem with your teeth.

Hi,

What kind of gum do you use? Regular chewing-gums are too soft to be chewed with force. And Just one piece at a time Is too small 

I used them for tongue chewing only.

You should get a quite hard gum or eat some harder food like jerkys. The bolus has to be rather big too, because It make the pressure you apply to be distribuited on a larger area of the dental arches evenly.

@kyte

chios, how many gum should i chew per session?

Enough to avoid the teeth to hit each other, I guess

Rely on this video 

https://youtu.be/MNuVYBYfbps

And read the description! In particolar the last line

Do you bite edge to edge? Or mostly on molars? 

@slipnkot666 

Do you mean worn down smaller?