I. Dental and maxillofacial malformations (a) Dental and maxillofacial malformations can be divided into: 1. Developmental malformations: due to abnormal growth and development of facial bones; 2. Acquired malformations: due to trauma or other external factors resulting in facial deformities or tissue defects. (2) Dental and maxillofacial malformations can be divided into: 1, anterior and posterior jaw development abnormalities: such as maxillary protrusion, maxillary recession, mandibular protrusion, mandibular recession, etc.; 2, vertical jaw development abnormalities: such as open and closed, long face syndrome, short face syndrome, etc.; 3, lateral jaw development abnormalities: such as wide face deformity, bite hypertrophy, jaw angle hypertrophy, etc.; 4, chin deformity: such as under or over chin development; 5, facial asymmetry Deformity: such as hemifacial short deformity, unilateral mandibular overdevelopment, hemifacial jaw angle hypertrophy, progressive hemifacial atrophy deformity, etc. Orthognathic Surgery Orthognathic surgery is a discipline that uses surgery and oral orthodontics to combine to treat dental and maxillofacial deformities. It is a combination of surgery and oral orthodontic techniques that can achieve satisfactory functional and morphological treatment results that are difficult to achieve with surgery alone or oral orthodontic treatment. Generally speaking, orthognathic surgery can be performed after the age of 18 (after the cessation of growth). The orthognathic treatment is designed prior to surgery and is usually followed by orthodontic treatment to ensure that the occlusal relationship forms a sharp fossa relationship and to prevent recurrence. Orthognathic surgery mainly refers to the correction of severe bony malocclusion after growth and development is completed with surgical methods. Orthognathic surgery requires the cooperation of orthodontists and oral and maxillofacial surgery to ensure that the occlusal relationship and jaw deformity are well corrected. The principle of orthognathic surgery: 1. The upper and lower jaws are planned to be truncated, displaced through three degrees of space, and reassembled into an ideal position for the upper and lower teeth. Before orthognathic surgery, a number of delicate evaluations must be done, including the analysis of frontal and lateral facial x-rays and occlusal models, to develop a treatment plan for the patient’s situation and needs. 2. Before orthognathic surgery, a period of orthodontic treatment is often required to ensure a more appropriate movement force and a stable bite during the surgery, and after orthognathic surgery, continued orthodontic treatment is required to make the final minor adjustments to the position of the teeth. In a few cases, complications such as numbness of sensory nerves or poor bone healing may occur. It will take about one week to rest and eat liquid food after the surgery. Within one month, you will recover completely.