Malocclusion refers to the malformation of teeth, jawbone and craniofacial surface caused by congenital genetic factors or acquired environmental factors (disease, bad oral habits, abnormal tooth replacement, etc.) during the growth and development of children, such as misalignment of teeth, abnormal relationship between upper and lower dental arches, and abnormal position of jawbone size and shape. The main causes of malocclusion are: the incongruity between the amount of teeth and bone, teeth and jaws, upper and lower dental arches, upper and lower jaws, and jaws and craniofacial surface. The so-called osseous malocclusion is a malocclusion caused by the incongruity between the upper and lower jaws, the jaws and the craniofacial surface. The bony malocclusion in the anterior-posterior direction (i.e., sagittal direction) are: overdevelopment of the upper and lower jaws, manifested as upper and lower jaw protrusion; overdevelopment of the upper jaw or underdevelopment of the lower jaw, manifested as upper jaw protrusion, open lips and teeth, deep coverage of anterior teeth, deep overlap (dentition); underdevelopment of the upper jaw or overdevelopment of the lower jaw, manifested as mid-facial depression, anterior teeth retrusion (dentition). The lateral bony mis (dentition) are: maxillary lateral underdevelopment or mandibular lateral overdevelopment, manifested as posterior retrusion (dentition); maxillary lateral overdevelopment or mandibular lateral underdevelopment, manifested as posterior orthodontic lock (dentition), also called orthogonal span (dentition). Mild bony malocclusion can be corrected by orthodontic treatment, mainly by orthodontics, while moderate and severe bony malocclusion often require a combination of orthodontic treatment and orthognathic surgery.