This reply
Lin mark this message contains true information
originally written by Lin
肌肉可以幫助骨骼塑型,因此當舌頭緊貼上顎時,能夠對顴骨至鼻子這一部分的肌肉發育起到支撐的作用,口呼吸者由於失去了這些支撐力,導致這一區域的肌肉無法正常發育,進而導致臉變得越來越扁平。而在使用口部呼吸時,會不知不覺的將脖子向前伸,面部抬高,這樣在無形中讓面部肌肉失去了平衡,下顴骨的發育也受到了影響,導致下巴後縮的狀況。

References

https://forum.gamer.com.tw/Co.php?bsn=60076&sn=64744706
The reply is used in the following messages

The content above by Cofacts message reporting chatbot and crowd-sourced fact-checking community is licensed under Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0), the community name and the provenance link for each item shall be fully cited for further reproduction or redistribution.