 The topic for the day is Lefort one osteotomy. The Lefort one osteotomy has become the workhorse of orthodontic surgical procedures. It is a technically easy procedure with broad applications to resolve many functional and aesthetic problems. It is important to understand the biologic basis of any facial bone osteotomy. The revascularization studies of Bell and Fonseca indicate that the maxilla may be mobilized and repositioned and the survival continues as long as the mobilized maxilla remains attached to a broad soft tissue pedicle. It means that maxilla can survive as long as the blood supply to it is intact and unhampered. What are the indications of Lefort one osteotomy? The Lefort one osteotomy can be performed to mobilize and reposition maxilla in all three planes namely the vertical, anterior, posterior and transverse planes. Coming to the surgical technique. With all facial bone procedures positioning of the patient at the time of maxillary osteotomy is very important. The patient's head should be elevated approximately 10 degrees and a diluted solution of local anesthesia with epinephrine is injected into the mucosal tissues of the upper lip. Coming to the incision. The oral incision is placed high in the mucobuccal fold of the upper lip. It extends from the zygomatico maxillary butt waste region on one side to that of the opposite side crossing the midline. Incision may be placed using either a scalpel blade or a thermal knife. It is placed in such a way that it facilitates subperiostal dissection to the orbital rim thus exposing the infrarbital now. After this the dissection of the posterior maxilla is performed. A tunneling is performed in order to preserve a broad base intact mucosal pedicle to ensure an intact blood supply to the sectioned maxilla. Design of the lateral wall, lateral maxillary osteotomy is tailored to the patient's aesthetic needs. Not on every patient same sort of osteotomy design is performed. For example the first diagram shows a low level osteotomy. The second and third diagram shows an osteotomy with modification in the infrarbital region. And the fourth diagram depicts a low level horizontal osteotomy with no vertical sections. The first osteotomy that we perform is that of the lateral wall of maxilla. This initiates at the zygomatic or maxillary buttress region on one side. This is performed using a reciprocating saw and proceeds towards the anterior region towards the nose. So normally here a reactor is placed that is at the junction of the maxilla with the pterigot plate. This is to provide adequate exposure and ensure safety of maxillary artery and its branches. So how does maxillary artery appear here? As they descend the pterigopalatine fossa, the artery will be encountered posterior to the tuberosity region. Hence keeping a reactor posterior to the tuberosity minimizes the risk of damaging the artery and its vessels. Following osteotomy of lateral wall of maxilla, osteotomy of posterior wall is performed by moving the reciprocating saw in an inferior direction from the zygomatic or maxillary buttress region. So from the buttress, the saw is directed inferiorly towards the pterigot plate. You continue to protect the vessels behind the tuberosity using a reactor. Once the sectioning of posterior wall is completed, the next step is to section the lateral nasal wall. During this procedure you need to free the cartilage and the bone of nasal septum and warmer from maxilla. How is it performed? An osteotome is placed at the pyrefoam rim and directed posteriorly and inferiorly. It is directed posteriorly and downward inferiorly along the lateral nasal wall towards the perpendicular plate of palatine bone. So basically you are separating the nasal septum from maxilla, okay? Hence complete sectioning of palatine bone should be ensured. No palatine bone should be remained attached to the maxilla. This can lead to fracture that extends up till the orbit. Hence ensure a complete sectioning of the palatine bone. This is performed using nasal septum osteotome. This is a nasal septum osteotome and special care should be taken to preserve the nasal mucosa as well. The mucosa should not be damaged while during the procedure. The next step and the final step in the leford osteotomy is the separation of maxilla from the terrigoid plates here. This is done with a curved osteotome and it is directed medially and anteriorly at the junction of maxilla with the terrigoid plate. So at the terrigomaxillary junction, you place a curved osteotome in a medial and anterior direction. Hence this junction is performed. Again you should take care that the palatal mucosa is not torn or damaged during the procedure. So for this you can keep a finger posted at the tuberosity region at the hamilis and making and ensuring that the instrument is right at the terrigomaxillary junction. Once terrigomaxillary disjunction is performed, the next step is to down fracture the maxilla with hand pressure. You hold maxilla in the anterior region and perform a down fracture. Following this a bone raunger is used to remove any remaining warmer or nasal crest of maxilla. This is done in particular if repositioning of maxilla is planned in superior direction. In superior repositioning there are chances that any bony hindrances or bony irregularities will affect the repositioning. Hence use a raunger to remove any bony protrobrances or irregularities. Next after down fracturing is complete maxilla is placed in intermaxillary fixation. This is intermaxillary fixation where maxilla and mandible is fixed together. This is performed after rotating the maxillomandibular complex into the desired position. Since this is rotated into the desired position and the contiles are placed properly, you perform a maxillomandibular fixation. This is followed by stabilization of the repositioned maxilla using bone plates. Usually 1.5 mm bone plates are used to stabilize the maxilla. These are placed mainly at the pyriform rim and zygomaticomaxillary crystal regions. Thus 4 plates are used to stabilize maxilla. Following this the incision is closed in layers. Now what are the complications of Lefort 1 osteotomy? There might be wound infection, bone sequestrum formation, any sort of neurologic deficit. There could be widening of allerbis and emphysema. These are very rare complications that happen. But the most common and significant complication related to Lefort 1 osteotomy is hemorrhage. The vessel at maximum risk for hemorrhage is a dissenting palatine artery. Usually bleeding from the source can be visualized and can be controlled with local measures. This is about Lefort 1 osteotomy. Thank you.