1, local harm (1) affect the development of the jaw and face As most of the misalignment is formed during the growth and development of children, some misalignment occurs, will affect the normal development of the upper and lower dental arches or upper and lower jaws, and make the development of malformation more and more serious. For example, in patients with anterior anterior teeth, when the upper and lower anterior teeth are in anterior relationship, the lower dental arch will prevent the normal forward development of the upper jaw, so that the length of the upper jaw is not developed enough. At the same time, the lower jaw is constrained by the loss of the anterior teeth in a normal overbite relationship, and the force of the forward development of the upper jaw will push the lower jaw, more forward development. In this way, with the growth of age, the upper and lower jaws affect each other and make the deformity more and more serious, forming the developmental deformity of the middle 1/3 of the face sunken and the lower jaw protruding forward, with the development of malocclusion, presenting a crescent-shaped facial shape. (2) Affect the oral health When the teeth are crowded and misaligned, it is not easy to self-clean and can cause gingival and periodontal inflammation, and it is good to develop caries. Meanwhile, the misaligned teeth can affect the health of periodontal tissues due to abnormal occlusion. (3) Affect the health of oromandibular system Severe misalignment can affect the normal function of oromandibular system, such as severe mandibular recession, open lips and teeth can easily cause mouth breathing and affect the respiratory function; posterior teeth locking teeth together can affect the chewing function; severe mandibular protrusion can cause abnormal swallowing; severe mandibular protrusion combined with opening and closing can change the normal position of the tongue, changing the position of the tongue and teeth in the process of swallowing, and affecting the normal swallowing function; anterior protrusion combined with opening and closing can change the normal position of the tongue and teeth. The normal swallowing function will be affected; anterior teeth opening and closing and severe mandibular protrusion will cause abnormal pronunciation; misalignment will cause abnormal position of teeth and jaws and joint interference, which will lead to impaired opening and closing of the jaw, forward extension and lateral movement, and then affect the normal function of the temporomandibular joint and organic lesions of the temporomandibular joint. (4) Affect the appearance of appearance Various types of misalignment will affect the appearance of appearance to varying degrees, and may present deformities such as open lips and open teeth, double jaw protrusion, and the lower 1/3 of the face is too long or too short. 2, systemic harm Malocclusion will not only affect the health of the oral and jaw systems, but also cause damage to the whole body. When the malocclusion is serious, the chewing function is obviously reduced, which can cause digestive disorders and gastrointestinal diseases. In addition, facial malocclusion not only affects the appearance, but even affects the choice of social and professional life, causing mental and psychological abnormalities.