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MANAGING MANDIBLE IN ORAL CAVITY CANCERS ppt(1).pptx
- 1. MANAGING MANDIBLE IN ORAL CAVITY CANCERS Dr. D.Heber Jobson Resident-Surgical Oncology Government Royapettah Hospital Prof Subbiah et al
- 2. OVERVIEW • ANATOMY • TUMOR ENTRY ROUTES • ASSESSING BONY EROSIONS • MANDIBULAR RESECTION- TYPES • CLASSIFICATION • RECONSTRUCTION Prof Subbiah et al
- 3. ANATOMY Prof Subbiah et al
- 4. MASTICATION MUSCLES Prof Subbiah et al
- 5. BLOOD SUPPLY The blood supply to the lower gum and teeth is from the inferior alveolar branch of the internal maxillary artery and is the sole endosteal blood supply to the body of the mandible. The mandibular periosteum provides blood to the cortical bone. ENDOS TEAL PERIO STEAL Prof Subbiah et al
- 6. TUMOR ENTRY ROUTES Tumors tend to enter the mandible at the point of abutment, which in both the dentate and edentulous jaw is often at the junction of the reflected and attached mucosa. The attached mucosa with its firm collagen attachment to bone is proposed as the main route of tumour entry into the mandible in both dentate and edentulous mandibles. Prof Subbiah et al
- 7. TUMOR ENTRY ROUTES Majority of the spread to mandible occurs by direct infiltration of the tumour through alveolar ridge or lingual cortical plate. The possibility of mandibular involvement is higher in patients where tumours are located with in 1 cm of the mandible. Involvement of mandible through the canal of inferior alveolar nerve in the present study was relatively high (20%). Prof Subbiah et al
- 8. MANDIBLE INVASION PATTERNS INVASIVE EROSIVE Fingers or Islands of tumour advancing deeply into bone with no obvious osteoclastic activity. A broad advancing front with osteoclast activity and connective tissue between the tumour and bone. Large, deeply invading tumours are more likely to demonstrate an invasive pattern of spread and involve the mandible. As the depth of invasion increases, they become more invasive in character More likely gives rise to cervical metastasis with Extracapsular extension More aggressive nature • The mandible should be considered at risk at any point where tumour is in contact and this is taken into account when planning resection. • Clinical fixation of the tumour to bone is not necessary for bone invasion to occur. Prof Subbiah et al
- 9. Prof Subbiah et al
- 10. Prof Subbiah et al
- 11. • Primarily the size and extent of the tumour, dictates the pattern of spread once in bone rather than anatomical features (Inferior alveolar nerve or Periodontal ligament). • Preferential spread within the mandible via the Inferior alveolar nerve or Medullary space is rare, justifying 1 cm margins. Prof Subbiah et al
- 12. ASSESSING BONY EROSIONS • Preoperative imaging- Absence or presence of mandibular erosion, Bone destruction if present confirms tumor invasion To plan for appropriate type of resection • The anteroposterior extent of erosion (on axial images) and the height of the uninvolved segment of mandible from the inferior border (on coronal imaging) - To plan marginal mandibulectomy. Prof Subbiah et al
- 13. OPG: • For Bony invasion, Mandible height, dental anatomy and pathology • Plain radiographs do not detect initial invasion until 30 per cent demineralization has occurred- Reduced sensitivity. • Absence of radiographic findings does not rule out bone invasion. • Radionuclide bone scans often are positive before the radiographic appearance of bone destruction. Prof Subbiah et al
- 14. (A) Axial CECT showing the Puffed Cheek technique in (B) that separates the buccal and gingival surfaces with air depicting that epicenter of lesion (arrows) is in the buccal mucosa. The lesion does not abut mandible as appears in A Prof Subbiah et al
- 15. (A) Oblique MDCT reformation showing extensive mandibular erosion reaching inferior alveolar canal (arrow) (B) Large paramandibular soft tissue mass (arrow) seen on coronal reformat CECT abutting a large surface of mandible (vertical line) without eroding Prof Subbiah et al
- 16. (A) Lower GBS mass abutting mandible (arrow) (B) Coronal reformat (bone algorithm) shows subtle erosion of buccal cortex (long arrow). Short arrow shows opposite intact cortex. Yellow line shows adequate height of uninvolved mandible (at least 1cm to prevent fracture) Prof Subbiah et al
- 17. Clinical examination alone was not shown to be accurate, but periosteal stripping at the time of resection was extremely accurate. No single imaging technique will accurately predict the invasion of tumour into the mandible, but a combination of an orthopantomogram and bone scintigraphy is recommended in early invasion. Magnetic resonance imaging is more sensitive than computed tomography and therefore may be more useful if mandibular invasion requires consideration. Prof Subbiah et al
- 18. The present study showed that combined CT and MRI enabled precise analysis of mandibular invasion in oral cavity and oropharyngeal cancer. The two should ideally be associated, adhering to good practice criteria, within 4 weeks before surgery. This optimization of radiologic assessment allows treatment to be adapted, avoiding over-resection and improving postoperative course and limiting long-term sequelae. Prof Subbiah et al
- 19. MANDIBLE IMAGING SENSITIVITY SPECIFICITY CLINICAL EXAMINATION 82 61 OPG 76 81 COMPUTED TOMOGRAPHY 75 86 MRI 85 72 SINGLE PHOTO EMISSION COMPUTED TOMOGRAPHY 97 65 BONE SCINTIGRAPHY 93 74 Prof Subbiah et al
- 20. MANDIBULAR RESECTION • RIM/MARGINAL • SEGMENTAL • PERIOSTEAL RESECTION Prof Subbiah et al
- 21. RIM/MARGINAL MANDIBULECTOMY • INDICATIONS No Bony Erosion/Superficial Erosion Tumor close to the mandible to achieve adequate margins Minimum Periosteal involvement T1/2 tumors with adequate bony height • CONTRA-INDICATIONS Gross Bony erosion Post-RT/Edentelous Mandible Gross Periosteal involvement/Paramandibular disease Prof Subbiah et al
- 22. TYPES: • Horizontal • Vertical • Oblique Prof Subbiah et al
- 23. • To resect the alveolar process, the lingual plate of the mandible, or a combination of the alveolar process and the lingual plate of the mandible for tumors of the anterior oral cavity • For lesions adjacent to the retromolar trigone, Anterior aspect of the ascending ramus of the mandible including the coronoid process and the adjacent alveolar process of the body of the mandible, are resected. • Reverse marginal mandibulectomy -Indicated in patients with soft tissue disease such as fixation of Prevascular facial lymph nodes to the lower cortex of the mandible. Prof Subbiah et al
- 24. Prof Subbiah et al
- 25. Prof Subbiah et al
- 26. • No Right angled cuts-Excessive stress- spontaneous fracture • Smooth curve cuts- canoe shaped to evenly distribute the stress Prof Subbiah et al
- 27. • APPROACH PERORAL-Early superficial cancer, Anterior lesion, Adequate mouth opening, Accessible CHEEK FLAP-Large cancers, Posteriorly placed, Deep infiltrative, Bony resection Prof Subbiah et al
- 28. Prof Subbiah et al
- 29. Prof Subbiah et al
- 30. SEGMENTAL MANDIBULECTOMY INDICATIONS: • Gross bony invasion • Invasion of Inferior alveolar nerve • Invasion of Medullary canal • Significant Paramandibular spread • Primary Mandibular tumors • Marginal Mandibulectomy not feasible Prof Subbiah et al
- 31. • Posterior segmental • Lateral Segmental • Anterior segmental • Hemimandibulectomy • Arch preserving Hemimandibulectomy • Extended Hemimandibulectomy Prof Subbiah et al
- 32. CLASSIFICATION OF THE MANDIBULAR DEFECT Urken et al.- 1991 Based on mandible and soft tissue defect. The mandibular defect can be classified as H, C, L: H – lateral defects of any length including the condyle L – as above but the condyle not included C – entire central segment from lower canine to canine. The soft tissue defect can be classified as none, skin, mucosal and through and through. Prof Subbiah et al
- 33. Boyd et al.’s classification - Three upper case and three lower case letters. • For a bony defect, it is similar to the above classification. • A combination of letters is possible, for example a defect from angle to angle of the mandible is LCL. • For a soft tissue defect: o – neither skin or mucosa affected s – skin m – mucosa. A through and through defect - sm Prof Subbiah et al
- 34. Boyd et al Prof Subbiah et al
- 35. • Based on four corners of the mandible- Two angles and Two canines: class I (Lateral) class II (Hemimandibulectomy) class III (Anterior) class IV (Extensive). classes (Ic, IIc, and IVc) include Condylectomy. • The increasing defect class relates to the size of the defect, osteotomy rate, and functional and aesthetic outcome, and could guide the method of reconstruction. Prof Subbiah et al
- 36. PROBLEMS WITH MANDIBULAR RESECTION Occlusion Speech Swallowing Mastication Oral competence Tongue Fall and Mobility Appearance Prof Subbiah et al
- 37. ANATOMICAL CONSIDERATIONS AND MANDIBLE RECONSTRUCTION The cosmetic deformity and functional loss that occur after mandibular resection depends on the size and location of the segmental defect. • Anterior defect - Greater the deformity and loss of function. • (Andy Gump Deformity) • Posterior defect- better tolerated but result in malocclusion in a dentate patient. • Lateral defect (Posterior to the mental foramen)- Deviation of the mandible towards the resected side due to the unopposed pull of the remaining muscles of mastication, soft tissue contracture and scar formation. – Dental occlusion affected. Prof Subbiah et al
- 38. NO BONY RECONSTRUCTION • Use of alloplastic materials to reconstruct the mandible. • Ideal alloplastic material - Biocompatible and withstand the forces sustained by the mandible in mastication. • Medical polymers, ceramics and metals. • Vitallium and stainless steel in the form of a plate- Susceptible to screw loosening and fracture. • THORP (Titanium hollow osseointegrated reconstruction plate) plate withstands masticatory forces and plate fracture is rare. • Plate exposure through the external skin or into the mouth. • Improving the soft tissue vascularity with free tissue transfer or Pedicled flaps reduces the complications. . Prof Subbiah et al
- 39. BONE GRAFTS +/-SOFT TISSUE COVER Free bone grafts Bardenheuer in 1881. Block grafts or particulate Cancellous bone in metallic trays. • Non-Vascularised Bone Grafts: Defects smaller then 5 cm in length in healthy surrounding soft tissue and not to be treated with postoperative radiotherapy. Autologous, Allogenic, Xenografts. Autologous grafts have osteogenic potential. Others - Scaffolding over which the patient’s cells can induce bone formation. • Bony Free Flap: Longer defects, Require Radiation. Prof Subbiah et al
- 40. DISTRACTION OSTEOGENESIS Growing new bone by distraction (stretching) of pre-existing bone. STAGES: 1. Osteotomy – cuts through the bony cortex. 2. Latency – Time between osteotomy and the start of distraction- formation of a primitive callus. 3. Distraction – The callus is stretched at a rate of 1 mm per day. I Less than 0.5 mm per day - Early fusion. Greater than 1.5 mm per day - fibrous union. Optimum rate - 1.0 mm per day, divided into four movements of 0.25mm per day. 4. Consolidation – New bone is stabilized for up to 4 weeks. The initial bone formed is non-lamellar and gradually gets replaced by lamellar bone. Distraction Devices- Intraoral or Extraoral. Prof Subbiah et al
- 41. DENTAL IMPLANTS • For restoring Mandibular continuity and dentoalveolar structure reconstruction. - Reduced alveolar bone height -Poor lingual and labial sulci -Reduced Tongue mobility -Radiotherapy- Dry mouth. All these factors make conventional dentures difficult to wear. Prof Subbiah et al
- 42. OSSEOINTEGRATION • Incorporation of metal into living bone. • The bone is able to remodel under loading of the implant. • The implants are coated with titanium oxide and contamination must be avoided at the time of placement. • Integration rates are more predictable if loading is delayed. The use of hyperbaric oxygen in irradiated patients may increase implant survival rates. Prof Subbiah et al
- 43. TEMPEROMANDIBULAR RECONSTRUCTON • Mandibular condyle should be preserved if possible without compromising tumor resection. • If preserved, the new bone must be fixed to it. • Condyle must be positioned in the glenoid fossa at its preoperative position. • If condylar head needs to be sacrificed, the bony flap can be placed directly into the glenoid fossa. • Fibula- ideal bony flap for temperomandibular reconstruction. • If dentate, a prosthetic condylar head be used within a bony flap that provides a more predictable occlusion Prof Subbiah et al
- 44. THANK YOU Prof Subbiah et al
Editor's Notes
- The mandible is a membranous bone. It has a horseshoeshaped body and a pair of rami. The body of the mandible meets the ramus on each side at the angle of the mandible The upper part of the mandible from the midline to the angles is the alveolar process. This bone carries the teeth. The ramus is vertically placed and forms the coronoid process and the mandibular condyle. The condyle articulates with the skull base at the mandibular fossa to form the temperomandibular joint. This is a synovial joint. The dental sockets on the alveolar process of the mandible and maxilla are covered by attached buccal mucosa that is reflected from the lips, the floor of the mouth, and the hard palate. The nerve supply to the lower gum and dentition is from the inferior alveolar nerve (the mandibular branch of the trigeminal nerve [V3]). The nerve enters the mandibular canal on the medial aspect of the ramus of the mandible and exits at the mental foramen on the lateral surface of the body of the mandible. T
- Various muscles (the elevators and depressors of the mandible) are attached to the mandible at a variety of sites. They are responsible for the complex movements required of the mandible in mastication, swallowing and speech. As the mandible projects anteriorly from its articulation with the skull base, a cantilever system with a fulcrum at the temperomandibular joint is created. This requires the mandible to sustain significant forces particularly in mastication. Tensional forces are created at the upper border and compressional forces at the lower border. Whatever mode of reconstruction is used, it must be able to withstand these considerable forces Â
- Sharpeys fibres binding the attached mucosa to the bone Sharpey's fibres (bone fibres, or perforating fibres) are a matrix of connective tissue consisting of bundles of strong predominantly type I collagen fibres connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae of bone tissue
- Therefore it is recommended that before a decision is taken to preserve the mandible it should be thoroughly screened for possible involvement.
- The proximity or direct extension of a primary tumor of the oral cavity to the mandible requires appropriate radiological studies to establish the presence and extent of bone involvement.., but they seldom provide accurate information regarding the extent of bone invasion. Bone scans also may be positive in nonneoplastic conditions, such as inflammatory lesions. Plain radiographs of the mandible in the antero-posterior and oblique views are not satisfactory as a routine screening test to establish or rule out bone destruction. Erosion is subtle or gross (buccal, occlusal, and/or lingual cortices and if the marrow and inferior alveolar canal are invaded). Imaging should record sparing of the condyloid process and posterior segment of the mandible which helps plan reconstruction, necessary after segmental mandibular resection.
- CT criteria for mandibular bone invasion comprised: cortical erosion, cortical rupture, mandibular nerve canal infiltration or periosteal reaction; MRI criteria comprised: mandibular nerve canal infiltration, low-intensity lesion on T1 with contrast uptake (indicating replacement of medullary bone by tumor) or high-intensity lesion on T2
- The accuracy of clinical examination, peroperative periosteal stripping and imaging techniques in predicting tumour invasion of the mandible in oral cancer so far reported have been compared according to their specificity and sensitivity.
- surgical resection of the mandible becomes necessary when a primary malignant tumor of the oral cavity directly extends to the gingiva over the alveolar process or infiltrates into the mandible. If the tumor extends directly from the alveolar process to the cancellous part of the mandible or if contiguous tumor infiltration to the lingual or lateral cortex of the mandible is present, a segmental mandibulectomy becomes necessary
- As the lingual plate is weaker than the buccal plate, an isolated buccal plate excision may not withstand subsequent weight bearing and the bone may fracture. Hence isolated buccal plate excision is risky in buccal mucosa lesions
- The theory of preferential route of tumor entry through the inferior alveolar nerve has been refuted by multiple studies; hence it is no longer advocated to include the inferior alveolar nerve up to the skull base with a rim resection
- The exposed bone following a marginal mandibulectomy is covered by primary mucosal closure between the mucosa of the tongue or floor of the mouth to the mucosa of the cheek, a split thickness skin graft, or a radial forearm free flap. However, it must be remembered that primary closure will eliminate the lingual or the buccal sulcus, rendering fabrication of a removable denture exceedingly difficult. Alternatively, a skin graft can be applied directly over the marginally resected mandible, which would permit retention of the sulci and the ability of the patient to wear a partial denture that can be clasped to the remaining teeth. In edentulous patients, wearing a denture over a marginally resected mandible is very difficult. In such a situation, osseointegrated implants with a fixed denture should be considered.
- Marginal Mandibulectomy for Ca FOM through a Lower cheek flap approach
- Midline split-lesion away from commissure, maintains competence Angle split- lesion close to commissure, overlying skin needs to be excised.
- Not only the size and location of the mandibular defect should be assessed, but also the associated soft tissue deficit. Only a thorough understanding of the defect allows optimal reconstruction  The size and location of the soft tissue deficiency, the vascularity of the remaining soft tissues, the presence of infection and whether the tissues have been irradiated will determine the best mode of reconstruction..
- Occlusion- bony defect deviation Speech- articulation Swallowing- oral phase Mastication- disruption of muscles Oral competence-integrity of lip and cheek Tongue Fall and Mobility- genial complex, extent of excision Appearance- resection extent
- The aims of mandibular reconstruction are to restore form and function, cover any defects causing minimal morbidity, and maximizing quality of life. This requires thorough defect analysis, assessment of all donor sites, knowledge of all the modes of reconstruction and working in a multidisciplinary environment. It is important that every unit treating patients with mandibular tumours possesses the full repertoire of reconstruction so the most suitable modality is chosen for each patient. Free tissue transfer is now the gold standard in reconstruction of the mandible. It is an extremely reliable method of reconstruction, particularly in a hostile recipient bed. However, it requires specialized teams and significantly longer operating times. Postoperative morbidity and possible loss of form and function at the donor site are important considerations
- Kiyokawa et al. reconstructed the oro–mandibular complex using a pectoralis major flap with a metal plate in seven patients with no complications. Bhathena and Kavarana used a sialastic mandibular implant for mandibular reconstruction in 69 patients. Only 30 per cent of the implants were retained for greater than one year. Chemoradiotherapy was one of the major determinants for extrusion. Okura et al. 8 in a series of 100 patients reconstructed mandibular defects with bridging plates. The plate survival at five years was 62 per cent. Anterior defects and radiotherapy were major determinants for survival. Anterior mandibular defects are much more likely to fail than posterior ones. Ninety-two per cent of reconstruction with plates is successful in lateral defects but only 30 per cent with anterior ones. It is also argued that patients who require mandibular reconstruction for advanced cancers will die of their disease within two years and so the use of alloplastic materials is recommended. Shiptzer et al. showed good results of mandibular reconstruction with just plates. There was no plate exposure, extrusion or fracture in 83 per cent of their sample one year and 72 per cent at two years  As the risk of initial complications with alloplastic reconstructions is less than that with more complex reconstructions, delays in starting adjuvant chemoradiotherapy are less. There is also no evidence that alloplastic metals are responsible for radiation shielding in patients. Lindquist et al. concluded that functional and aesthetic results were excellent in their series of 34 patients when reconstruction plates were used. Blackwell et al. in a series of 17 patients abandoned using soft tissue flaps with THORP plates even for lateral defects as the risk of reconstructive failure in their series was as high as 40 per cent. Kim et al. presented 41 cases reconstructed with AO plates. Twenty-two per cent of patients required plate removal but the incidence varied as to the location of the defect – 52 per cent of anterior, 12 per cent of lateral and 8 per cent of condylar and ramus defects. Wei et al. looked at 80 patients reconstructed with a reconstruction plate and a soft tissue flap. Thirty-one per cent of surviving patients had required secondary surgery for plate exposure, soft tissue deficiency, intraoral contracture, trismus and lack of gingivolabial sulcus. Ryu et al. showed that significantly more mandibular plates were lost when the patient had received radiotherapy in the postoperative period. The patient’s quality of life and oral rehabilitation does not appear to be related to the quantity of mandible resected but on the amount of associated tongue resection. Although some success has been achieved with alloplastic materials, the general consensus among reconstructive surgeons is that the potential problems outweigh any benefits and so this technique is reserved for patients with medical comorbidities
- Owing to the risk of infection, allogenic and xenografts are rarely used. The use of trays packed with cancellous bone was popularized in the 1960s. However, they were associated with very high failure rates due to infection and graft extrusion. Failure rates of up to 50 per cent are described when grafts are placed in irradiated tissue, or contamination of the graft with oral microbials occurs.
- Ilizarov53 applied the principles of distraction osteogenesis to treat thousands of patients with limb defects. Kuriakose et al. 54 treated four patients with distraction with defects between 3.5 and 6.5 cm. Extraoral devices leave unsightly facial scars. The efficacy of distraction in previously irradiated mandible has been shown by Gantous et al. Rubio-Bueno56 distracted five patients with intraoral distractors for segmental defects of 35–80 mm. They were successful in three of the five patients. In one patient there was intraoral exposure of the distractor and one patient died. Distraction is likely to be better for dental prosthesis and implants in view of the better bone quality, quantity and the ability to produce normal mucosa. However, it is time-consuming with occlusal disturbance likely as it is difficult to get all the vectors of movement right. Although distraction has been shown to be possible in the irradiated canine model, its use in patients who have received radiotherapy is still in questio
- For the complete rehabilitation of a patient after mandibular resection, mandibular continuity needs to be restored and the dentoalveolar structures reconstructed. Any patient who has undergone resection of the mandible with or without soft tissue resection has disturbed internal anatomy and altered sensation despite reconstruction. The alveolar bone height is reduced with poor lingual and labial sulci and the tongue anatomy and mobility may also be reduced. May also have received radiotherapy and suffering from a dry mouth. All these factors make conventional dentures difficult to wear.
- The soft tissue around which the implant exits the bone has to be keratinized and attached mucosa otherwise chronic inflammation may result. Although implants may be loaded immediately, integration rates are more predictable if loading is delayed.