Square face, commonly known as "big cheeks (bones)"; It is medically called mandibular angle hypertrophy or square face deformity. This kind of face is out of tune with the aesthetics of orientals. Especially women, oriental women advocate oval face or oval face. In addition to the aesthetic standard of "three stops and five eyes" and the golden ratio, the face should also have beautiful curves. The upper part of the face (that is, the width of the temporal bone or the distance between temples), the middle part of the face (the distance between the outer edges of the zygomatic arches on both sides) and the lower part of the face (that is, the distance between the outermost points of the two mandibles) should have a proper proportion and be coordinated with the length of the face.
Maxillary angle hypertrophy is generally bilateral, and unilateral is not uncommon. It is often related to teenagers eating too many snacks and chewing gum (or betel nut) during their physical development, or it may be caused by grinding their teeth at night. All these make the levator palatini muscle group (masseter muscle, medial pterygoid muscle, etc. ) excessive exercise stimulates the development of muscles and bones in the mandibular angle area, and finally presents "square face deformity". Therefore, it can be considered that there are two reasons for mandibular angle hypertrophy: one is mandibular angle bony hypertrophy; Second, the masseter muscle is overdeveloped, with prominent cheeks on both sides. Specific to each patient, the influence of the two reasons may be different, which may be that the bones are dominant or the muscles are dominant.
Understand the etiology and pathogenesis of mandibular angle hypertrophy, and then talk about its treatment. With the development of high technology, human beings can walk into the earth in nature, and they can also "walk through the snow without trace" when treating their own diseases. The operation level of plastic and cosmetic surgeons is constantly improving. Square face surgery, which originally required an incision on the face and neck and left a scar before treatment, has long been able to leave no scar on the patient's body surface in the plastic surgery department of Diaoyutai Hospital. So far, nearly 200 such operations have been performed. Have considerable experience. Our department has changed the old method that it is necessary to cut the skin and muscles near the mandibular margin, leaving a scar 5 cm long, which is easy to damage the mandibular marginal branch of the facial nerve and cause facial paralysis. But from the mucous membrane in the mouth, really leaving no trace.
Surgical methods and clinical data
1. method
(1) Applied Anatomy (1) (2) The mandible is arched and consists of horizontal mandibular body and vertical mandibular branches. The intersection of mandibular body and mandibular branch is called mandibular angle. The lateral side of the mandibular angle is a masseter nodule with masseter muscle attachment. The medial pterygoid muscle is the greater trochanter with the medial pterygoid muscle attached. It is necessary to fully peel off the attachment of mandibular angle tendon during operation. The mandibular angle varies from person to person. The normal angle is 120~. There is no obvious large medullary cavity in the mandible, which is mainly cancellous bone, which can be used as the anatomical basis for mandibular angle thinning surgery.
There is a mandible L in the upper part of the center of mandibular branch. In adults, the hole is approximately equivalent to the plane of mandibular molars, while in women, the hole is lower. There is a mandibular nerve groove behind the mandibular foramen, and the inferior alveolar nerve vascular bundle enters the mandibular foramen through this groove, which is the injection place of the inferior alveolar nerve intraoral block anesthesia. In the anterior lower part of mandibular foramen, there is a mandibular protuberance formed by the confluence of coracoid process and medial condyle. There are buccal nerve, lingual nerve and inferior alveolar nerve. Inject anesthetic into this protrusion and anesthetize these three nerves at the same time, so as to obtain anesthesia of one side of mandible, teeth and oral mucosa.
The mandibular canal is located in the mandible, and the inferior alveolar nerve and vascular bundle enter from the mandibular foramen and exit from the mental foramen. Don't hurt this tube during the osteotomy.
(2) Classification of mandibular angle: According to the appearance and the reference mandibular X-ray film, the mandible can be divided into three types, namely: ① valgus type: (front view) the mandibular angle is obviously outward, and the distance between mandibular angles exceeds the distance between cheekbones (Figure 1). ② Posterior downward protrusion: (side view) The mandibular angle protrudes downward and backward, and the angle is often less than 1 10 (Figures 2 and 3). ③ Compound type: those with the characteristics of the first two (Figures 4 and 5).
(3) Preoperative preparation: ① Take the X-ray films of the frontal and curved sections of the mandible as a reference for mandibular classification and osteotomy. (2) Let the patient face the mirror, cover the lower part to be removed with both hands and palms, analyze the types of mandibular angle hypertrophy with the patient, and the two sides reach an agreement on the surgical plan, including the scope of bone removal, whether to remove masseter muscle or buccal fat pad, etc.
(4) Operation essentials: ① Local nerve block anesthesia: 2% lidocaine and1:200,000 epinephrine are used as anesthetics. Open your mouth wide, behind the molars, and the tip of the buccal fat pad is slightly outside the center of pterygomandibular fissure as the insertion point. Put the syringe between the 1 and the second bicuspid teeth of the opposite mandible, push it forward about 2.5cm, that is, reach the inferior alveolar nerve groove inside the mandibular ramus, and there is no blood withdrawal, then inject the alveolar nerve under the anesthesia of 1.5 ~ 2.0 ml anesthetic, and then retreat the needle to the muscular layer. ② Local infiltration anesthesia: In order to enhance the anesthesia effect, percutaneous needle puncture was performed at the mandibular angle, close to the bone surface, and infiltration anesthesia was performed under the periosteum in the attachment area of masseter and medial pterygoid muscle. ③ Mandibular exposure: an incision was made in the mouth from the lower front edge of mandibular ramus to buccal gingival sulcus to the second bicuspid, reaching the periosteum. Under the periosteum, without exposing the mental nerve, the middle and lower segments of the outer plate of the mandibular ramus and the mandibular body, especially the periosteum of the mandibular margin, mandibular angle and the posterior margin of mandibular angle, should be stripped as completely as possible. ④ Osteotomy: With the help of light guide retractor, the mandibular angle was marked with pencil according to preoperative prediction. Zimmer pneumatic pendulum saw was used, the outer plate of mandibular angle was obliquely cut and turned out, and the outer plate was split and thinned with a bone chisel. For the kyphosis type, the inner and outer plates are cut by arc full thickness, and the mandibular angle is cut off full thickness; For the compound type, the combined osteotomy method of arc full-thickness osteotomy first and then thinning the outer plate was adopted. ⑤ Masseter muscle and buccal fat pad: If masseter muscle is hypertrophy, the posterior inferior masseter muscle should be thinned; For those whose cheeks are too plump, remove the buccal fat pad. ⑥ Post-operative treatment: compression fixation with elastic bandage. Change the elastic jaw support after 5 days, and remove the stitches after 7 days. Follow the clue to 2w.
discuss
1. Since Legg (4) first described masseter hypertrophy in 1880, western scholars have always defined it as benign masseter hypertrophy. Later, it was discovered (3) that the main reason for the wide or square face shape in the lower part of the Oriental is the bone hypertrophy of the mandibular angle rather than the simple masseter hypertrophy. Mandibular angle hypertrophy is a congenital or acquired developmental defect, not a pathological condition. Oriental aesthetic point of view is that melon seeds or ellipsoids can better show women's charm, gentleness and tranquility. Therefore, women often need to change their square faces into oval faces. The proportion of young women aged 20-30 in this group is 85%, which can be explained.
2. Diagnosis and classification of mandibular angle hypertrophy: Because the degree of hypertrophy of square face or mandibular angle is affected by many factors, including the angle of mandibular angle, the angle of opening the two wings of mandibular body, the degree of masseter muscle hypertrophy and even the fullness of cheeks can affect the width of the lower part. At present, there is no unified diagnostic standard for mandibular angle hypertrophy. Someone (3) made statistics on the X-ray lateral films of mandibular angle, and thought that mandibular angle
3. Different osteotomy methods are used to improve the stereoscopic vision of the face: In the past, mandibular angle hypertrophy was mostly achieved by cutting the angle to achieve a smooth and smooth side view, which often caused the frontal view to be "too wide" after operation. According to clinical observation, quite a few people have valgus and hypertrophy of mandibular angle, but the angle is normal or greater than 1 10. This type accounts for 19.8% in this group, and only the outer plate of mandibular angle can be thinned. On the other hand, the mandibular angle has both valgus hypertrophy and sharp angle. This type accounts for 42% in this group. During the operation, arc osteotomy was used to shorten the posterior edge of mandibular branch (lengthen the lateral neck), increase the angle of mandibular angle, and at the same time thin the valgus hypertrophy mandibular outer plate. For patients with bilateral mandibular angle asymmetry, corresponding measures should be taken according to different types of bilateral mandibular angles.
4. According to the classification of mandibular angle, different osteotomy methods can be used. For example, for kyphosis, the inner and outer plates can be cut into an arc as much as possible during osteotomy to minimize the vibration caused by splitting with a bone chisel. For large eversion, it is only necessary to cut the outer plate, and use the characteristics of different hardness between the inner and outer plates and cancellous bone to cut off the outer plate skillfully with a bone chisel. Correct and reasonable use of bone saw and chisel can not only facilitate osteotomy, but also prevent accidental fracture of mandibular body.
5. Comprehensive operation of square face or round face: For patients with hypertrophy of mandibular angle and masseter muscle or round face, part of masseter muscle or buccal fat pad is often removed at the same time, so that the middle and lower parts after operation form a harmonious and beautiful face with natural transition of mandibular angle and slight depression of cheeks.
6. In1948, Adams used an external incision to remove the mandibular angle for the first time. In 195 1, converse changed it into an internal incision (4). After that, angular osteotomy through oral incision became a popular operation, with the advantages of: no skin scar; Completely subperiosteal surgery is unlikely to damage the mandibular marginal branch of facial nerve; The masseter and buccal fat pad can be removed at the same time. However, in the past, mandibular angle surgery through oral incision was mostly performed under general anesthesia (⑸ ⑺ ⑻), which had great risks, great influence on patients' whole body, many complications and slow recovery after operation, and often required anesthesiologists and equipment. This operation is completely performed under local anesthesia. The patient is awake, can cooperate with the doctor, and can feel the tissues outside the anesthesia range of the patient to prevent accidental injury. Due to the addition of adrenaline to the anesthetic, postoperative bleeding is less, swelling is less, and recovery is faster. The disadvantage is that some patients are nervous because of the noise of gas saw and the vibration during osteotomy, which can be relieved by sedatives before operation. Because the patient has been awake, postoperative care is simple, and there are infusion conditions, you can go home and rest after one night of observation. Suitable for outpatient work.