In a normal tooth, the upper front teeth are in front of the lower front teeth. If the opposite phenomenon occurs, that is, the lower front teeth are located in front of the upper front teeth, it is often referred to as “encephalitis”, which is medically known as anterior teeth retrusion. “It is a common malformation in children in China, which has a serious impact on oral function, facial aesthetics and psychological health, and the symptoms are gradually aggravated as the patient grows older. The following is a brief introduction to the causes of the ground. A, bad oral habits 1, bad breastfeeding posture, such as improper bottle feeding, the lower jaw needs to suck forward hard, can cause anterior teeth anterior teeth together. 2, have biting the upper lip or jaw forward bad habits, resulting in anterior teeth anterior teeth and jaw protrusion. Second, local disorders during the period of teething 1, retention or early loss of milk teeth can cause individual anterior anterior teeth or most anterior teeth anterior teeth together. 2, premature loss of upper milk molars, the upper permanent anterior teeth posteriorly, can form anterior anterior teeth together. 3, Insufficient wear of the milk cusp teeth, higher than the arch plane, in order to avoid the possible early contact of the maxillary and mandibular milk cusp teeth, the lower jaw will move anteriorly or laterally, forming a pseudo mandibular protrusion with anterior anticuspid or anterior cross anticuspid. 4, congenital absence of upper permanent incisors, such as congenital absence of common maxillary lateral incisors, may cause the anterior maxilla to underdevelop and form anterior anticuspid. Third, disease 1, due to chronic inflammation of the palatal tonsils or lingual tonsils and stimulation of the mandibular protrusion, over time, can lead to anterior anterior teeth combined with mandibular protrusion. 2, post-operative patients with cleft lip and palate often have underdeveloped upper jaw, which can easily lead to anterior anterior teeth and near-mid malocclusion, with relative mandibular performance protrusion. 3, rickets patients, their calcium, phosphorus metabolism disorders and abnormal dynamics of the facial and jaw muscles, often lead to more serious mandibular protrusion or anterior teeth open malocclusion. 4, endocrine disorders, such as hypopituitary hyperfunction, can cause mandibular protrusion deformity. 4. Hereditary With obvious family history, and significant mandibular and facial deformities.