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Since 1980s, standard bimaxillary surgery, rigid internal fixation, preoperative and postoperative orthodontic treatment (preoperative and postoperative).

The successful application of orthodontic treatment marks the maturity of orthognathic surgery. Most dentofacial deformities can be corrected by comprehensive application of these three techniques.

Indications of orthognathic surgery

Orthognathic surgery has been widely used to correct various dentofacial deformities, even many craniomaxillofacial deformities. Common dentofacial deformities are:

Dentofacial deformities involving jaws;

① Anterior and posterior deformities, such as maxillary protrusion, maxillary retraction, mandibular protrusion, mandibular retraction, bimaxillary protrusion, maxillary protrusion with mandibular retraction, maxillary retraction with mandibular protrusion, mandibular protrusion and mandibular retraction, etc.

② Vertical deformities, such as long face syndrome and short face syndrome.

③ Facial-jaw asymmetry, such as hemifacial short stature, unilateral condylar dysplasia and unilateral ankylosis. The asymmetry deformity caused by the overgrowth of the half jaw includes the overgrowth of unilateral condyle and neck, and chondroma first shows obvious facial asymmetry.

Deformities involving dentition:

① Anterior malocclusion

② Open jaw deformity

③ Orthodontic treatment should be the first choice for the locking and opening of posterior teeth, which only involves dentition deformity.

Standard bimaxillary surgery

Maxillary LeFort I osteotomy;

LeFort I osteotomy is a large-scale operation in oral and maxillofacial surgery, and avoiding massive bleeding or even life-threatening serious bleeding during the operation is the key to the safe implementation of the operation. First of all, the operation should be performed through nasotracheal intubation under general anesthesia. In addition, controlled hypotension should be used during anesthesia. Controlling systolic blood pressure at about 90 mm Hg can often reduce blood volume by more than 50%. The connection between maxilla and broken wing is a very important surgical step in modern LeFort I osteotomy (including maxillary descending fracture). Because the pterygopalatine junction is the pterygopalatine tube, which contains the internal maxillary artery, the internal maxillary artery may be damaged regardless of improper osteotomy position or wrong chisel position and direction. Our department adopts the method of digging out the double maxillary nodules, which greatly reduces the risk of injuring the internal maxillary artery.

Sagittal split osteotomy of mandibular branch (SSRO);

In 1960s and 1970s, sagittal split osteotomy of mandibular ramus was once daunting and rarely used because of its frequent complications and even life-threatening. Since 1990s, with the wide application of rigid internal fixation technology, this operation has become the most commonly used method to correct mandibular deformity.

Horizontal osteotomy and chin plasty;

Horizontal osteotomy chin plasty is an auxiliary operation combined with LeFort I osteotomy and SSRO operation, and its purpose is to create a harmonious and symmetrical facial structure. We should attach great importance to preventing the soft tissue injury at the floor of mouth or around jaw from forming hematoma at the floor of mouth or even suffocation. In a word, LeFort I osteotomy, SSRO operation and horizontal osteotomy chin plasty are the most commonly used operations in orthognathic surgery.

Jaw distraction osteogenesis

As early as 1905, the Italian scholar Codivilla had successfully tried to lengthen the long bone (femur) of limbs, but it became a clinical technology that could be successfully applied, but it was attributed to a large number of experiments and clinical research work carried out by the Russian scholar Ilizarov in the 1950s. The earliest documented mandibular distraction osteogenesis was completed by Dr. Rosenthal in 1927, which was a case of correcting micrognathia with an intraoral spring traction device supported by teeth. 1973, American scholar Snyder conducted an experimental study on mandibular distraction osteogenesis in a dog's mandible, and successfully made the dog's mandible distraction osteogenesis 15 mm new bone. However, the clinical application of mandibular distraction osteogenesis in the true sense has been generally recognized, starting from 1992, when American scholar McCarthy first reported that 4 children used external distractor. From 65438 to 0995, McCarthy and Wangerin successively designed a jaw distractor that could be placed through the oral cavity, thus opening a new stage of distraction osteogenesis in the jaw. Since then, the built-in distraction osteogenesis technology has quickly become the research focus of international oral and maxillofacial surgery and plastic surgery. It is considered as a landmark new progress in the field of oral and maxillofacial surgery in the 20th century.

Basic principle of distraction osteogenesis

Gradually applying traction to living tissues can make them produce tension, thus stimulating and maintaining the regeneration and growth of these living tissues. Yili Sarow called it the law of tensile stress. Under the slow and steady traction, the body tissue becomes a state with metabolic activity, which is characterized by the proliferation and activation of cell biosynthesis function. Its regeneration process depends on the appropriate blood supply and the size of the stimulus.

Clinical application of distraction osteogenesis of jaw

Maxillofacial distraction osteogenesis is mainly applied to various types of hypoplasia and bone defect deformity involving maxilla. Such as micrognathia, hemifacial hypoplasia syndrome, Nager, Crouzen, Robin, Treasurer Collins syndrome, etc.

1. Micromandibular deformity

Severe micrognathia caused by various reasons, such as TMJ ankylosis, is the best indication for correction by this technique. The mandible can be lengthened by more than 20 mm, which can not only effectively correct the serious dentofacial deformities of such patients, but also have a very good therapeutic effect on their accompanying obstructive sleep apnea syndrome (OSAS).

2. Hemifacial hypoplasia syndrome

Hemifacial hypoplasia syndrome is a difficult problem in clinical correction in the past. The correction of jaw deformity is not only limited by the bone condition itself, but also the accompanying soft tissue hypoplasia makes the operation more difficult, and the conventional operation is not effective and easy to recur after operation. In the past, the correction of this deformity generally needed to wait until the patient stopped developing. This also has a negative impact on the psychological development of patients. Early distraction osteogenesis will undoubtedly greatly reduce the degree of deformity and benefit the psychological development of patients. At the same time, it will create better conditions for further correction in adulthood.

3. Severe stenosis of maxillary and mandibular dental arch.

Severe maxillary arch stenosis often leads to severe crowding of dentition, which is characterized by serious disharmony between tooth quantity and bone quantity. In the past, the correction of this kind of deformity mainly relied on orthodontic arch expansion technology and meiotic tooth extraction to achieve the purpose of aligning dentition. The application of distraction osteogenesis in maxillary and mandibular dental arch expansion not only avoids the inclined movement of teeth with high recurrence rate, but also realizes the real increase of dental arch bone mass and rapid arch expansion. Severe dentition crowding can be corrected without tooth extraction.

4. Distraction osteogenic reconstruction of mandibular defects and defects.

Based on Ilizarov's "double focus" and "triple focus" distraction osteogenesis principle, partial mandibular loss caused by tumor resection or trauma was successfully applied in clinic. Firstly, one or two transport trays with a length of about 65438±0.5cm are formed on one side or both sides of the mandibular bone defect, which are continuously moved to one end or center of the defect under the action of a bifocal or trifocal distractor, and finally the bone space is pulled under pressure to heal with the opposite bone segment to form new bone, so as to achieve the purpose of reconstructing the mandibular bone defect without bone grafting.

5. Vertical distraction osteogenesis of alveolar bone loss

In the past, severe alveolar bone resorption and atrophy could only be reconstructed by bone grafting. Especially for patients with severe alveolar bone resorption, atrophy and loss, it has become a clinical problem to implant and repair dentition loss, how to reconstruct the missing alveolar bone and restore the vertical height of alveolar bone. The appearance of vertical traction provides a simple and effective new means to solve this problem. In recent years, there have been a large number of reports of successful traction of atrophic alveolar bone in bed, and successful vertical traction osteogenesis on reconstructed fibula flap to meet the needs of implant repair.

6. distraction osteogenesis of maxillary hypoplasia

Maxillary dysplasia is the main clinical symptom of many craniofacial dysplasia syndromes. Patients with cleft lip and palate often suffer from severe maxillary hypoplasia. Because of the limitation of jaw movement, the traditional orthognathic surgery to correct this deformity is usually unsatisfactory. Moreover, on the one hand, a large number of bone grafts are needed after moving the jaw greatly, on the other hand, the postoperative recurrence rate is high. Maxillary distraction osteogenesis with built-in or extracranial fixed distractor can move the maxilla forward more than 65438±05mm, which provides a new means for the correction of this kind of patients. In recent years, the extracranial fixed tractor has provided convenience for children's application because of its advantages such as good stability, small traction range and convenient disassembly.

7. Reconstruction of temporomandibular joint ankylosis by distraction osteogenesis.

The treatment of temporomandibular joint ankylosis has always been a major clinical problem. It not only affects a series of physiological functions of patients' oral and maxillofacial system, but also is often accompanied by severe dentofacial deformities, and many patients are accompanied by OSAS in different degrees. 1997 McCormick reported that the treatment of temporomandibular joint ankylosis with external traction device was successful. Its advantages are: ① it can effectively restore the height of the ascending branch of the affected side. Conducive to the correction of facial deformity of patients. ② Compulsory open training can be started 2 ~ 3 days after operation, so the recurrence rate is low. 65438-0998 Orthognathic Surgery Center of Peking University Stomatological College used built-in jaw distractor to treat temporomandibular joint ankylosis, and achieved very satisfactory results.

Advantages and disadvantages of orthognathic surgery and distraction osteogenesis and their choice

Distraction osteogenesis and orthognathic surgery have their own advantages and disadvantages. As far as orthognathic surgery is concerned, although the operation is traumatic and risky, for most patients with dentofacial deformities, it is possible to obtain good correction results in one operation. Therefore, the short treatment time and relatively low cost are undoubtedly its advantages. What's more, many dysplasia-like deformities do not need to increase the amount of soft and hard tissues, and there is no room for distraction osteogenesis in the treatment of such deformities. Jaw distraction osteogenesis does provide a new and effective method for the correction of jaw dysplasia or tissue loss, but these deformities can not be corrected by orthognathic surgery or even if complex orthognathic surgery combination is adopted, the correction effect is still not good. However, distraction osteogenesis requires two operations (the first osteotomy, placing the tractor, and taking out the tractor for the second time), and traction devices are needed. After placing the distractor, there are still intermittent, traction and stable periods in clinic (generally 3-4 months for mandible and 4-6 months for maxilla). This makes it have the disadvantages of long course of treatment and high cost. Therefore, we advocate that orthognathic surgery is the first choice for patients with dentofacial deformities if they can be treated once. The decision to use distraction osteogenesis for patients must be aimed at patients who are difficult to correct or have poor correction effect in orthognathic surgery.