To understand Sequestration and Sequestrectomy you need to first know what is Sequestrum – It is a piece of dead or necrosed bone or tissue formed within a diseased or injured bone, separated from the the normal or healthy bone by the process of necrosis. It is usually seen in Osteomyelitis or Osteoradionecrosis. The Sequestrum is usually surrounded by infected exudate.
It is the process of separating necrotic bone from living or healthy bone. A sequestrun is formed due to the resorption of living bone bordering the dead or necrotic bone. Formation of a sequestrum is seen more commonly in staphylococcal infections which is seen to cause resorption of bone while Streptococci infections lead to rarefaction.
Radiographic features of Sequestrum:
The Sequestrum is radiopaque in appearance as calcium is deposited in the infected tissue along with formation of periosteal bone which is known to strengthen the bone giving it a radiopaque appearance in the radiograph.
Treatment of Sequestrum:
Treatment of Sequestrum is planned only after the clinical and Radiographic diagnosis is done. Surgical treatment is required to remove a sequestrum which is done in two procedures – Sequestrectomy and Saucerization. These surgical procedures are performed only after the acute phase of infection has subsided and chronic stage has begun which gives better prognosis.
It is the surgical removal of a sequestrum using an intraoral or extraoral approach depending on the size of the lesion and its location. A pre-operative radiograph is a must to determine the exact extent and location of the necrotic bone to determine the approach. Most preferred approach is Intra-oral as this prevents the complications seen during radiation therapy in later stages of treatment.
Procedure: An Incision is given either Intraorally or Extraorally depending on the extent and location of the sequestrum. An incision on the alveolar ridge is given to gain access to the entire lesion to help in removing it in entity. The soft tissue connection with the bone is removed using a blunt instrument to gain access to the sequestrum which is then isolated from the surrounding healthy tissue and removed. Roungers are used to break and remove any remaining infected or necrotic bone.
In some cases, the sequestrum is enclosed in a involucrum, in such case a window in the bone should be drilled to remove the entire involucrum. It is very important to remove all necrotic bone and to identify the border of healthy bone we should look at bleeding during drilling, healthy bone bleeds while necrotic bone does not. the healthy bone should be drilled at least 1.5 cm to make sure that there are no remnants of necrotic bone left out. The bony defect left after removal of sequestrum should br packed with iodoform guaze, moistened with compound tincture of benzoin and the wound irrigated daily.
It is the Surgical excavation of tissue – soft tissue, muscle, bone and teeth which include the wound and its surrounding tissue resulting in a shallow depression to help in drainage of Infected wound. Most commonly done in Mandible and less common in Maxilla. In some cases Saucerization is performed in combination with sequestrectomy and in such cases the incision is made in such a way as to include the entire infected portion, bone extending through the periosteum. After removal of the sequestrum, the sharp bony borders of the cavity are trimmed using a bone rounger to remove any sharp or pointy borders and surrounding made smooth using bone files or burs. The complete cortex and seruestra should be removed. The wound should be packed with sterile guaze and antibiotic ointment place with sutures given loosely, this dressing should be replaced every 3-7 days until the surface of the bone is epithelialized. Sutures are placed if required or the wound can be left alone with just packing of gauze until the suppuration subsides.
Image: Tuberculous Osteomyelitis affecting Periodontium: A rare case report – jisponline.com (Journal of Indian Society of Periodontology)