The repair and reconstruction of deformities and defects in oral and maxillofacial surgery involves several diseases and subspecialties, such as repair and reconstruction of congenital facial cleft deformities, repair and reconstruction of postoperative head and neck tumor defects, repair and reconstruction of deformities and defects of maxillofacial trauma, temporomandibular joint, tumor trauma ankylosis, etc. [7]. Zhang Lei, Department of Maxillofacial Surgery, Peking University Hospital of Stomatology The common problems of common repair methods such as vascularized tissue grafting, bone traction osteogenesis, and arthroplasty techniques are limited operative field, the need to rely on the operator’s experience, unpredictable postoperative results, and poor aesthetic recovery. However, navigation technology can play its own unique advantage for maxillofacial repair and reconstruction, especially the reconstruction of complex structures, which is incomparable with other methods. The application of surgical navigation technology in maxillofacial restoration and reconstruction is mainly in the following aspects: 1. Accurate diagnosis and treatment design before restoration Because of the complex anatomical relationship between oral and maxillofacial, it is difficult to determine the site and scope of the jaw lesion through a plane figure, using digital model surgery technology can provide doctors with a three-dimensional model, which can intuitively diagnose jaw diseases and develop surgical plans, thus avoiding Damage to important anatomical structures. The use of the mirror inversion technique allows the reconstruction of the missing bone on the affected side from the information of the healthy side, and the design and fabrication of a personalized restoration symmetrical to the healthy side to solve the problem of craniomaxillofacial symmetry (mostly used for the repair of deficient deformities of the upper and lower jaws, zygomatic bone and orbital area) [8]. Rapid prototyping technology can also be combined with implant prosthetics to design implant stumps on the defective mandibular personalized restorations and complete the overall reconstruction of form and function through second-stage implant restoration to improve the quality of life of patients [9]. 3. Surgical simulation (1) Computer-aided simulation Surgical design such as bone tumor boundary judgment, surgical osteotomy line, joint repositioning, bone reconstruction and restoration method selection in the simulation environment, and reflect the data of surgical operation to the real surgery in the form of template. (2) Model surgery simulation Using the surgical template and skull simulation model as the guide, the same surgical instruments as the actual surgery are used to determine the position of osteotomy, bone graft movement, bone plate shaping and personalized prosthesis implantation, simulating the operation of osteotomy, movement and fixation, which can guide the real surgery operation. If difficulties are found in the operation, the surgical plan can be further modified to increase the operability of the surgical plan and improve the surgical plan. 4. Postoperative evaluation of surgical results The surgical results can be objectively evaluated by automatic image fusion of preoperative and postoperative CT information and calculation of the gap between the postoperative and preoperative design of the repair position [10]. In terms of application areas, the current application of surgical navigation technology is mainly in the following areas 1. orbital and mid-facial defect reconstruction The most common undesirable restorative consequence of traditional restorative methods is intraocular invagination, which subsequently leads to limited ocular mobility and diplopia. The navigation system, with its unique advantages, allows reconstruction of unilateral defects in the orbital area and midface by means of the mirror inversion technique; for bilateral defects, reconstruction is performed according to the existing database and the intact bone structure, which greatly improves the function and aesthetics of the repair; avoiding damage to important structures. Postoperative complications are rare [11], [12]. 2. Zygomatic bone repair and reconstruction Conventional repair methods often require large incisions in order to expose the zygomatic bone and have poor postoperative aesthetics. Surgical navigation techniques allow for a reduced incision for zygomatic bone repair, and the procedure can be completed without complete exposure of the zygomatic bone [13], [14], [15]. 3. Maxillary defects For maxillary defects, the use of navigation technology allows better shaping of the graft, accurate positioning of the graft intraoperatively, and good restoration of the occlusal relationship, which facilitates subsequent implantation [16]. For large mandibular defects, especially those involving curved areas, it takes a lot of time to shape the graft bone during surgery. The use of rapid shaping and inverse seeking techniques to establish the shape and functional reconstruction of large mandibular defects allows precise fabrication of the replacement, smooth intraoperative seating, firm fixation, minimal bleeding, short operative time, and good wound healing. After the surgery, the facial shape was satisfactorily restored, the mouth opening was improved, and the occlusal relationship was good. On the basis of this, the second-stage implant was performed and the masticatory function was well restored [9]. Some scholars also believe that the restoration of large scale mandibular defects with pure titanium restorations may have difficulties in the placement of second-stage implants and unsatisfactory recovery of masticatory function, as well as problems of prosthetic rejection. Instead, model surgery was performed on a 3D cranial model, prefabricated personalized mandibular medical titanium plates, and vascularized autogenous fibula grafts were applied to repair mandibular defects with good postoperative mandibular shape recovery [17]. Real-time surgical navigation is not commonly used in mandibular repair and reconstruction, mainly related to the fact that the mandible is a movable structure. There are three main possible methods to solve this problem: first, to fix the upper and lower jaws before CT is performed; second, to keep the mandible in a median relational position or median symphysis, thus maintaining it in a relatively stable position; and third, to fix the positioning structure directly to the mandible, making it a relatively fixed structure [16]. It has not been widely used in clinical practice because of the possibility of interfering with the surgical operation and the instability of the relative position. However, recently, a special splint with internal positioning points has been reported, which can maintain the relative position of the jaws and have a certain degree of opening, and can be removed intraoperatively to facilitate surgery, and then put back into the mouth when needed to reproduce the previous navigation information, with more satisfactory clinical results [18]. 4. Second-stage repair of maxillofacial defects It is common to see patients who need second-stage repair due to untimely consultation or treatment needs, or unsatisfactory first-stage repair. In this case, the difficulty of repair is greatly increased because of the alteration of normal anatomical landmarks caused by bone remodeling and the poor visual field. In contrast, the application of surgical navigation technology has opened up the surgeon’s field of vision, and the position of the bone segment is monitored in real time intraoperatively to guide the surgery [19]. The application of surgical navigation system-guided traction osteogenesis in oral and maxillofacial traction firstly, the cranial positioning frontal and lateral radiographs are scanned into the system, at least seven reference marker points are identified, and the surgical positioning of these seven marker points is required to be exactly the same as the radiograph positioning, and the fixed segment and the traction segment are connected to two sensing positioners respectively, and the traction bone can be monitored in real time on the computer screen X-ray through electromagnetic or optical tracking system. The three-dimensional movement of the traction segment can be monitored in real time on the computer screen X-ray film by means of an electromagnetic or optical tracking system, so that the optimal traction vector can be adjusted and selected in time during and after surgery to ensure the postoperative traction effect [20].