The chin consists of the connection of the horizontal branches of the bilateral mandibles and is an important part of the lower 1/3 of the face. Its own morphological position and its harmonious proportional relationship with the upper and middle face is one of the important factors of facial aesthetics, and affects the shape and function of the lips. Poor development of the chin bone can lead to “pointed mouth”, “pointed face” or “bird-shaped face” deformity. Overdevelopment of the chin can cause “long face” or “horse face” deformity. Deviation of the chin can cause asymmetry of the entire face. Chin deformity can exist alone or occur simultaneously with other skeletal deformities of the jaw or face. The cosmetic plastic surgery treatment of chin deformity can be divided into chin filling and chinplasty according to the different surgical methods and surgical sites. Chin filling surgery Chin filling surgery refers to the surgical method of using autologous bone, artificial bone or other biological substitutes to be shaped and placed under the front of the chin bone to increase the length and prominence of the chin and improve the facial contour, mainly for the correction of mild to moderate small chin deformity with normal bite and relationship. 1, the surgical approach chin filling surgery can be used extra-oral approach and intra-oral approach, extra-oral approach due to the scar left under the can be less used at present, this article focuses on the intra-oral approach chin augmentation surgery. The length of the incision depends on the material to be placed. When silicone prosthesis is used for chin augmentation, the length of the incision is about 1-1.5cm because of the elasticity of silicone, and the depth reaches the surface of the periosteum, and a cavity is formed by sharp stripping with small scissors on the surface of the periosteum, the size of which is suitable for placing the silicone stent, and the cavity should not be too large to prevent the prosthesis from shifting after surgery. When using autologous bone or artificial bone for chin augmentation, the mucosa is made into a 4-4 “V” shaped incision, and the mucous periosteum is incised to reach the surface of the chin bone, and the periostealer is stripped to reveal the bone surface of the chin bone, so as to facilitate the fixation of the implant. 2, implant material (1) silicone implantation Solid silicone is the commonly used implant material, as long as the indications are selected correctly, it is still an effective method to correct small chin deformity. According to the preoperative design and the operator’s experience, the shape and size of the silicone prosthesis are carefully sculpted and trimmed. Since the most likely complication after silicone implant placement is post-operative displacement which affects the surgical result, the volume should not be too large when implanted. At the same time, attention should be paid to the symmetry of the front and back, left and right positions of the prosthesis. After adequate hemostasis, the wound cavity is flushed with antibiotic saline and the muscle layer and mucosa are tightly sutured. After surgery, the wound is fixed with an external dressing. (2) Medpor implant placement Medpor (POREX SURGICAL INC, USA), also known as high-density porous polyethylene, is a porous implant material with good biocompatibility and easy to sculpt and shape. After placement, it can be fixed to the bone surface of the chin bone with titanium nails at both ends, and there is no risk of prosthesis displacement after surgery. Since this material has a long arm, the transition between the lower edge of the lower jaw and the chin after insertion is continuous and natural, and the result is good. Chinplasty In the early 1980s, Bell [8] proposed chin osteotomy with extensive soft tissue tissues, which is an ideal method to correct various chin deformities because the blood flow of the chin bone segment is ensured and the postoperative bone resorption is greatly reduced, and the ratio of soft tissue changes after osteotomy is more similar. It is suitable for the surgical correction of chin recession, too short chin, too long chin, giant chin and deviated chin. 1, the basic osteotomy method chin osteotomy: in the lower lip lip gingival groove lip side mucosa design 4 to 4 “V” shaped incision, cut open the mucoperiosteum to reach the surface of the chin bone, periostealer stripping reveal the front of the chin bone, stripping range to meet the design of the osteotomy line is appropriate, try to retain the muscle attachment below the osteotomy line to ensure the blood supply of the osteotomy block; first use a small round drill to set out the middle line at the joint of the chin, and then set out the horizontal The horizontal osteotomy line is located below the bilateral chin holes and parallel to the jaw plane, 1-1.5 cm from the lower edge of the median chin, and is used to cut the bone along the osteotomy line with a compound saw. The bone chisel is inserted between the broken ends of the bone, and the distal bone block is completely freed by rotating and prying, at which time the osteotomy section can be repositioned according to the patient’s deformity and preoperative design to achieve the purpose of correcting the corresponding deformity. 2, commonly used chin osteotomy shift mode and indications (1) horizontal forward shift type. It is the most commonly used osteotomy in chin shaping surgery and is mainly applicable to patients with simple chin recession without any deformity of the left and right chin bone and vertical direction. (2) Forward lengthening type. It is suitable for patients with chin recession who also have short chin bone development in the vertical direction, and is a commonly used clinical method to correct small chin deformity. After the chin bone is truncated horizontally, the distal bone segment is lengthened in accordance with the preoperative design, and a small splint is used for strong internal fixation. The broken end of the bone is filled with autogenous bone or artificial bone graft to establish bone continuity and ensure bone healing. (3) Horizontal left and right displacement type. It is suitable for patients with normal chin height, bilateral chin nodes are basically symmetrical and located at the same level of chin deviation. The distance between these two lines is the distance to be moved horizontally. (4) Horizontal shift rotation type. If the chin is oblique and the bilateral chin nodes are located at the same level but the anterior and posterior directions are not the same, when the chin is shaped to move left and right, it should be rotated anterior and posterior at the same time. If the chin is oblique and the bilateral chin nodes are in the same direction but not at the same level, when moving the chin from side to side, the chin should be rotated up and down at the same time. (5) Shortening forward movement type. It is suitable for patients with a receding chin but too long in the vertical direction. During surgery, two parallel osteotomy lines are designed in the chin and the distance between the two lines is the height to be shortened. The osteotomy is performed by first cutting off the lower bone segment, then cutting off and removing the upper bone segment, and moving the osteotomy segment forward in the intended position. Steel wire or small titanium plate is fixed internally. (6) Shortening and retraction type. It is suitable for those who do not have a protruding chin and have a long vertical chin. After removing the bone segment to be shortened, the lower part of the osteotomy is set back and fixed properly. 3, the lower edge of the mandible chin body retrograde osteotomy correction square wide chin deformity From the morphological point of view, the chin part is located in the lower 1/3 of the face, is one of the important components of facial aesthetics. Therefore, when performing chin osteotomy, we should not only consider the shape and position of the chin itself, but also take into account the overall proportional relationship between the chin, the angle of the jaw and the body of the jaw. Especially for patients who require cosmetic reduction of facial bones, it is necessary to take into account both the morphology of the frontal view and the continuous flow of the curve of the mandibular angle, body and chin from the lateral view. In the past, not enough attention was paid to this aspect in both chin shaping surgery and mandibular angle osteotomy. Therefore, on the premise of ensuring good blood supply to the distal bone segment after chin osteotomy, it is necessary to explore a chin osteotomy method that is simpler to osteotomy and takes into account the overall coordination of the mandibular angle, body and chin. Based on our many years of clinical experience, we designed the surgical method of “retrograde osteotomy of the lower edge of the chin body of the mandible to correct square wide chin deformity”, which can well maintain the natural shape of the chin bone because the lower edge of the chin remains unchanged. For patients with a wide, uncoordinated lower face, this surgery can be performed alone or in conjunction with mandibular angle osteotomy and horizontal chin osteotomy. For patients with a combined wide chin, retrograde osteotomy of the lower edge of the chin body of the mandible (including chin node osteotomy) is performed at the same time as the curved osteotomy of the mandibular angle, which can not only make the osteotomy line of the mandibular body continue smoothly and completely avoid the second mandibular angle, but also achieve a more perfect face shape from the front.