 Let's begin a new topic with this lecture, surgical management of jaw tumors. As you know, neoplasm of oral cavity can arise from a variety of different tissues. For example, salivary glands, muscles, blood vessels or remnants of dental follicles. Treatment of tumor is planned after its staging. When malignancies of oral cavity are created with surgery, radiation, chemotherapy or a combination of these modalities, for benign or non-metastatic tumors, surgery alone is sufficient. This is one of the classifications of odentogenic tumors and there are still many more. Detailed lecture on each of these lesions has already been discussed, the links of which is given in the description box. In this lecture, we shall be discussing the various surgical management techniques of benign odentogenic tumors associated with mandible. Let's now understand what are the principles of surgical management of jaw tumors. The first and foremost principle is complete eradication of the lesion without leaving behind any remnant pathology. Try to preserve the normal tissues and vital structures to the extent permitted by the disease and the surgical technique. Minimize the morbidity by avoiding unnecessary excision. So, keep in mind the patient's quality of life post surgery. Only the excision of the lesion will not suffice. Restoring the lost tissues, the form and function is also of equal importance. And a long-term follow-up with clinical and radiographic evaluation is mandatory to check for any recurrence. So, these are the basic principles while planning any surgery for tumor management. Before planning the surgical procedure, the Orlean maxillofacial surgeon should discuss the biological behavior, the histology tissue pattern and recurrence rate with the pathologist and should correlate the clinical, radiological and histopathological findings. In 1991, Gold, Upton and Marx have presented a standardized surgical terminology for the excision of lesions in the bone. All the excisions of the lesions involving the jaw bone is described by the following terminologies. Those are inoculation, cutotach, marsupilization, recontoring, resection without continuity defect, resection with continuity defect and disarticulation. In order to choose the most appropriate surgical method, the following factors are to be considered. The first factor is the anatomical location of the lesion. The surgical access to the lesion is an important factor for prognosis. A small benign lesion in an inaccessible area is more difficult than an aggressive lesion in an accessible area. For example, a small tumor at the tergomaxillary fissure, where it is comparatively difficult to access, is more difficult to treat when compared to an aggressive tumor or a malignancy in the anterior mandible, which is more accessible and have better prognosis. The second factor is the aggressiveness of the tumor. Locally invasive tumors are treated with wider resection or a more radical treatment is given in order to prevent recurrence. Size of the tumor and confinement to the bone. The size of the tumor is important, especially in the mandible. If the inferior border of the mandible is not involved in the lesion, then a marginal resection can be carried out without any continuity defect. But if the tumor is not confined to the bone, that means if it has perforated the cortices and extended into the soft tissues, then one has to carry out wider resection, the sacrificing more amount of normal tissues along with certain vital structures. Next factor to consider is the proximity to adjacent vital structures. Preservation of the neurovascular structures and dentition is of importance to reduce immobility and to restore the function. But if the tumor is aggressive, then both these important structures have to be sacrificed. Involvement of maxilla or mandible. The maxillary tumors have poorer prognosis when compared to those involving the mandible. It is because of the cancellous nature of the maxilla. Because the bone is more cancellous or more porous, there are chances that the tumors grow asymptomatically and extensively to attain a large size with late symptoms. Also proximity to certain structures like maxillary sinus, nasal cavity, orbital cavity, all these will contribute to the extensive nature of the tumor. The last factor is the rehabilitation or reconstruction. The rehabilitation is much easier in the mandible than in the maxilla. The continuity of the resected mandible can be maintained by using reconstruction plates. Bone grafting can also be done as a primary reconstruction method or a secondary method. The first among the surgical treatment modalities of jaw tumors is enucleation with or without cutotage. Cutotage is the removal of pathological tissues by means of vigorous scraping along the cavity walls or along the bone margins of the lesion. This procedure is indicated in surgical excision of the tumors which tend to grow by expansion rather by infiltration of the surrounding tissues. Lesions occurring in the bone with a distinct separation between the lesion and the surrounding bone is excised by this procedure. And often in such lesions there is a cortical margin of bone that differentiates the tumor or cyst from the bone. Enucleation is mainly used for excision of a well-encapsulated cystic lesion because it is not a definite procedure and has high recurrence rate. A widely used surgical procedure is the marginal resection or resection without continuity defect. What does it mean by without continuity defect? It means that the inferior border of the mandible maintains its continuity. There is no breach or break in the lower border of mandible at any point. So it is also termed peripheral osteotomy or end block resection. In this procedure the tumor is removed along with the rim of uninvolved bone while maintaining the continuity of the jaw. End block resection is indicated in the benign lesions which are known for its recurrence or in those lesions that are incompletely encapsulated or tend to grow beyond their surgically apparent capsule. It is also indicated for recurrent lesions previously treated by enucleation alone. So this procedure allows complete excision of the tumor but at the same time a continuity of the jaw bone is retained and thus deformity, disfigurement and the need for a secondary cosmetic surgery or throstatic rehabilitation are avoided. Now let's see how the surgical procedure is carried out. There are two approaches followed, intraoral and extraoral. In intraoral approach, circumgingival incision is taken along the necks of the teeth including one or two teeth on either side of the involved teeth. That means if this is the tumor involving the central incisors and lateral incisors in the anterior mandible, your resection will include canine and the first premolar on either side. So in total eight teeth are involved in the resection. So after the incision is made, a full thickness mucoperiostal flap is reflected using a periostal elevator. Take care not to perforate the lesion. If the lesion is perforated then the overlying mucosa should also be sacrificed along with the tumor excision. So the teeth next to the tumor, that is the teeth just adjacent to the tumor mass is extracted on either side. The vertical osteotomies are performed through the sockets of these extracted teeth. As you can see in the diagram, if here was the extracted teeth on either side, vertical osteotomies are performed through their extraction sites using a burr or saw blade. Both the vertical osteotomy cuts are extended from buccal to lingual cortices. You know that the mandible has two cortices, buccal and lingual. So the osteotomy cuts should extend from buccal to lingual by cortical cut. The cuts are then joined with a horizontal osteotomy which is placed well beyond the tumor mass. And this includes a margin of normal bone which measures approximately 0.5 to 1 centimeter depending upon the histopathological nature of the lesion. Make sure that the horizontal cut is also completed through and through the buccal and lingual cortices. The complete excision of the tumor along with some amount of normal bone is carried out by using osteotomy. The teeth involved in the tumor mass is also removed. The remaining bony margins should be then checked for sharp perias and contoured by using round burrs or bone file. Whatever excess of mucoperiostal flap is present, it is trimmed off and approximated to suture the wound. This type of excision that is marginal resection can be performed under local anesthesia with sedation. For smaller lesions, in case of larger lesions, it can be planned under general anesthesia. This diagram shows the intraoral approach for a lesion for marginal resection in the posterior mandible. This is a clinical photograph showing marginal resection performed in the canine tremolar region. You can appreciate the two vertical cuts and the horizontal cut involving both the buccal and lingual cortices. Here the disease had involved the mucosa also. Therefore, mucosa is excised along with the tumor. This is the resected specimen. For large lesions in the posterior mandible, extra aural approach is followed. Submandibular incision is taken and the inferior border of mandible is exposed. If required, the posterior border of ramus is also exposed. The site of osteotomy is decided by studying CT scans of radiographs. Drill holes are made in the healthy bone around the periphery of the lesion. If this is the tumor, you need to include some amount of normal surrounding bone also in the specimen. These holes are then connected and the lesion or the specimen to be excised is separated from the intact inferior border of mandible. You are preserving this part of the mandible in marginal resection. Now, the part has to be excised. This is the part that has to be excised. This needs to be detached from its soft tissue attachments. What are the soft tissue attachments? On the external surface of mandible, the specimen is attached to mesater and buccanator. On the medial aspect, it is attached to medial tergoid and mylohyoid muscle. First, the mesater and buccanator muscles are detached with care so that the branches of facial nerve are not injured. Then, an intraoral incision is given and the mucoperiosteum of the alveolar process is elevated. Now, the specimen can be turned outwards. That means you can swing this after the osteotomies are performed. You are free to swing the specimen laterally or towards outside. At this time, you can detach the mylohyoid and the medial tergoid muscles from the medial aspect of the specimen. Coronoid has attachment of temporalis muscle. So, after the medial soft tissues have been detached, you then detach the temporalis attachment from the coronoid process. The next step is to identify the inferior alveolar nerve. Here is the inferior alveolar nerve and the vascular bundle associated with it. So, after all the major muscular attachments have been detached, the inferior alveolar neurovascular bundle is identified. It is grasped with a hemostat, ligated and cut off. This is done to prevent any major hemorrhage. So, once this procedure has been performed, hemostasis is achieved and the remaining bone, the remaining surrounding bone is carefully inspected. Any sharp margins are filed off and intraoral wound closure is performed. It should be a watertight suturing. Watertight suturing has to be performed for the intraoral incision. Following this, an immediate bone graft is inserted through the extraoral wound and fixed with intraoscious wires or bone plates. You know that reconstruction is an important aspect of marginal resection, especially in the posterior mandible. Therefore, you place a bone graft and then fix it with bone plates. The wound is then closed in layers with a small rubber drain inserted. Rubber drain is inserted to prevent formation of hematoma. After wound closure, an external pressure bandage is applied and careful long-term follow-up is mandated. The next surgical procedure is segmental resection. In this technique, continuity of the inferior border is not maintained. Depending on the extent of involvement, a partial or hemimandublectomy is performed. Hemimandublectomy means one entire half of the mandible is removed or resected. That is hemimandublectomy. What are the indications of segmental resection? It is indicated for treatment of lesions that are infiltrative or have a tendency to recur. Those lesions which extend close to the inferior or posterior border of the mandible, the maxillary sinus or nasal cavity. It is also used for malignant lesions with high recurrence potential. In maxillary amyloblastomas with high recurrence rate. And also in lesions close to the borders of the jaw with the possibility of postoperative pathologic fracture. These are the indications of segmental resection or partial mandublectomy or hemimandublectomy. Moving on to the procedure of segmental resection. It has two approaches, intraoral and extraoral. In intraoral approach, the incision is designed to expose the lesion on both the facial and lingual aspect. The incision extends posteriorly parallel to the anterior border of ramus and the external oblique ridge. Once the incision is given, the section is carried out to expose the entire medial aspect of the mandible. Including the retromolar area, the internal oblique ridge and the medial surface of the ramus. At least till the lingula. Here is the lingula. So it is important to expose till here, till superior aspect of lingula. So here the inferior alveolar neurovascular bundle is located and it is ligated and cut off. This procedure is done first for any mandibular lesion extending posterior to the mental foramine. Ligation of the inferior alveolar neurovascular bundle prior to the resection is important to prevent any significant intraoperative hemorrhage. So once the neurovascular bundle is ligated, the entire lesion is exposed by reflecting the myocopereostal flap on the buccal side as well. You have reflected the flap on the lingual side. Now you proceed with reflection of the flap on the buccal side also. Expose the inferior margin of the mandible. The anterior and posterior bony cuts are first outlined with a burr and then it is planned and cuts are finished by using a burr of saw blade. The cut should be through both the buccal and lingual cortices. In the tooth bearing area, you may extract one or two teeth on either side of the lesion and the vertical cuts can be performed through the extraction socket. Once the osteotomy cuts are complete, the separation of the bony cuts can be completed through osteotomy. The specimen is then separated from the bony and soft tissue attachments. The detachment of the specimen from the soft tissue attachment is similar to that performed in marginal resection. The only difference being that there is no continuity of the lower border in segmental resection. Once the specimen is completely excised, primary closure of the wound is done and intermaxillary fixation or reconstruction plate is necessary to preserve the alignment of the fragments. The extra aural approach for segmental resection can be performed with or without disarticulation. This articulation is nothing but removing the condylar segment also along with the specimen. In some cases, the surgeons do not remove the condylar if it is not involved in the disease. So the condylar stump alone is left within the fossa and the rest of the mandible is resected. Surgeons prefer to retain the condyle because of its difficulty to reconstruct the condylar head or reconstruct the temporal mandibular joint. So this diagram depicts segmental resection without disarticulation. Here the condylar stump or the condylar segment is intact. Moving on to the surgical procedure for segmental resection of the jaw with disarticulation. Here you are removing the condylar head also along with the specimen. So you opt for an extra aural approach. The incision is a combined post-ramel and submandibular incision. Post-ramel incision is Heinz incision and submandibular incision is Wrister incision. So you place a combined incision 2 cm below and parallel to the inferior and posterior border of the mandible. Dissection is carried out through the skin, subcutaneous tissue, platysma and investing layer of deep cervical fascia. And thus the inferior border of the mandible is exposed. At the inferior border of the mandible, at the inferior and posterior surface of the ramus, you identify the terugomasatric sling. The terugomasatric muscle sling is then divided at the inferior border and then you reach the massator. You know that the massator is attached to the lateral aspect of the ramus. So once you identify the massator, you perform a subperiosteal dissection of the muscle. You dissect the massator or you reflect the massator subperiosteally thus exposing the coronoid process, the sigmoid notch and the condylar head. You then determine the anterior limit of the resection. If the anterior limit is at the midline, then you are performing a hemi mandibleectomy. You complete the osteotomy cut in the anterior region and by swinging the specimen laterally, you detach it from its medial attachments. It is done subperiosteally. The medial attachments are the mylohyoid muscle and the medial terugoid. So once you complete the anterior resection, you swing the mandible or the hemi mandible laterally and free it from the medial attachments. You also free the specimen from temporalis muscle which is attached to the coronoid process, the lateral terugoid muscle which is attached to the condylar head. While performing the procedure at the condylar head region, care is taken to prevent any damage to the maxillary artery and its branches. The specimen is now completely removed and the surgical wound is irrigated. The proximal portion of the segment is smoothened to prevent any intra-oral perforation. Reconstruction plate with condylar process or processes is placed and fixed onto the proximal stump with screws. The wound is then closed in layers after proper hemostasis. These are the surgical steps in segmental resection of the jaw with disarticulation or hemi mandiblectomy with disarticulation. The next type of segmental resection is that involving the mandibular midline. This procedure is carried out for tumors which are present in the midline of anterior mandible. For this a supplemental incision is made at least 2 cm below the inferior border of the mandible. Dissection proceeds through the skin, subcutaneous tissues, the platysma and the deep cervical fascia. The incision is taken till the periosteum at the inferior border of the mandible. You continue the resection subperiosteally towards the medial aspect of the mandible to detach the left and right digastric as well as the myelohyoid muscle from the medial aspect of the mandible. So remember that from the medial aspect you need to detach myelohyoid and digastric muscles. Genioglossus and geniohyoid muscle attachments are also present at the geniotubicals. Again at the medial and inferior aspect of the anterior mandible. So in total you are removing 4 groups of muscles, digastric, myelohyoid, genioglossus and geniohyoid. The subperiosteal dissection is then carried on the buccal surface of the mandible to expose the resection area or the plant resection portion. You identify the mental nerves and they are protected. So the lateral extent of the resection is determined by the size of the tumor. You may extract one or two teeth on either side of the plant resection site and then vertical osteotomy cut is made through the extraction socket on either side. A reconstruction plate is then contoured and immediately secured with the help of screws. So immediately after resection of the specimen you need to contour the plate and fix it. This will prevent the collapse of the segments and allows the jaw function during the healing process. The oremucosa is then closed intra-oreally and you need to obtain a watertight seal. The genioglossus and geniohyoid muscles are then pulled forward with the suture which is then secured to the reconstruction plate. Extramural wound is also closed in layers. So to conclude this lecture intends to provide just the basic outline about how the surgical resection is performed for benign tumors in mandible. Every procedure described here has its own inherent difficulties and associated complications. The points you need to keep in mind for each technique are the extent of osteotomy cuts, continuity of inferior border whether it is maintained or not. The soft tissue attachments. You need to know which muscle has to be detached from each side of the mandible and whether you are retaining the condyla stump or not. Whether the procedure includes this articulation or not. Regardless of the procedure done, reconstruction, placement of terrain, extra oral pressure application and a long term follow up goes without saying for every procedure. So that's all about the mandible procedure in surgical management of jaw tumors. Thank you.