 Topic for the day is Lefort 1 Osteotomy. The Lefort 1 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 1 Osteotomy? Basically, Lefort 1 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 zygomaticum axillary 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 interorbital 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 infarbited 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 retractor 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 forza, the artery will be encountered posterior to the tuberosity region. Hence, keeping a retractor 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 zygomatico maxilla, zygomatico 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 retractor. Once the section 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 pyreform 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. Hence, complete sectioning of palatine bone should be ensured. No palatine bone should remain 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 doing the procedure. The next step and the final step in the leford osteotomy is the separation of maxilla from the pterigoid plates. Here, this is done with a curved osteotone and it is directed medially and anteriorly at the junction of maxilla with the pterigoid plate. So, at the pterigomaxillary 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 to the tuberosity region at the hammerless and ensuring that the instrument is right at the pterigomaxillary junction. Once pterigomaxillary 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 planted 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 perturbances 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. Once this is rotated in 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 zygomaxillary, zygomaticomaxillary crystal regions. Thus, four 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. Hemorrhage is the most common and significant complication of Lefort 1 osteotomy. The vessel at maximum risk for hemorrhage is a dissenting palatine artery. Usually a bleeding from the source can be visualized and can be controlled with local measures. This is about Lefort 1 osteotomy. Thank you. Hello everyone. Today's topic is anterior maxillary osteotomy. In the previous lecture, we have seen various indications of Lefort 1 osteotomy. And the use of Lefort 1 osteotomy is so wide that it has limited the indications of anterior maxillary osteotomy. Let's see where all is the anterior maxillary osteotomy indicated. Mainly, as its name suggests, this technique is performed in the anterior maxilla or the premaxilla. This technique can be used to resolve any isolated anterior open bite or bimaxillary protrusion in the anterior maxilla. Any excess in the vertical or anterior posterior dimensions can be corrected, provided the posterior occlusion is acceptable. This is a good option to perform to correct any marked protrusion of maxillary teeth. Those patients are not cooperative towards orthodontic treatment. And when orthodontic tooth movement is inadvisable, because of pre-existent pathological resorption or ankylosis, anterior maxillary osteotomy is a good option to consider. Now, similar to the Lefort 1 osteotomy, the segmentalized anterior maxilla will survive opponent's blood supply through a soft tissue pedicle. There are various studies that indicate that any variation in the flat design doesn't affect the postoperative blood supply to the anterior maxillary segment. Therefore, many different surgical incisions have been described for access during anterior maxillary osteotomy. And the blood supply to the maxillary segment can be maintained by a labial buckle or palatal pedicles individually or in a combination. So with this in mind, the three common AMO techniques generally considered are the wound wear technique, vestment technique and trooper techniques. Each of the techniques will be explained in detail. Let's move on to it. Before discussing each technique in detail, let's have a general understanding of how the anterior maxillary osteotomy is performed. Anterior maxilla can be mobilized with two vertical buckle osteotomies, one horizontal osteotomy and a transpiratory osteotomy. One vertical buckle osteotomy is performed on each side of the maxilla through the extraction socket of the first premolar. This is the vertical osteotomy. This is followed by a horizontal osteotomy which is nothing but a medial extension of the vertical osteotomy towards the piriform fossa on either side. The third osteotomy is a transpalatal osteotomy. That means osteotomy across the palate at the first premolar region. These are the three basic osteotomies performed in AMO. Coming to the first technique of AMO which is the viewing door method. In viewing door method, the buckle pedicle is preserved or the maxilla, the segmentalized anterior maxilla is preserved with a buckle pedicle. It is maintained with the buckle pedicle. This is very important to remember. How is this technique performed? This is usually performed under general anesthesia. Once the patient is prepared and positioned, local anesthetic solution is injected into the upper buckle vestibule. Three incisions are used in this particular technique. There are two vertical incisions and one transpiratory incision. The two vertical incisions are carried out just distilled to the first premolar. That is here. This is where the vertical incision is given on either side. So what you have to keep in mind while placing an incision is that the incision should be placed at such a point that it lies on healthy bone once the incision is closed. After the wound is closed, the suture line should be over a healthy bone, not at the osteotomy side. So keep that in mind while placing an incision. Once the incisions are given, extraction of the first premolar is carried out on both the sides. Following this, you give your first vertical osteotomy cut and you remove the desired amount of bone required for the setback of anterior maxillary segment. On either side you remove the desired amount of bone after performing a vertical osteotomy. The vertical osteotomy has a medial extension that forms the horizontal osteotomy towards the piriform region. This is a horizontal osteotomy performed through subperiosteal tunneling. Through both the vertical incisions you perform the horizontal osteotomy beneath the periosteum. If you don't give a separate incision or an opening in the anterior maxilla, you perform a subperiosteal tunneling osteotomy towards the piriform region. This is followed by a transpalatal osteotomy across the palate at the first premolar site. In this diagram, what is marked in white is the palatal osteotomy. So once all the three osteotomies are performed, you need to separate the nasal septum from the maxillary segment. This is performed with a superior fracture of the anterior maxillary segment. You gently out fracture the anterior maxilla and separate it from the nasal septum. So this is the basic procedure carried out for a view under a technique of AMO. Let's see it once again. There are three incisions in total, two vertical and one palatal incision. This is followed by buckled vertical osteotomy through the extraction site of the first premolar. This is extended horizontally towards the piriform aperture followed by a transpalatal osteotomy. Once all the three osteotomies are performed, premaxilla is fractured using finger pressure in a superior direction. After the fracture of premaxilla, the nasal aspect of the palate or the fractured premaxilla can be trimmed using a bone launcher. Remove any bone proportions or irregularities and do a good filing, which will facilitate a very efficient setback. Once this step is over, you perform an intermaxillary fixation and stabilize the anterior segment using bone plates at the piriform region. This is how a view under a AMO is performed and the most important thing to be remembered is that the anterior maxillary segment is preserved with a buckled pedicle. So this is about view under a method. The second anterior maxillary osteotomy technique is the Wassman, which preserves both the buckle and palatal soft tissue pedicles. Unlike the view under a method where only the buckled pedicle is preserved. It is however more difficult to gain access to the palatal aspect of the anterior maxilla with this kind of incision. There are three incisions. All the three are vertical incisions placed on the buckle aspect. Two vertical incisions are made at the extraction site of the first premolar or at the intended osteotomy sites. The third midline incision is given to gain access towards the anterior nasal spine. Through this anterior incision, it is possible to elevate and protect the nasal flow and to separate the nasal septum from the maxillary crest. So there are three vertical incisions placed. After the incisions are given, the buckle vertical osteotomy is performed at the extraction site of first premolars on either side similar to that of view under a technique. Vertical osteotomies are performed and the buckle horizontal osteotomy is created by tunneling through the anterior and posterior buckle incisions. As already explained in the view under a technique, there is a horizontal osteotomy which is nothing but a medial extension of the vertical osteotomy. This is performed subperiostally between the anterior and posterior incisions. Following horizontal osteotomy, the transpalytal osteotomy is created. You know there is no transpalytal incision. So how is the transpalytal osteotomy performed? It is performed through the buckle vertical osteotomy on either side. It is created through the buckle vertical osteotomy on either side by maintaining a digital palpation of the palatal mucosa. While performing the palatal osteotomy, place your index finger at the palatal mucosa just to ensure that the palatal tissues are not traumatized during the procedure. There is no direct access to the palatal bone, hence keep a palpating finger at the palatal mucosa just to ensure its safety. Now the transpalytal osteotomy may be also facilitated by use of a mid-palatal sagittal incision. As seen in this diagram, if you facilitate the procedure, you may place a vertical incision. Just to gain direct access to the thick bone of the mid-palate. These are the three osteotomies performed. Two vertical osteotomies, one buckle horizontal osteotomy through subperiostal tunneling a palatal osteotomy as an extension of the buckle vertical osteotomy. Taking care not to damage the palatal tissues. Once the osteotomies are performed, the anterior maxillary dentosary segment can be repositioned. Similar to the Jungler technique explained, once the osteotomies are completed, the pre-maxilla is fractured, placed in inter-maxillary fixation and then stabilized using bone plates. So this is regarding Wassmann method of anterior maxillary osteotomy. Moving on, the third anterior maxillary osteotomy technique is the Kuiper technique which is a minor version of total maxillary osteotomy down fracture. In this technique, the palatal pedicle is kept intact which ensures re-vascularization of the segmentalized anterior maxilla. A buckle vertical incision is created 4 to 5 mm above the muco-gingival junction extending from the zygomatico-maxillary butt-wiss on one side to the other. A full-thickness muco-periostal flap is raised exposing the anterior lateral maxillary walls, the piriform aperture, the nasal floor and the nasal septum. In this technique, the sequence of osteotomies is operated dependent but the general procedure involves completion of the vertical, buckle and horizontal osteotomies under direct visualization. Prior to performing an osteotomy, the nasal mucosa is elevated from the superior surface of maxilla. It is easier to complete the osteotomies if the nasal septum is first released from the maxillary crest. The horizontal osteotomy is then completed. It extends from first premolar on one side to the other. The buckle horizontal osteotomy extends from one premolar to the other and this is followed by down fracture of the anterior maxilla using digital pressure inferiorly. This is similar to the Lefort 1 osteotomy technique. Once the down fracture is performed, you carry out the vertical osteotomy bilaterally. This is done through the extraction socket of first premolar on both sides. Next, you perform the transpalatal osteotomy. So, before placing an osteotomy cut on the palate, similar to the Wassman technique, a finger is placed on the palatal mucosa to palpate the osteotom to prevent any tissue damage as the osteotom is advanced. The transpalatal osteotomy is then completed under direct visualization from above. That is, from here you have a direct access to the palate and under direct visualization, the transpalatal osteotomy is carried out. This also allows good access to the nasal crest of maxilla and the mid-palatal bone for OSHA's reconquering. As it was done in Lefort osteotomy for superior repositioning of maxilla, OSHA's reconquering in this area is required. Once OSHA's reconquering is done, the maxilla is repositioned and placed in IMF. Following IMF, stabilization of the repositioned maxilla may be completed with bone plates or wires. This is the technique of antihill maxillary osteotomy cupor method. What is the advantage of cupor method over the other two techniques? There is direct access to nasal structures. Because we are performing a down fracture here, you have direct access to the nasal structures as well as direct visualization of the palate to carry out the transpalatal osteotomy. Also the predicle we preserve is the palatal one which supplies vasculature to the segmentalized maxilla. The fixation also is easier in this technique. So this is regarding anterior maxillary osteotomy. Thank you. Hello everyone. Today let's discuss about bilateral sagittal split osteotomy or BSSO. Also known as bilateral split ramus osteotomy or simply sagittal split osteotomy. Sagittal split is a versatile technique which enables movement of mandible in the anterior posterior direction. Let's see how this highly flexible technique has evolved over time. Though the technique was first described by Schuchat in 1942, it was popularized by Obvigizer in the year 1955. Dalpone has given a major modification to the procedure by extending the oblique cut to the second molar region. Hansen modified the medial cut by extending it just behind the mandibular flamin. Epker later extended the vertical cut up till the inferior border of mandible. So this is how the technique of sagittal split has evolved over time. What are the indications of sagittal split? This technique can be used to treat both the retrognathism and prognathism of mandible. Horizontal mandibular axis, horizontal mandibular deficiency and mandibular asymmetry are few indications of sagittal split. If the mandibular advancement is to exceed 10 to 12 mm, then an extraoral approach has to be considered. Whereas if the mandibular setback exceeds 7 to 8 mm, then intraoral vertical ramus osteotomy or an inverted L osteotomy is considered, not a sagittal split. Before moving on to the technique, let's have a quick look at the anatomy relevant to sagittal split osteotomy. This is a medial view of mandible where you can see the mandibular flamin. It is through this mandibular flamin that the inferior alveolar nerve enters into the inferior alveolar nerve canal. At the opening of the flamin, there is a tongue-like bony projection known as lingula. The first medial osteotomy cut is performed just superior to the lingula extending just behind the flamin. In this lateral view of mandible, you can see the ascending ramus and the external oblique ridge. The second osteotomy cut of sagittal split is performed through this external oblique ridge extending up to the second molar or the first molar. The third vertical osteotomy cut connects the oblique cut to the inferior border of mandible. So for a better understanding of the procedure, keep this picture in your mind. Let's now move on to the technique of sagittal split. The procedure is usually done under general anesthesia with a patient in supine position. Local anesthetic solution is infiltrated into the buccal vestibule along the ramus on both the sides. The landmarks those need to be kept in mind are the anterior border of ramus, the external oblique ridge, lingula and mandibular flamin. Coming to the incision. The incision begins at the middle of anterior ramus. This is the ascending ramus and this is approximately the mid ramus. From the middle of the ramus, the incision is extended inferiorly along the external oblique ridge towards the first molar and it then curves down to the buccal vestibule. So this is the path followed by incision. Initially, only the mucosa is incised. You need to retract the tissues buckly before deepening the incision to prevent any infiltration of the buccal pad of fat into the surgical site. So this is to be remembered that the tissues on the buccal side has to be retracted before deepening the incision. The incision is then cut through the submucosa, muscle and periosteum. So once the incision is completed, periosteum is elevated using a periosteum elevator. The tissues on all the three sides has to be retracted. Superiorly, the tissues are retracted to expose till the tip of the coronoid. The tip has to be visible after retraction. Then retract laterally till the inferior border of the mandible. On the lateral side, you reflect the tissues till you see the inferior border of mandible. And on the medial side, expose the internal oblique ridge and up till the superior and posterior portion of the lingula. On the medial side, you need to expose the internal oblique ridge and the superior portion as well as posterior region of lingula. Also, you need to relieve the temporalis fibres from the medial side of coronoid. As you know, the fibres of temporalis muscle gets attached to the tip of the coronoid. Therefore, it is necessary to relieve the fibres from here. So, once the soft tissue dissection is over, you proceed with the bone osteotomies. Before we describe each osteotomy in detail, let's have a look at what are the different osteotomies used in sagittal split. There are three osteotomy cuts used in a sagittal split. The first one is a medial horizontal cut. The medial horizontal osteotomy is performed on the medial aspect of the mandible. Then, the second cut is a oblique one. It is an oblique one and it is an intermediate one. So, it extends from the medial cut down towards the external oblique ridge towards the molar region. This is the intermediate oblique osteotomy. The third osteotomy is a vertical buckle cortical osteotomy which is performed from the lower border of the mandible and it connects to the oblique cut. So, there are three osteotomies basically. A medial horizontal osteotomy, an intermediate oblique osteotomy and a vertical buckle cortical osteotomy. Now, let's see each of these osteotomies in detail. Medial horizontal osteotomy is performed first using a reciprocating saw or a burr which is inclined at an angle of 45 degrees to the bone surface. The bone cut should extend superior to and posterior to the lingula. That is about two-third the anterior posterior dimension of the ramus. It should be kept in mind that the bone cut should extend into the medullary bone and not just remain within the cortical bone. Also, the cut should be made in such a way that it is parallel to the occlusion plane. The intermediate oblique osteotomy is an extension of the medial horizontal cut. This osteotomy is taken downward through the external oblique ridge towards the second molar region. This intermediate oblique osteotomy should be parallel to the lateral contour of the mandible. Remember that this bone cut should be parallel to the lateral surface of the mandible. The oblique osteotomy can also be extended towards first molar region just for better accessibility. Prior to performing the vertical buccal cortical osteotomy, protect the soft tissues at the lateral and inferior border of the mandible using a channel reactor. The vertical osteotomy should involve the lower border of the mandible. The vertical cut starts from the inferior border of the mandible. It goes up straight perpendicular to the occlusion plane. It goes for about two centimeters before joining the oblique cut. Hence, all the three osteotomies are completed. The first osteotomy cut is the medial horizontal osteotomy. The second one is the intermediate oblique. And the third one is the vertical buccal cortical osteotomy. Once you have performed all the three osteotomies, it is now time to complete the societal split. A small spatula osteotome is used to mallet from the medial to the vertical cut. That means the osteotome is used beginning from the medial horizontal cut along the oblique intermediate osteotomy and then finally to the vertical cut. Make sure that the osteotome is directed towards the lateral side of the mandible and not towards the medial side. Also be careful not to damage the neurovascular bundle. Once the osteotome is used to mallet from the medial cut to the vertical, then use a smith spreader to complete the societal split in a prying motion. The smith spreader is used in a prying motion to complete the societal split. Any incomplete prying or any incomplete split can lead to adverse fracture. So keep in mind that the prying should be complete and the split also should be complete. It is important to visualize the neurovascular bundle throughout the procedure while performing a societal split. Visualize the neurovascular bundle and always maintain it in the medial or the proximal segment. What is the medial segment? The segment that contains the condylar head is known as the medial segment and the segment that bears the teeth is the distal segment. So keep in mind the one that bears the condyle is the proximal segment and the one bearing the teeth are the distal segment. In case the nerve bundle is embedded within the bone, in the proximal segment if it is embedded within the bone it is important to relieve it from between the bone irregularities. Otherwise this can lead to a nerve injury or temporary nerve damage later on. In case of advancement, in case you are advancing the mandible, separate the medial teregoid muscle from the inferior border of the distal segment. As you know the medial teregoid gets attached to the middle aspect of the mandible. So if you are advancing the mandible, make sure that the medial teregoid attachment is relieved from the distal segment because we don't want any stretching of the muscle as you advance the mandible forward. In case you are doing a mandibular setback, again you need to strip off a certain amount of the terego masatric sling. So here make sure the stripping is minimal. If the stripping is excessive, there are chances that the segment will not survive and there will be necromancy. After the split is complete and the neurovascular bundle is preserved, the mandible is then advanced or setback as required. It is a distal segment that is advanced forward or which is setback. In a setback, the desired amount of cortical bone is removed from the distal segment. That means the desired amount of cortical bone is removed from here, this aspect of the distal segment. Why is it done? So that it doesn't override with the proximal segment. When you take the distal segment behind, it should not override with the proximal segment. For that reason, a small amount or the desired amount of cortical bone is removed. And it is also done so that both the segments, both the proximal and the distal segments, maintain a cancerous bone contact. When a small portion of cortical bone is removed, then it is the cancerous bone which comes in contact and this will enhance healing. So this is how the mandible is brought forward or behind, following a sagittal split. Once the mandible is repositioned, occlusion needs to be checked and confirmed. Then the maxilla mandibular complex is placed in an IMF. And like in any other osteotomy in sagittal split also, the bony segments are fixed using either a rigid internal fixation, bone plates, a large bone plate in case of advancements or lag screws or wiring. If bone wiring is used, then IMF needs to be maintained for another 5 to 6 weeks. This is how the distal and the proximal segments are stabilized and fixed. Postoperative complications like edema, diminished sensation of lips and limited jaw movements are often experienced by the patients. Few other complications include a wrong split. When a third molar is removed during the time of surgery, there are chances that the sagittal split can turn into an unfavorable fracture. So it is advised to have the third molar removed at least 6 months prior to the surgery. Also, neurosensory deficit has been observed among patients who have undergone a bisagittal split. So if a nerve is cut or transplanted during the surgery, it is advised to perform a microanastomosis. Also, care has to be taken while plating both the distal and proximal segments because an improper plating can either push or pull the condyle into an untoward position and this can lead to TMG problems and relapse later on. Another complication is excessive bleeding. It can be from inferior alveolar neurovascular bundle or medullary bed or even from facial vessels. So if the bleeding is from an inferior alveolar neurovascular bundle or if it is a bone bleed, it can be controlled using local hemostatic measures. If the bleed is from facial vessels, then the vessels have to be clamped and tied, and it can be done only through an incision performed extra overly. So these are the complications with sagittal split osteotomy and this is all about bilateral sagittal split osteotomy. Thank you. Hello everyone. Today, let's discuss about geneoplasty on how it's done and what are its various types. This is one of a prominent facial features and the society tends to describe one's personality characteristics based on the chin features. Geneoplasty is a surgical procedure which is used to re-contour or reposition the chin. Like any other ortho-natic or osteotomy procedures, geneoplasty has also undergone evolution in its technique over the time. In 1942, who introduced horizontal osteotomy in the same crisis region through an extraoral incision. Later in 1957, Prawner and Obfegacer performed horizontal osteotomy following de-gloving of the anterior mandible using an intraoral incision. As you can see in this figure, the osteotomized segment of the chin of the anterior mandible can be repositioned in all three planes of space, that is the vertical, anterior posterior and transverse planes. Let's now move on to the surgical procedure. Geneoplasty is usually performed under general anesthesia. Once the patient is positioned, local anesthetic solution is infiltrated into the lower labial vestibule. Incision is then placed on the lower labial mucosa approximately halfway between the depth of the vestibule and the wet dry line of the lip. The incision extends to premolar region on both the sides. Once the mucosa incision is completed, the mentalist muscle is then divided and the incision is deepened till the periosteum. Periosteum is incised and a full thickness flap is raised to expose the inferior border of the mandible. So first you perform an incision on the labial mucosa, then the mentalist muscle is divided and the incision deepened to cut the periosteum. After periosteum is incised, a subperiosteum dissection is carried out to expose the inferior border of the mandible. After you have raised the flap, mental nerve is visualised on both the sides and is preserved throughout the procedure. Therefore from the anterior mandible you strip off all the soft tissues, that is the mucosa, the submucosal layer, the muscles and the periosteum. So this is like removing gloves from your hands and hence this is called de-loving of the anterior mandible. The next step is the osteotomy which is performed using a reciprocating saw or an oscillating saw. Prior to performing the osteotomy, it is always preferable to inscribe the proposed line of osteotomy using a thin burr. This is the proposed line of osteotomy. The osteotomy cut is made at least 4.5 mm below the apices of the anterior teeth. Approximately here you have the anterior teeth roots. At least 4.5 mm below the apices you make the osteotomy cut. And this osteotomy is at least 10 to 15 mm above the inferior border. The distance from the osteotomy cut to the inferior border should at least be 10 to 15 mm. Also the posterior ends of the osteotomy. The posterior ends means these two ends. Should be positioned below and behind the mental phramon on both the sides. On either side the posterior end of the osteotomy should be below and behind the mental phramon. And make sure the cut is symmetric through the buckle and lingual cortices throughout. There shouldn't be any incomplete osteotomy. The cut should be symmetric and complete through both the cortices. Now the osteotomy is complete and next the segmented portion needs to be freed from the rest of the mandible. This is the segmented inferior portion which needs to be freed from the rest of the mandible. But here remember to keep the segment particular to the digastric and genome hyoid muscles. How are the digastric and genome hyoid muscles related to anterior mandible? The anterior belly of the digastric muscle originates from the digastric forza at the inferior border of anterior mandible. And genome hyoid muscle originates from the inferior geniotubical which is present on the medial aspect of the anterior mandible. Why should you keep the segment predical? If you make the segment a free graft that means if this segment doesn't have any muscle predical attachment or a periosteal attachment it becomes a free graft and there will be intense inflammatory reaction and avascular necrosis. So for this reason make sure the inferior segment is predical. Now that the osteotomy is complete let's see how all can the osteotomized segment be repositioned. This is an example of augmentation geneoplasty wherein the cut segment the cut inferior segment is moved anteriorly and fixed using wires or semi-reject plates. So in this case the chin is advanced. You may also perform a retro positioning of the chin. You can push the chin behind. An important factor to consider here is the good adaptation of the soft tissue following chin repositioning. But in the reduction of chin the soft tissue adaptation following the posterior repositioning is not 100% age. For this reason a concavity may be carved into the anterior mandible. That is you contour the anterior portion of the mandible so that the soft tissue of the chin can maintain their natural contour. Moving on for major advancement of the chin you can perform a stepwise augmentation. That is the osteotomized inferior segment is again cut and sliced more than once. So there are more than one horizontal segment and both the segments can be moved forward. But this is now a less commonly used technique due to the advent of rigid internal fixation. However far the inferior segment is moved it can now be fixed. Therefore this augmentation is not commonly used these days. Genioplasty can also be performed to correct facial asymmetry. For example if the chin midline doesn't coincide with the facial midline you perform a modified osteotomy and a bone graft is removed for example from the left side. You then move the osteotomized segment towards the left and fit this bone graft back into the right side. This is an osteotomy plan for mild facial asymmetry pertaining to the chin. This is an example of an extended genioplasty which is used in case of major facial asymmetries. Here again you follow a degloving incision to expose the mental nerve and the body of the mandible. Osteotomy is extended to the antagonial angle that is anterior to the mandibular angle. You extend the osteotomy. This is followed by laterally sliding the lower border of mandible thus correcting the facial asymmetry. You move the segmentalized inferior border towards the side of deficiency thus correcting the asymmetry. This procedure is advocated in patients undergoing correction of facial asymmetry due to hemifacial microsomia or unilateral ankylosis of temporal mandibular joint. We have now had a look at the various applications and techniques of genioplasty. Following osteotomy the occlusion is checked and confirmed using occlusion splint. The segmentalized inferior border may be stabilized and fixed using figure of 8 wiring or bone plate. Few of the complications associated with genioplasty are edema, sensory loss due to damage to mental nerve, wound essence, avascular necrosis of segments and chintosis due to mishandling of mentalis muscle. That's all about genioplasty. Thank you. Hello and welcome back to OMFS lecture series. The topic for today's lecture is mandibular sub-apical osteotomy. Mandibular sub-apical osteotomy is performed to reposition the dental alveolar segment and is done in the anterior posterior of the entire dental alveolar segment of the mandible. Coming to anterior sub-apical osteotomy. First described in 1849, anterior sub-apical osteotomy was mainly indicated to correct the proclined lower anterior dental alveolar segment. Other indications include closure of minimal anterior open bite and advancement of anterior teeth. It is also indicated in bimaxillary protrusion in combination with anterior maxillary osteotomy. Let's now see how the surgery is performed. Local anesthetic solution is infiltrated into lower labial vestibule. A sulcus incision is placed and a full thickness mucoperiostial flap is raised to expose the inferior border of anterior mandible and mental ferraments on either sides. As being already explained in the lecture on genioplasty it is important to preserve the muscle attachment at the inferior border of anterior mandible. Next, a subperiostial tunneling is done on the lingual side. This is in order to facilitate the dental alveolar segment. Once it is sectioned in case of dental alveolar segment set back extraction of first premolar is done on either sides. If the intended plan is to reposition the dental alveolar segments superiorly. If this segment is to go up then there is a gap that is left at the osteotomy side. This gap is later filled using bone grafts. As you can see in these photographs this is the osteotomy performed following which the dental alveolar segment can be repositioned as required. Once the osteotomy is complete and the segment repositioned it is then stabilized and fixed using bone plates or lag screws or even wires. This is a photograph showing the sub-opical osteotomy being performed along with genioplasty. Here, sub-opical osteotomy is performed in combination with genioplasty. Let's now move on to sub-opical osteotomy of mandible. It was first described by McIntosh in the year 1942 and used to reposition the entire dental alveolar segment. Make sure at least 10 mm of bone to be present below the epizes of teeth before performing the osteotomy cut. Like in any other mandibular ortho-netic surgical procedures here also the basic principle is to reflect the buccal mucoperiosteum down to the inferior border and taking care not to injure the mental nerve. Later, the lingual periosteum is also elevated without any damage. The first step here is to remove the buccal cortical plate just behind the mental ferramen. That means if the mental failure you remove a certain amount of buccal cortical plate. Why is it done? This procedure is done to release the neurovascular bundle from within the bony enclosure. You have the inferior alveolar nerve bundle passing through the canal within the body of mandible. So in order to release the nerve bundle from within the bony enclosure using a fissure bur a window is created on the outer cortical plate. And then the cancerous bone around the nerve bundle is removed and the nerve is released using a nerve hook. So in this way you expose and preserve the inferior alveolar nerve bundle. What is the next step? Osteotomy is started here. That is just behind the most posterior tooth present. If it's the second molar you create a osteotomy cut just posterior to it using a reciprocating saw or an oscillating saw. The osteotomy cut is continued through the window towards the midline. From here the cut follows through the window towards the midline. All this while the nerve is still preserved. As you can see in this diagram this is the osteotomy cut and you have kept the nerve at a safe position using a nerve hook. The same procedure is repeated on the other side as well. So a 4 mm of bone should be still left below the teeth apises. That means this distance from the teeth apises till the osteotomy the distance should be at least 4 to 5 mm. And the distance from the osteotomy cut till the inferior border should be at least 10 mm. Once the osteotomy is completed the dental alveolar segment is then mobilized and repositioned. Like you can see in this diagram. The neurovascular bundle is also repositioned and secured using pieces of bones. So this is how a total sub-apical osteotomy of mandible is performed. Repositioned dental alveolar segment is then stabilized and rigid internal fixation is performed. Postoperative sequelae includes edema and sensory disturbances which will subside in about 2 weeks time. The importance of good blood supply through the lingual pedicle is of at most important for the segment to survive. So this is regarding total sub-apical osteotomy of mandible. Thank you.