Usually we talk about “deflated mouth”, mainly manifested as the upper lip is sunken or short, or the chin is relatively protruding forward, the lower front teeth wrapped in the upper front teeth outside, commonly known as “ground bag sky”, “pig waist face “The professional term is “antimandibular deformity”. The cause of “deflated mouth” is more complex, mainly caused by tooth loss in the elderly, while most cases in young people are accompanied by deformities of the upper and lower jaws. We know that if the upper jaw is underdeveloped and retracted, it will cause a depression in the middle of the face, manifesting itself as a sunken upper lip and collapsed nasal side; the lower jaw is overdeveloped, resulting in an overly long chin, a protruding lower lip and protruding lower teeth biting on the outside of the upper teeth, causing a “backbite”. The “deflated mouth” not only affects facial appearance, but also has a negative impact on chewing, pronunciation, swallowing and other functions. The main treatment for “deflated mouth” in young people is a combination of orthognathic and orthodontic treatment; first, orthodontic treatment to match the upper and lower teeth, and then orthognathic surgery in adulthood (usually after the age of 18) to bring the jaws into the desired position and restore the position of the upper and lower jaws. If the patient’s upper and lower jaw teeth match better, orthognathic “surgery first” treatment can also be considered to quickly improve the facial appearance.