1, the history of dental and maxillofacial deformities (Dento-maxillofacial Deformities) refers to the abnormalities in the volume, morphology, and relationship between the maxilla and mandible and other bones of the craniofacial area caused by abnormal development of the jaws, and the accompanying abnormalities in the dental-dental relationship and the function of the oromandibular system and facial morphology. The broad definition of dental and maxillofacial malformations also includes secondary malformations caused by trauma, tumors, and other factors. Orthognathic Surgery is a new and comprehensive field of study and treatment of dental and maxillofacial malformations, and is also a branch of oral and maxillofacial surgery. Distraction Osteogenesis (DO) is a pioneering theory and technique for the correction of skeletal deformities and the repair of bone defects. It is a surgical technique to lengthen or widen a bone by applying specific traction to a segment of bone that retains its periosteal and soft tissue attachments and blood supply after incision, in order to correct a skeletal deformity or defect. It is also called distraction osteogenesis, bone traction, bone scab traction, bone lengthening, etc. in the literature. At present, the rational application and cooperation of DO technique and orthognathic surgery have brought the surgical treatment of dental and maxillofacial malformations into a new stage of development. The treatment of bony malocclusion through surgery was first reported by the American scholar Hullihen in 1849. In 1957, Obwegeser reported for the first time that the sagittal split ramus of the mandibular branch through the intraoral route (sagittal split ramus In the 1970s, Bell further laid the biological foundation of modern orthognathic surgery, and the research work of Obwegeser and Bell changed the history of orthognathic surgery and guided the development of contemporary orthognathic surgery. Since the 1980s, with the successful clinical application of rigid internal fixation and pre- and post-orthodontic treatment, orthognathic surgery has been perfected and has truly entered a new era of combining function and morphology. In 1905, Codivilla, an Italian orthopedic surgeon, first proposed the idea that bone and its surrounding soft tissues could be lengthened by slow traction. In the 1950s, the Russian orthopedic surgeon Ilizarov applied this technique to the clinic, and through a large number of clinical applications and biological research, he gradually perfected this bone lengthening technique and established a set of traction rules. The study and application of traction osteogenesis in craniomaxillofacial surgery was later, and in 1973, Snyder first reported the application of DO to lengthen the mandible in animals. The real sense of jaw traction technique is now recognized in 1992, when American doctors McCarthy et al. reported a successful case of lengthening the mandibles of four children using DO technique. 1995, McCarth, Wangerin et al. designed intraoral access jaw tractors, which opened a new stage of built-in traction osteogenesis and became a hot spot for oral and maxillofacial surgery and plastic surgery research. Since the late 20th century, DO technique has become a significant new development in the field of craniomaxillofacial plastic and reconstructive surgery, which can be regarded as endogenous bone tissue engineering. Currently, traction osteogenesis has become a promising new field in the treatment of dental and craniomaxillofacial deformities. 2, the concept of comprehensive sequential treatment of dental and maxillofacial malformations Orthognathic surgery is indicated for all kinds of underdeveloped or overdeveloped dental and maxillofacial malformations, including anterior-posterior, vertical, facial asymmetrical malformations and some cumulative dental malformations. The clinical application of traction osteogenesis can cover lengthening of the jaws, increasing the transverse diameter of the jaws, anterior displacement of the maxilla, augmentation of the restored alveolar bone, repair of segmental defects of the jaws, reconstruction of the jaws and temporomandibular joints, and can be combined with orthognathic surgery to treat some complex dental and maxillofacial deformities. Orthognathic surgery combined with orthodontic treatment can treat most of the cases of dental and maxillofacial malformation, and its course is short, basically can solve the problem at one time, the cost is lower, its shortcomings are mainly the surgery is more traumatic. With the development of perioperative dispositions and surgical techniques, instruments and materials, it has now become a relatively safe routine surgery. Traction osteogenesis has advantages that are difficult to replace by traditional orthognathic surgery for the treatment of complex and difficult cases of dental and maxillofacial malformations. The operation is relatively simple, the operation time is short, no donor area surgery is required, the age of surgery can be relaxed to young children, the bone can be lengthened and the soft tissue can be expanded, and the recurrence rate is relatively low. The main disadvantages are the need for second-stage surgery to remove the retractor, the long duration of the procedure, the inability of the child to cooperate with the treatment, and the high cost. It is worth mentioning that although the traction osteogenesis technique has obvious advantages for the correction of severe dental and maxillofacial skeletal deformities, we should keep in mind the importance of both form and function, especially the occlusal relationship, which is difficult to establish precise occlusal function by surgeons alone. This requires us to combine orthodontic and orthognathic surgical techniques, from the development of the treatment plan to the post-operative follow-up. The authors believe that the standardized treatment of dental and maxillofacial malformations should be treated in the same way as other branches of oral and maxillofacial surgery, with a comprehensive sequence of treatment based on specific conditions. In some patients with congenital malformations, such as children with cleft lip and palate, orthodontic appliance treatment can be initiated at the neonatal stage to mitigate the development of nasolabial deformity. For those who are found to have a tendency to develop bony malformations of the teeth and jaws at an early stage, interventional treatment, such as wearing movable orthoses, can be performed during the pre-growth or growth phase, with a view to minimizing the progression of the malformation and reducing the trauma associated with future surgery. Before a patient receives comprehensive treatment, a very critical step is to conduct a consultation and discussion among several related disciplines, combining clinical examination, X-ray cephalometric analysis, model analysis, and computer analysis of predicted results to create an individualized treatment plan for the patient. The purpose of preoperative orthodontic treatment is to align the teeth, coordinate the dental arch, remove compensatory tilt, adjust the occlusal curve, and control the root movement, so as to provide a solid foundation for bone cutting, accurate spelling of the occlusal relationship during surgery, and stable recovery and reconstruction of the occlusion after surgery. Some patients with poor oral hygiene, periodontitis or dental caries may affect orthodontic treatment and postoperative wound healing, and periodontal diseases should be cured or controlled as much as possible before serial treatment. Orthognathic surgical treatment options should be preferred for the vast majority of patients who can be treated with orthognathic surgery as a one-time orthognathic treatment, while traction osteogenesis should only be considered for certain cases where traditional orthognathic surgery is expected to be ineffective or difficult to treat. For example, in cases of small mandibles with OSAHS, where the bimaxillary advancement of traditional orthognathic surgery is limited, traction osteogenesis can be used to adequately advance the jaws and achieve adequate expansion of the upper airway. For some complex and difficult cases, such as cleft lip and palate secondary to maxillary hypoplasia, old traumatic jaw dislocation healing, etc., traction osteogenesis combined with orthognathic surgery can be adopted. For example, if the width of the jaw is narrow, traction surgery can be performed first to expand the dental arch, followed by orthodontic treatment to align the teeth, and then orthognathic surgery to correct the deformed jaw relationship. In cases of asymmetrical deformity secondary to TMJ ankylosis, arthroplasty can be performed first to solve the mouth opening problem, and then traction osteogenesis can be chosen to reconstruct the TMJ. For cases with maxillary jaw plane inclination, Lefort I surgery is needed again to correct the deformity. Postoperatively, due to factors such as myodynamic balance alteration adaptation, the occlusal relationship needs to be further fine-tuned by elastic traction and postoperative orthodontic treatment to finally achieve a good occlusion. For some patients with concomitant soft tissue deformities, it is generally recommended that the second stage of surgery be performed after the correction of the bone tissue deformity. Each patient’s deformity has its own individuality, so only by adopting individualized and comprehensive treatment with multidisciplinary cooperation for different etiologies can we achieve the goal of orthodontic treatment with equal emphasis on appearance and function. 3, the development of new technologies in the contemporary surgical treatment of dental and maxillofacial malformations (1) computer-assisted surgery With the advent of the information age, the prevalence of computers has become a symbol of the fourth industrial revolution, and its cross-pollination with the life sciences has produced computer-assisted surgery (Computer aided surgery, CAS), opening up a new field for the development of surgical technology. The development of medical imaging is the basis of CAS. The rapid development of computer image graphic processing technology has enabled the development of orthognathic surgery to reach a new level. Since the Royal Danish Dental Institute developed the world’s first computer-aided cephalometric system in 1958, this technology has become more and more widely used by orthognathic surgeons with the continuous advancement of digital technology and the development of medical imaging techniques. Compared with traditional manual measurement, computer-aided cephalometric techniques are simple, precise, efficient, accurate, and intuitive in prediction, and very convenient for communication between doctors and patients. However, the problem of fixation still needs to be performed manually and there is a certain amount of human error, and there are already institutions that have studied the development of automatic computer identification for fixation measurement for this problem. In addition, the quality of the image also determines the results of the cephalometric measurement, the traditional X-ray film in the asymmetric deformity of the patient’s frontal morphology measurement error, the emerging digital X-ray technology through the X-ray exposure into optical signals, by the optical fiber through photoelectric coupling into electrical signals, and then converted into thousands of gray-level image signal, its image quality is high, the radiation dose is small, fast imaging, conducive to automatic computer identification The image quality is high, the radiation dose is small, and the imaging is fast, which is conducive to automatic computer identification and analysis. In soft tissue lateral image prediction, after Holdaway proposed the concept of “visual treatment objective” (VTO) in 1971, many scholars devoted themselves to the study of computerized soft tissue prediction systems. However, according to the literature review, the soft tissue prediction system still has the defects of inaccurate prediction, lack of personalized prediction, and large error, so its application has some limitations, but it is believed that as the image technology and computer products are more perfectly combined and developed, the soft tissue prediction system can be used to predict the changes of the patient’s face. However, it is believed that with the perfect combination and development of image technology and computer products, soft tissue prediction systems will be more widely used in clinical practice. Rapid prototyping (RP) is an emerging technology developed in the late 1980s, which refers to the computer-controlled manufacturing of prototypes based on computer-aided design (CAD) models or CT data of objects and computer-aided manufacturing (CAM). manufacturing (CAM) stacked manufacturing prototype. This technology is a major breakthrough in the field of manufacturing technology in the past 20 years, which concentrates on the comprehensive application of technologies in the fields of CAD, laser processing, data and new material development. At present, RP technology has been widely applied to defect repair such as individualized implant pseudo-replication system, as well as preoperative cranial modeling of complex dental and maxillofacial malformations, which has important significance for preoperative diagnosis, design and intraoperative precise guidance of complex and difficult dental and craniomaxillofacial malformations and defects, shortening operation time, and facilitating doctor-patient communication. There are still some problems in the clinical use of RP technology, although its industrial accuracy can reach 0.1mm, but the accuracy in the clinic has been reduced, and there is a certain error in the tooth morphology reproduction and occlusal relationship reconstruction. The future development direction of CAD/CAM technology is: supporting parallel engineering technology and reverse engineering technology, realizing off-site network transmission, supporting on-site construction, realizing virtual design and virtual manufacturing. In recent decades, developed countries in Europe and America have invested heavily in the development of craniomaxillofacial 3D reconstruction and simulation systems, gradually realizing three-dimensional 3D visualization of craniomaxillofacial soft and hard tissues and interactive osteotomy for surgical simulation. The traditional analysis and simulation of orthognathic surgery is carried out on a two-dimensional plane, and due to the complex structure of human craniomaxillofacial, the face is not completely symmetrical, and the problem of overlapping left and right sides in X-ray projection affects the traditional surgical simulation and efficacy prediction. Although model surgery realizes the concept of three-dimensionality, it is difficult to predict the change of soft tissue appearance in three dimensions after surgery because it is detached from the facial soft tissue contour. Therefore, the introduction of computerized 3D visualization surgical simulation and prediction system into the field of orthognathic orthognathic treatment extends the limited vision of surgeons and breaks through the boundaries of traditional surgery, which has important significance for improving surgical precision, reducing trauma, and increasing success rate.Cevidanes et al. reported the application of Cone-beam CT combined with computerized 3D manipulation software to evaluate orthognathic surgery before and after It is believed that the visualized 3D model can clearly show the morphology of the condylar process and allow for a directed and quantitative study of the change in condylar position. However, these surgical 3D surgical simulation systems are expensive in equipment, unportable, and the purchase of software cannot be further developed, so some domestic scholars have independently developed a 3D orthognathic surgical simulation system on PC, which has the superiority of convenience, popularity, and flexibility. Some scholars have also published reports on the successful production of a positioned dental cementation plate based on 3D simulation of orthognathic surgery combined with rapid prototyping technology, which avoids the tedious process of manual production of traditional model surgery and improves work efficiency and surgical accuracy. In the context of the continuous development of CAS technology (imal invasive surgery, MIS), the concept of navigation surgery (3D navigation) was introduced into the field of oral and maxillofacial surgery with the help of spatial positioning navigation system to achieve real-time intraoperative 3D visualization and positioning, which opened up a brand new idea for surgical techniques to become more refined and minimally invasive. Navigation surgery was first used in the field of neurosurgery and orthopedics. The application in the field of oral and maxillofacial surgery is mainly focused on oral implants and surgical correction of craniomaxillofacial deformities. The basic components are virtual reality (VR) and positioning tracking system. VR technology refers to a human-controlled three-dimensional image interface, which can quickly modify and control the data collected by other imaging devices, and calculate, display, reconstruct and transmit virtual images, so that surgeons can apply realistic three-dimensional images to observe the human anatomy from any angle and qualify lesions. This allows the surgeon to apply realistic 3D images to observe the human anatomy from any angle, analyze the lesion qualitatively and quantitatively, and simulate and guide the surgery. In patients with severe dental and maxillofacial combined craniomaxillofacial deformities, the bony three-dimensional spatial relationships are complex, and the application of traditional two-dimensional evaluation tools for such deformities is significantly limited. Therefore, the introduction of 3D spatial technology has brought a boon to improve the preoperative design and outcome for such patients. The trend in oral and maxillofacial navigational surgery lies in the further development of VR technology and the improvement of simulated surgical teaching and training systems. Combined with medical robots and remote control surgery (telesurgery), the development of telemedicine systems establishes the basis for precise, minimally invasive and humanized surgical treatment. (2) Minimally invasive surgery concept Minimal invasive surgery (MIS) and the trend of minimally invasive surgery has become the trend of surgery in the 21st century. 1983 British urologist Wickham first proposed the concept of modern minimally invasive surgery, mainly refers to the use of endoscopic surgery instead of traditional surgery, with the help of specialized instruments using small incisions and small trauma surgical treatment. In 1983, Wickham, a British urologist, first introduced the concept of modern minimally invasive surgery. The concept of minimally invasive surgery was first introduced by Dr. Wickham, a modern surgeon. Since the early 1990s, with the widespread application of electronic devices in endoscopic technology, laparoscopy, hysteroscopy, arthroscopy as a representative involving almost all clinical surgical departments laparoscopy exhibition rapidly, sets of special equipment:. At present, endoscopy in general surgery, obstetrics and gynecology, urology clinical applications are most popular. With the continuous development of oral and maxillofacial surgery, minimally invasive surgery has been applied to the diagnosis and treatment of some common clinical diseases in recent years, in temporomandibular joint surgery, craniofacial trauma, salivary gland diseases, cosmetic surgery and other fields have achieved certain results. In the field of orthognathic surgery, some foreign related animal experiments and clinical reports have been seen in recent years, introducing the concept of minimally invasive surgery into the surgical treatment of various congenital and acquired craniomaxillofacial deformities. Rohner et al. reported Le Fort I osteotomy performed on six human cranial specimens with the aid of endoscopic techniques, and minimally invasive Le Fort I osteotomy was performed on two patients with cleft lip and palate secondary to maxillary hypoplasia, respectively.Sakai et al. suggested that endoscopic osteotomy of the pterygomaxillary junction is very safe with less than 50 ml of bleeding.Troulis et al. chose a small porcine Endoscopic-assisted vertical mandibular osteotomy with strong internal fixation was performed in several patients with mandibular deformities. Wiltfang et al. published a paper on the success of minimally invasive surgically assisted rapid maxillary arch expansion, and Levine et al. reported an experimental animal study of Lefort III osteotomy with a small incision and external traction osteogenesis in the midface. To summarize the literature, the combination of minimally invasive surgical techniques into orthognathic surgery and traction osteogenesis can clearly display the craniofacial anatomy, provide a clear view, protect important anatomical structures such as the facial nerve, inferior alveolar nerve, and internal maxillary artery, with hidden scars, smaller surgical dissection, less bleeding, accurate bone repositioning, fewer postoperative complications, early functional exercise, and help reduce patient pain It has obvious advantages of speeding up postoperative recovery and shortening hospitalization time. However, the requirements of minimally invasive surgery are very high for equipment and instruments, and due to the limitation of incision and instruments, the operation area is limited, and some complex surgical operations can only be completed by traditional “open” surgery. There is less research on minimally invasive orthognathic surgery and traction osteogenesis at home and abroad, probably because most of the traditional orthognathic surgical operations can be performed intraorally and the surgical operations are not complicated, so the advantages of minimally invasive technology are difficult to manifest for a while, so the clinical application is still relatively limited. But I believe that with the continuous development of computer technology, navigation surgery technology, micro-robot-assisted surgery, surgical instruments, minimally invasive orthognathic surgery and traction osteogenesis technology will have considerable room for development. (3) Resorbable materials Since the 1960s, foreign countries have been studying resorbable internal fixation materials. Since Cutright et al. used poly-L-lactic acid material for internal fixation of macaque mandibles in 1971, the development of resorbable materials in the field of oral and maxillofacial surgery has attracted increasing attention, and Haers et al. reported the application of SR-PDLLA material for orthognathic surgery to treat An’s Haers et al. reported that the application of SR-PDLLA material for orthognathic surgery for the treatment of An’s Class II and III malocclusion and chinplasty achieved results comparable to those of traditional metal titanium plates. The biodegradable material is a synthetic polymeric organic material or natural polymeric material, which is hydrolyzed and oxidized in the body, and the end products are CO2 and H2O, which are excreted through the respiratory and urinary system and do not accumulate in the body, so the absorbable material has almost no toxic side effects on the human body and does not require secondary surgery. Compared with traditional metal internal fixation material, it has the advantages of lower or no stress shielding effect, no corrosion effect, no interference with radiological images, etc. The commonly used resorbable materials are polyglycolic acid (PGA), polyglycolic acid (PGA), and polypropylene glycolic acid (PGA), which have no effect on the collection of hel Maxillofacial Surg, 1971,29:393. polyactic acid [J]. (poly lactic acid, PLA), polyamide, and self-reinforced PGA (SR-PGA), etc. Natural polymeric biomaterials, such as chitin, have a series of biological activities such as anti-microbial, anti-tumor, anti-coagulant activity, immune enhancement, and promotion of tissue repair, etc. With the continuous development and research in recent years, it is expected to be gradually applied as a new absorbable material in clinical practice. The shortcoming of resorbable material is its insufficient mechanical strength, especially with the in vivo degradation reaction its strength decreases and decays faster, sometimes it can not meet the requirements of internal fixation when the bone is not yet healed, and there are also reports of local non-specific inflammation. Therefore, although resorbable materials have the advantages of metallic materials that cannot be replaced, they still need to be continuously developed to meet the needs of clinical popularization. The main research directions and development trends are: to further study the compatibility, strength, degradation rate and mechanisms of resorbable materials in different environments; to further improve the mechanical strength of materials, especially resorbable screws; to develop retractors made of resorbable materials; to reduce, avoid and prevent the incidence of delayed aseptic inflammatory reactions; to combine different growth factors with materials to make resorbable materials as The combination of different growth factors with materials, so that the resorbable materials as carriers and controlled release systems have both osteoconductive and osteoinductive bioactivities; and the development of localized products. (4) Personalized design Dental and maxillofacial malformations are complex, multidisciplinary and comprehensive diseases. As mentioned above, the treatment plan for patients with dental and maxillofacial malformations should be a comprehensive sequence of individualized design for each case of malformation. For a difficult case, we can apply CAD/CAM combined with RP technology to create a cranial model, and at the same time combine it with a computerized 3D simulation and prediction system for diagnosis, analysis, protocol design and efficacy prediction, in order to achieve the most suitable treatment effect for the individual patient. The development of individualized retractors is also a research direction. For some complex cases, traditional DO may require multiple surgical treatments, such as attempts to design individualized retractors, such as retractors for larger defect ranges with curvature, multi-directional all-in-one retractors, and integrated retractors for traction combined with dental implants, in order to avoid multiple surgeries and shorten the treatment course. In addition, bone-supported maxillary arch expanders and various alveolar bone retractors of different designs are also hot spots for clinical research. It is believed that with the continuous development of computer technology, material science and other emerging technologies, accurate preoperative simulation and prediction systems, navigation surgery, high-performance biodegradable materials, and minimally invasive surgical concepts will bring the surgical treatment of dental and maxillofacial malformations into a new era.