Pathogenesis Abnormalities in the proximal and distal mesial relationships of the upper and lower dental arches can be manifested as mandibular protrusion, proximal-medial malocclusion and anterior anticuspension. Most of the cases are caused by poor breastfeeding posture, retained or early loss of anterior milk teeth, congenital absence of upper permanent incisors, bad habits, insufficient wear of cuspids, systemic diseases and hereditary mandibular protrusion. Due to the different degree of anterior anterior anticuspension, the molar teeth are neutral, and in severe cases, anterior anticuspension, posterior proximal mesial synodontia and mandibular protrusion exist at the same time. Etiology 1, bad oral habits (1) poor breastfeeding posture, such as inappropriate bottle feeding, the lower jaw needs to suck forward forcefully, can cause anterior teeth inversion. (2)Bad habit of biting upper lip or extending the lower jaw forward can lead to anterior antral and mandibular protrusion. 2.Localized obstacles during the period of replacement teeth (1)Stagnant or early loss of milk teeth can cause individual anterior teeth. (2) Early loss of upper milk molar and backward movement of upper permanent anterior teeth can form anterior anticuspension. (3) False mandibular protrusion with insufficient wear of the milk cuspids above the dental arch. (4)Congenital loss of upper permanent incisors, such as common congenital loss of maxillary lateral incisors, can cause insufficient development of the anterior part of the maxilla, forming anterior anticuspension. 3.Disease (1)Due to the chronic inflammation of palatine tonsil or lingual tonsil and the stimulation of mandibular anterior extension, which can lead to anterior teeth counter and mandibular anterior protrusion in the long run. (2) Postoperative patients with cleft lip and palate often have underdeveloped upper jaws, which can easily lead to anterior anticuspension and relative protrusion of the lower jaw. (3) Rickets patients with calcium and phosphorus metabolism disorders and abnormal power of facial and jaw muscles can often lead to more serious anterior protrusion of the lower jaw or anterior teeth opening deformity. (4) Endocrine disorders, such as hyperfunction of the anterior lobe of the pituitary gland, can cause mandibular protrusion deformity. 4, hereditary anterior maltreatment combined with mandibular anterior protrusion with obvious family background, and the mandible and facial deformity is abnormal and significant. Clinical manifestations: anterior anti-tooth, face can be manifested as mandibular anterior protrusion, maxillary underdevelopment of concave lateral shape. Diagnosis and differentiation: (1) Odontogenic mostly due to local obstacles in the process of tooth eruption or replacement: often manifested as simple anterior teeth. The anticuspension is small, and the molar relationship is neutral or close to neutral. The shape and size of the lower jaw are basically normal, and there is no obvious abnormality in the maxillary-mandibular relationship, the chin is not protruding, and the face is basically normal. The mandible can be retracted to the front teeth, and there is no morphological abnormality in the X-ray cephalometric measurement of the skeleton, so it is easy to correct and the prognosis is good. (2) Bone origin is mostly due to genetic and disease factors: in addition to the anterior teeth, it is accompanied by jaw deformity. It can be manifested as blunt mandibular angle, long mandibular body, short mandibular branch or underdevelopment of maxillary anterior part. The chin is obviously protruding, and the mandible often fails to recede on its own. The face is mostly concave, sometimes accompanied by open jaw deformity. Its correction is difficult, and the effect of simple orthodontic correction is not necessarily good. This kind of anterior teeth can be categorized into 3 types according to the mechanism: ① Insufficient development of maxillary anterior part and normal development of mandible. ② Maxillary development is normal, mandibular overdevelopment. Underdevelopment of the upper jaw with overdevelopment of the lower jaw. (3) Functionality: Functional over-extension of the lower jaw due to poor breastfeeding posture, etc., resulting in mandibular protrusion and anterior teeth anti-correction, which is called pseudo-mandibular protrusion. If it is not corrected early, it may develop into real mandibular protrusion in the long run. (4) X-ray cephalometric measurements: (1) The SNB angle and facial angle are enlarged, indicating that the mandible is protruding relative to the skull base and the angle of the mandible is enlarged. The above measurements are normal in the case of odontogenic anterior antrum. In the case of mandibular anterior protrusion with maxillary retraction, the SNB angle decreases S-Ptm and Ptm-6 decreases. In the case of no maxillary retrusion, the above measurements are normal. If the ANB angle and AB plane angle increase and the AO-BO value decreases, it means that the upper and lower jaws are obviously not adjusted, and the above measurements are basically normal for those with odontogenic anterior antrorsion. ④ Facial protrusion angle (G-Sn-Pg”) increased, H angle (H line-N “P “g) decreased, and Z angle (FH-H line) increased, indicating that the lateral protrusion of soft tissues decreased. Upper lip protuberance (Ls-SnPg”) is reduced or normal. Lower lip protuberance (Li-SnPg”) increases. Maxillary protuberance (Sn-G) decreased or normal, mandibular protuberance (Pg”-G) line increased. 5. Treatment 1. Head cap and traction chin pocket orthodontic device. Suitable for early skeletal type anterior antipodal cushion tongue and groove orthodontic device, used in combination. 2, Anterior traction orthodontic device. Suitable for early skeletal anterior teeth in combination with maxillary underdevelopment and mandibular anterior protrusion, and can be used during the period of replacement teeth or the early stage of permanent teeth. Functional braces, such as activator or Frankel III. It is suitable for early skeletal anterior anticus, and can be used in the period of tooth replacement, especially in the late period of tooth replacement. 4. Class III traction orthodontic devices. Mainly used for adjusting the interproximal and intermaxillary relationship, commonly used in early skeletal anterior antipodal cushion braces, or fixed braces, or both can be used jointly. 5, Orthodontic removable maxillary, can be used alone or in combination with other orthopedic devices such as chin pockets and orthodontic appliances such as fixed appliances. Specific devices and applications. 6, Fixed braces, including edgewise square arch braces and Begg braces can be used to correct anterior anticuspension, often during the period of replacement or permanent teeth. When using Begg aligners, class III traction should be performed instead of class II traction, and the traction force is about 80g. 7. For adults with anterior anticus, combined orthodontic and surgical orthodontic treatment is required.