Posterior maxillary osteotomy

The posterior maxillary osteotomy is used for surgical correction of maxillary deformity. If the maxillary deformity is not involved in the entire maxilla, such as only the posterior maxillary (unilateral or bilateral) vertical over-long deformity, this operation can be corrected. Based on this procedure, appropriate changes can be used to correct other types of maxillary posterior deformities, such as: after the osteotomy of the maxilla, and torsion to correct the buccal or temporal side of the posterior maxillary Malformation and so on. Treatment of diseases: maxillary protrusion Indication The posterior maxillary osteotomy is suitable for vertical over-long deformity of the maxilla (eg, anterior open deformity), but the rest of the maxilla is normal. Contraindications The anterior open deformity is caused by the vertical dysplasia of the anterior maxilla. Preoperative preparation Prepare for orthognathic surgery. There are many types of dental malformations, and the situation is different. The deformity may be simple or complicated. Patients often have a variety of mental and psychological states. Therefore, there are many factors to consider before surgery, and various preparations should be made according to the specific situation. 1. As with general surgery, detailed medical history enquiries, records, and comprehensive physical examinations are required before orthognathic surgery, including: general and partial examinations. The whole body examination focuses on the situation of important organs. Local examinations include facial examinations, oral and dental model examinations, and X-ray examinations (cephalometric measurements, full-mouth curved torsions, and dental fragments). Based on the above results, a definitive diagnosis is made and a question table is listed as a basis for developing a treatment plan. The final treatment plan should be able to solve all or most of the problems listed in the table. 2. Determining the preoperative prediction of the therapeutic effect before performing orthognathic surgery. The most common methods are: photo cutting and pairing, cephalometric X-ray film tracing, cutting and cutting (paper-cut surgery) and dental model surgery. The latter two are more important. Through the preoperative prediction, comprehensively judge the effect of the design surgery, and if necessary, make corrections. In recent years, scholars have used computers, graphic digitizers, cameras, scanners, etc. to acquire and input images, and perform fixed-point, measurement, analysis, and surgical simulations to predict postoperative morphology of the patient's side. Recently, computer-aided three-dimensional surgical design simulation systems and computer-aided three-dimensional skull models have been established to create more precise conditions for the design and prediction of orthognathic surgery. (1) Cephalometric Prediction Tracing with Cutting and Piecing together: cephalometric measurement, cutting, or cutting. It is an important means of preoperative prediction of orthognathic surgery. The specific method is as follows. 1 Place the cephalometric X-ray film on the viewing box (or the viewing light) and draw the two trajectories in the transparent tracing paper. 2 Take a well-drawn trajectory map and cut the bone segment ready for osteotomy and movement. For example, this example is intended to be a maxillary LeFortI osteotomy and upward movement. 3 Place the cut piece of paper (such as the maxilla in this case) on another complete trajectory map so that it is in the desired position of movement (as in this case, up). 4 Place the remaining part of the jaw of the first trajectory (such as the remaining mandible in this case) on the complete trajectory to fit the piece of paper that moves the bone. This is the expected general position of the jaw after orthognathic surgery. 5 Then draw a soft tissue outline on the outer circumference of the bone to obtain a general outline of the postoperative shape. This is one of the main references for predicting the outcome of surgery. (2) Model Surgery: referred to as model surgery. On the tooth model (usually on the shelf), simulate the design of the operation, saw the model, and move the block in the desired position, fixed with sticky wax. Observe and measure the changes of the model to judge and predict the effect of the operation. It is a three-dimensional template, and the paper-cutting surgery is a three-dimensional simulation. One of the commonly used preoperative prediction methods. 1 First take the mold, pour out the tooth model, and transfer the to the shelf through the facial arch to obtain the relationship between the mouth and fix it. And draw a horizontal and vertical reference baseline on the model. 2 If necessary, draw a longitudinal baseline in the medial side of the temporal side; between the canines to the canines, between the first molars and the first molars, cross the ankles as a baseline. 3 Remove the single jaw model, and use the model saw to saw the tooth model according to the surgical design and divide it into several pieces (such as the maxillary segmental osteotomy in this case). 4 On the mandible model on the rack, place the cut tooth model blocks in the desired position. 5 After each model is in place, the model blocks are connected by sticky wax and fixed on the frame, which is the postoperative condition. Observe the original baseline position on the model, measure and calculate the distance after the movement, which can be used as a reference for surgical design. 3. For patients with major orthodontic surgery requiring orthognathic surgery, it is often necessary to combine preoperative and postoperative orthodontic treatment to achieve the desired results. The main contents of preoperative orthodontic treatment include: correcting a few misplaced teeth, removing interference or blocking, aligning the dentition, adjusting the shape or width of the dental arch, and coordinating the upper and lower dental arches so that the upper and lower dentition can obtain a wide occlusion during the operation. Contact relationship; it is also important to remove the compensation of the teeth and adjust the inclination of the teeth so that the bone segments can be moved to the desired position after the osteotomy. 4. When the surgical plan is determined, a occlusal guide (ply plate) should be made on the model that has completed the model surgery. If you are preparing for the simultaneous osteotomy of the upper and lower jaws, it is often necessary to make two occlusal guides. One is a transitional (intermediate) occlusal guide; the other is a maintenance occlusal guide (final guide), that is, the guide is finally worn during the operation to maintain the ideal position of the upper and lower jaws, and then fixed between the jaws. 5. Prepare the fixation device for the bone segment several days before surgery (such as dental arch splint, adhesive bracket or external fixation device). 6. Do oral care, treat dental disease, and cure if necessary. 7. Prepare for general anesthesia and prepare for general anesthesia. It is estimated that blood transfusion is required, and blood is reserved. 8. Finally, there is an important point in preparing the patient's mind and conducting the necessary psychological counseling. All the designs and the results obtained at the end should be told to the patient in detail, and their opinions should be solicited so that the doctor and the patient can find the unity of both the subjective and the objective. In this way, it is possible to obtain the patient's postoperative cooperation and achieve the desired effect, and finally obtain a satisfactory postoperative effect. Otherwise, subjective and objective inconsistency, although the expected surgical results have been achieved, still can not meet the patient's excessively high non-conformity requirements, backfired. Surgical procedure Incision The vestibular groove of the upper jaw is revealed by a hook. A transverse incision is made from the cuspid to the vestibular groove of the second molar, reaching the bone surface. Separation under the periosteum with a periosteal separator reveals the lateral aspect of the maxilla. Note that the soft tissue under the incision (near the gums) should not be excessively separated to preserve the soft tissue and maintain blood supply. Separation range: sneak back to the periosteum until the maxillary suture; in the front, in the area of the vertical osteotomy line, also for subperiosteal sneak separation. 2. Transverse truncation of the posterior buccal side of the maxilla After exposing the lateral aspect of the maxilla, a transverse osteotomy of the posterior part of the maxilla can be performed. At the height of 4 to 5 mm above the apex of each maxilla, the transverse osteotomy line is marked. In the front of the maxillary posterior vertical osteotomy If one premolar is to be removed, a vertical osteotomy is performed in the extraction space; if no tooth extraction is required, a vertical osteotomy of the bone segment is made between the canine and the first premolar or the first and second premolars. In the apex and premolar area, the soft tissue is pulled down with a small hook, and the bone is cut under the periosteum with a split drill or a thin bone knife, including the temporal bone plate. Be careful not to punch through, damage the periosteum of the temporal side, and place the left finger on the temporal side to feel the osteotomy. 4. Cut off the temporal bone plate A thin bone knife (usually an arc-shaped bone knife) is inserted into the gap of the broken bone line that has been cut off from the buccal side, and the lateral bone plate is gently cut off. The finger can also be placed on the side of the jaw to feel the osteotomy and prevent injury. Soft tissue on the temporal side. It is also possible to use a split or round drill (if the gap of the buccal bone cut line is wide) to complete the lateral cut of the temporal side. 5. Disconnect the posterior part of the maxilla from the wing Behind the maxillary nodules, a thin curved osteotome is inserted from the incision through the periosteum to the pterygoid suture, and is inserted in the inward direction to break the upper jaw nodule from the wing. At this time, the direction of the chisel should be controlled to keep inward, but avoiding upward and backward chiseling, especially to prevent upward force. 6. Broken the upper part of the maxilla and trim the bone After the osteotomy line is completed, the thumb is placed on the bone surface of the posterior part of the maxilla (avoiding only on the teeth) and the lower part of the maxilla is fractured downward with a downward force. Trimming and removing excess bone can often be done with a round diamond or a grinding head. 7. Place the posterior part of the maxilla in place and fix it Preoperative pre-made occlusal guides are used to guide the truncated bone segments in place. Wear the occlusal guide on the lower jaw and move the posterior segment of the maxilla to engage the occlusal guide in a consistent position. Drill holes on both sides (upper and lower sides) of the transverse osteotomy line, through the wire, for inter-bone ligation to fix the bone segment. It can also be used as the humerus suspension of the dental arch splint. And supplemented by intermaxillary fixation. 8. Suture incision The vestibular groove mucosal wound was sutured intermittently. complication See the main complications of orthognathic surgery. Orthognathic surgery may have complications during and after surgery. The surgeon should perform the operation in a serious and responsible spirit, abide by the surgical requirements, operate correctly, carefully and carefully, observe the condition closely after the operation, and timely handle the abnormal situation to prevent various complications. Airway obstruction Acute obstruction of the respiratory tract and even suffocation are the most serious complications. During general anesthesia, due to vomiting aspiration, secretion obstruction, improper position, tongue fall, tracheal edema after tracheal intubation, and subsequent local tissue edema, plus intermaxillary fixation and other factors may cause respiratory obstruction. Measures should be taken to prevent it from happening. Close observation of the condition and elimination of factors that may cause acute obstruction of the respiratory tract. If signs of dyspnea appear (such as nasal agitation, three concave signs, etc.), it should be treated in time to prevent the occurrence of asphyxiating complications. 2. Bleeding Intraoperative injury to larger blood vessels can cause more serious bleeding, such as the maxillary LeFortI osteotomy when the internal maxillary artery or the aorta is injured, and the mandibular ascending branch is used to damage the inferior alveolar artery. Therefore, in the LeFortI type osteotomy, the osteotome can not be placed too high during the process of breaking off the distal end of the maxilla and the wing, and the direction of the incision cannot be upward to prevent damage to the internal artery of the jaw. When cutting the inner wall of the maxillary sinus, care should be taken to avoid damage to the aorta near the posterior end. It is often possible to use a bone knife to cut the bone and not to reach the trailing edge while retaining part of the bone to avoid accidental injury to the aorta. After the maxilla is broken down by the technique and the instrument, the posterior bone is trimmed. When the mandibular ascending branch is sagittal and osteotomy, the osteotome should not be too deep to avoid damage to the inferior alveolar artery. After the ascending branch is opened by the "cracking" method, the bone piece is opened and the bone piece is opened. Deeply repair the bone under direct vision. When the mandibular ascending longitudinal osteotomy (vertical or oblique osteotomy) is performed, the osteotomy line should remain behind the mandibular hole to prevent damage to the inferior alveolar artery. 3. Nerve damage For example, the mandibular nerve may be accidentally injured in the sagittal split osteotomy of the mandibular ascending branch. Precautions during osteotomy are the same as prevention of damage to the inferior alveolar artery. When the osteotomy and the moving bone segment are completed for fixation, care should be taken to avoid the occurrence of postoperative nerve injury symptoms caused by the compression of the inferior alveolar nerve by the bone segment. 4. Segmental necrosis The reason is mostly caused by excessive peeling of soft tissue or damage to the supply of blood vessels. Therefore, the separation and exposure of the bone surface should not be too large, especially in the distal heart segment (the bone segment near the gingival direction), the surface soft tissue should not be excessively separated, but the soft tissue should be kept as much as possible to maintain blood circulation and ensure bone. Healing. 5. Damaged root tip and pulp necrosis The root is simultaneously cut off because the transverse osteotomy line is too low (too close to the cutting edge or face). Therefore, the possible position of the root tip should be judged. The method includes: preoperative photographing of the X-ray film to detect the position and length of the root, and referring to the data of the normal normal root length, the intraoperative observation shows that the alveolar bone surrounded by the root has a slight elevation. After estimating the root length and the position of the root tip, a transverse osteotomy line is designed in the telecentric direction of the root tip of 4 to 5 mm (the maxilla is above the apex of the maxillary root and the mandible is below the root tip of the mandible). 6. Unconnected bone or poor bone healing Mainly due to poor fixation, insufficient contact of the bone segment, and poor blood supply. Therefore, the bone must be well fixed during and after surgery. Generally, inter-bone fixation (ligation fixation or micro-plate strong internal fixation) is used, supplemented by intermaxillary fixation, suspension fixation, and external stent fixation. In addition, the osteotomy design should consider maximizing the contact wounds when the bone segments (blocks) are connected, and prevent excessive peeling of the soft tissue and the like during the operation.