The chin has distinctive facial features and personality traits, in the facial contour occupies a very important position, whether it is the front or the side, the shape of the chin on the overall image of the face has an extremely important impact, in recent years the shape of the chin is more and more people pay attention to, and often associated with personal character traits, normal or upturned chin is not only regarded as a sign of beauty, but also seen as wisdom, bravery, perseverance, Charming symbol; on the contrary, it is a reflection of weakness and indecisiveness. The aesthetic observation of chin mainly includes the following contents: chin height, chin protuberance, depth of chin-lip groove, the relationship between nose, lip and chin. 1, chin height chin height measurement method is as follows: front view, in the root of the nose and the root of the nasal column to do two horizontal lines, the face is divided into upper, middle and lower three equal parts, in the face of the lower 1/3 through the cleft of the mouth and then divided into three equal parts, the upper lip (including the skin of the upper lip, lipstick red) accounted for 1/3, the lower lip to the edge of the chin accounted for 2/3. many scholars believe that the coordinated facial structure should be the face of the face, face of the face in the face, face of the face of the height of the face, and the face of the face of the upper lip height with the lower lip of the lower lip height of the lower lip of the upper lip height and the lower lip of the lower lip of the lower lip height. Lower part of the upper lip height and lower lip height of the proportional relationship of 1:2 (women can be slightly less than 1:2), that is to say, the lower part of the face of the upper lip, lower lip (including lip red down to the chin-lip groove of the lowest point of the soft tissues) and the chin is still three equal parts. 2, chin protuberance chin protuberance measurement method is as follows: lateral view, first the ear screen and the lower edge of the orbit to make a horizontal line, and then from the soft tissue root point of the nose leads to a vertical line, extending down to the chin, in addition to the lower edge of the orbit from the front of the also lead to a similar vertical line. Accordingly, chin protrusion can be categorized into three types: (1) normal: the chin is between the two vertical lines; (2) protruding: the chin exceeds the nasal root vertical line; and (3) retracting: the chin retracts beyond the infraorbital line. The ideal degree of chin protrusion should be the point of the front of the chin is lightly attached to the root of the nose plumb line. 3, the depth of the chin-lip groove is the lateral view of the lower lip skin and the skin of the chin at the intersection of the lowest point of the soft tissue to the level of the point in front of the chin. It is reported that the Chinese beauty crowd chin-lip groove is deeper, the position of the chin of men and women, respectively, forward 13mm and 7mm, so as to show a harmonious but slightly protruding, clear contour of the chin. Men’s chin protrusion is greater than women’s, chin-lip groove is also deeper than women’s, so men show more obvious contour. 4, the relationship between the nose, lips and chin Evaluation of the relationship between the nose, lips and chin is coordinated and proportional can refer to the Ricketts plane, that is, the aesthetic plane: from the point of the tip of the nose to the point of the soft tissue in front of the chin line of the aesthetic plane (also known as the E line). The requirements of the upper lip from this line than the lower lip from this line a little farther, generally believe that the upper lip is about 4.0mm, the lower lip is about 2.0mm. Different races due to their genetic factors and cultural backgrounds are different, the aesthetic view is also different. Westerners have a long and narrow face, and western women are beautiful in terms of aesthetics with a sense of hierarchy and three-dimensionality. Oriental people have a relatively wide and short face, and in terms of aesthetics, an oval or goose-egg shaped face is the most beautiful, requiring a soft facial curve and a graceful arc in the side view. Chin plastic surgery With the improvement of surgical technology and surgical instruments, through the surgical method of the chin shape in accordance with the aesthetic principles of reshaping can achieve the purpose of remodeling the beautiful face. The cosmetic plastic surgery of chin deformity can be divided into chin filling surgery and chin shaping surgery, the former refers to the use of silicone or other biological substitutes after sculpting and shaping placed under the front of the chin bone in order to increase the length and protruding degree of the chin to improve the facial contour of the surgical method, mainly for the occlusal and relationship between the normal mild and moderate small chin deformity of correction. The latter refers to the reshaping of one’s chin by means of chin osteotomy and displacement, which is an ideal method for correcting various kinds of chin deformities, and is suitable for the surgical correction of chin retraction, chin overshortening, chin overlonging, giant chin, and deviated chin. 1, chin filling surgery chin filling surgery refers to the use of autogenous bone, artificial bone or other biological substitutes after shaping and placed under the front of the chin bone in order to increase the length of the chin and the degree of protrusion, to improve the facial contour of the surgical method, mainly for the occlusal relationship of the normal mild to moderate small chin deformity correction. (1) Surgical approach The chin filling surgery can be done by extra-oral approach and intra-oral approach, the extra-oral approach is less frequently used due to the scar left under the mouth, this article focuses on the intra-oral approach to chin augmentation. A “V” shaped incision is designed in the mucosa of the gingival sulcus of the lower lip, the length of the incision depends on the material to be inserted, when using silicone prosthesis for chin augmentation, due to the elasticity of silicone, the length of incision of the mucosa is about 1-1.5cm, and the depth is up to the surface of the periosteum, and the surface of the periosteum is sharply peeled off with a small scissors, forming a cavity, and the size of which is suitable for placing silicone stent, and the cavity should not be too big to prevent the prosthesis from moving in the postoperative period. When using autogenous bone or artificial bone chin augmentation, mucosa make 4~4 “V” shaped incision, cut the mucoperiosteum up to the surface of the chin bone, periosteal peeling sub-strip to reveal the surface of the chin bone surface, in order to facilitate the fixation of the implant. (2) Implantation material Silicone gel implantation: solid silicone gel is the commonly used implantation material, as long as the indications are correctly selected, it is still an effective method of correcting small chin deformity. According to the preoperative design and the operator’s experience, the shape and size of the silicone gel prosthesis are carefully sculpted and trimmed. Since the most likely complication after the placement of silicone gel is postoperative displacement, which affects the surgical effect, the volume should not be too large when it is placed. At the same time, it is important to pay attention to the symmetry of the prosthesis in the front and back, left and right positions. After adequate hemostasis, antibiotic saline rinse the traumatic cavity, tight suture muscle layer and mucosa. After the operation, the wound is fixed with an external dressing. 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 carve and shape. After insertion, titanium nails can be used at both ends to fix it to the bone surface of the chin bone, and there is no risk of displacement of the prosthesis after surgery. As this material has a long arm, it makes the transition between the lower edge of the mandible and the chin continuous and natural after placement, and the effect is good. 2, chin osteoplasty In the early eighties, Bell [8] proposed chin osteotomy with a wide range of soft tissue tips, because the blood flow of the bone segment of the chin is guaranteed, the postoperative bone resorption is greatly reduced, and the proportion of soft tissue changes after osteotomy is much closer to the ideal correction of a variety of deformities of the chin. It is suitable for the surgical correction of chin retraction, chin overshortening, chin overlength, giant chin and deviated chin. (1) Basic osteotomy method chin osteotomy: design a 4~4 “V”-shaped incision in the mucous membrane of the lip side of the lower lip and gingival sulcus, cut through the mucous membrane to reach the surface of the chin bone, and reveal the front of the chin bone with periosteal peeler, the peeling range is suitable to meet the design of osteotomy line, and try to keep the muscle attachments below the osteotomy line in order to ensure the blood supply of osteotomy block; use a small round drill to set out the center line at the chin center union, and then set out the horizontal osteotomy line, the horizontal osteotomy line is located in the chin center union, and the horizontal line is located at the chin center. The horizontal osteotomy line is located below the bilateral chin foramen and parallel to the jaw plane, 1~1.5cm from the lower edge of the chin; the osteotomy line is used to cut the bone along the osteotomy line with a resaw; when cutting off the lingual side of the bone plate, the operation should be accurate and gentle, to avoid damaging the lingual side of the muscle and soft tissues. The bone chisel is inserted between the broken ends of the bone, rotated and pried so that the distal bone block is completely free, at this time, according to the patient’s deformity and preoperative design of the osteotomy section can be re-located to achieve the purpose of correcting the corresponding deformity. (2) Commonly used chin osteotomy displacement methods and indications Horizontal anterior displacement: the most commonly used osteotomy in chin contouring, mainly applicable to patients with simple chin retraction without left-right and vertical deformity of the chin bone. Anteriorly shifted lengthening style. It is the most commonly used method for correcting small chin deformity in clinical practice. After the chin bone is horizontally truncated, the distal end of the bone is lengthened according to 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. Horizontal left-right displacement: It is suitable for patients with normal chin height, bilateral symmetry of chin nodes and chin deviation at the same level. During the surgery, the midline of the face and the midline of the distal bone segment itself are determined in the chin bone, and the distance between these two lines is the distance to be moved horizontally. Horizontal shift rotation: If the chin is skewed and the bilateral chin nodes are located at the same level but the anterior-posterior direction is not the same, when the chin is shaped to move left and right, anterior-posterior rotation should be done at the same time: If the chin is skewed and the bilateral chin nodes are in the same anterior-posterior direction but are not located at the same level, when the chin is shifted left and right, up and down rotations should be done at the same time. Shortening anteriorly : Suitable for patients who have a retracted chin but are too long vertically. During the operation, two parallel osteotomy lines are designed in the chin, and the distance between the two lines is the height to be shortened. The lower part of the bone is truncated first, and then the upper part is truncated and removed, and the truncated part is moved forward in a predetermined position. Wire or small titanium plate is used for internal fixation. Shortening backward style: It is suitable for those who do not have a protruding chin and the chin is too long in the vertical direction. Surgical osteotomy with shortening forward, to be shortened after the removal of the bone section, the lower part of the osteotomy section back and properly fixed. Chin plastic surgery precautions 1, women should avoid physiological period; 2, physical health, avoid colds and other systemic diseases; 3, before the operation should stop smoking. Aspirin, birth control pills and certain anti-inflammatory drugs can cause increased bleeding, so these drugs should be discontinued 2 weeks before surgery to avoid bleeding during and after surgery; 4, avoid breakouts, stomatitis, gingivitis and other conditions in the surgical mouth, it is best to scaling 2 to 4 weeks before surgery; 5, serious cases of pre-surgery to take X-Ray film, communicate with the doctor, according to the situation to determine the surgical program.