1, severe skeletal deformity of maxilla or mandible, such as excessive protrusion of anterior teeth, labial process, brushing teeth, etc.
2. Bad habits seriously affect the development of teeth and jaws. For example, the habit of biting your lower lip, eating your fingers, breathing through your mouth and sticking out your tongue.
3. Serious dislocation of individual teeth, such as tooth distortion; Individual teeth are malocclusion (the upper teeth bite inside the lower teeth).