Mouth protrusion can be caused by bad habits, malocclusion or abnormal development of jaws, and usually requires orthodontic or orthognathic surgery. 1. Orthodontic treatment: for children, it is often caused by bad habits such as biting or open-mouth breathing. Early on, mouth protrusion can be improved by functional orthodontic treatment, quitting bad habits and using functional orthodontic appliances such as lip stops. In the later stage, the protrusion of the mouth can be improved by retracting the anterior teeth through fixed orthodontic appliances, which usually needs to be combined with tooth extraction and reduction for improvement. 2. Orthognathic surgery: For those who are not well treated by orthodontics or cannot be treated by orthodontics, orthognathic surgery is needed to trim the overdeveloped jaws and combine with orthodontics for joint treatment. If there is convexity of the mouth, you should go to the hospital in time for intervention to avoid affecting the facial aesthetics.