1, local harm (1) affect the development of the maxillofacial: because most of the malocclusion is formed in the process of children’s growth and development, some of the malocclusion occurs, it will affect the upper and lower dental arches or the normal development of the upper and lower jaws, and make the deformity more and more serious. For example, in the case of anterior anterior malocclusion, when the upper and lower anterior teeth are in anterior relationship, the lower dental arch will prevent the normal forward development of the maxilla, making the length of the maxilla underdeveloped. At the same time, the lower jaw loses the constraints of the overdenture covering relationship of the anterior teeth under normal circumstances, and the force of the forward development of the upper jaw pushes the lower jaw to develop even further forward. In this way, with the growth of age, the upper and lower jaws interact with each other and make the deformity more and more serious, forming the developmental deformity of the middle 1/3 of the face concave and mandibular anterior protrusion, and with the development of the malocclusion, it presents a crescent-shaped face shape. (2) Impact on oral health: when the teeth are crowded and misaligned, due to the difficulty of self-cleaning can cause inflammation of the gums and periodontium, and caries. At the same time, the misaligned teeth can affect the health of periodontal tissues due to occlusal abnormalities. (3) Affecting the health of the stomatognathic system: severe malocclusion can affect the normal function of the stomatognathic system, such as severe mandibular retraction, open lip and open teeth can easily lead to mouth breathing, which affects the respiratory function; posterior clavicle can affect the function of mastication; severe mandibular protrusion can lead to swallowing abnormality; severe mandibular protrusion combined with open dentition can change the normal position of the tongue, which will affect normal swallowing function; anterior protrusion combined with open dentition will change the normal position of tongue, and change the relationship of the tongue and the teeth in swallowing; anterior protrusion will affect the normal swallowing function. affect the normal swallowing function; anterior open bite and severe mandibular protrusion will cause abnormal pronunciation; malocclusion will cause the position of teeth and jaws to be abnormal, and there will be interference of dentition, which can cause jaw opening and closing of the mouth, anterior extension, and lateral movement disorders, which will affect the normal function of the temporomandibular joints, and there will be organic lesions of the temporomandibular joints. (4) Affecting the appearance: various types of malocclusion will affect the appearance to different degrees, which may present deformities such as open lips and exposed teeth, bimaxillary protrusion, and the lower 1/3 of the face is too long or too short. 2, systemic harm Misalignment will not only affect the health of the oral and maxillary system, but also cause damage to the whole body. When malocclusion is serious, the chewing function is obviously reduced, which can cause digestive disorders and gastrointestinal diseases. In addition, the deformity of face not only affects the appearance, but also affects the socialization and career choice, causing mental and psychological abnormalities.