NEET MDS Lessons
Oral Pathology
Osteomyelitis
Osteomyelitis is an extensive inflammation of a bone. It involves the cancellous portion, bone marrow, cortex, and periosteum
Conditions that alter HOST IMMUNITY
Leukemia, Severe anemia, Malnutrition, AIDS, IV- drug abuse, Chronic alcoholism, Febrile illnesses, Malignancy, Autoimmune disease, Diabetes mellitus, Arthritis, Agranulocytosis
Conditions that alter vascularity of bone
Osteoporosis, Paget’s disease, Fibrous dysplasia, Bone malignancy, Radiation, Virulence of the organisms
Certain organisms precipitate thrombi formation by virtue of their destructive lysosomal enzymes.
Organisms proliferate in enriched host medium while protected from host immunity.
Etiology
- Odontogenic infections
- Trauma
- Infections of oro facial region
- Infections derived from hematogenous route
- Compound fractures of the jaws.
PATHOGENESIS
DEV . OF INFECTION --> BACTERIAL INVASION --> PUS FORMATION --> SPREAD OF INFECTION --> INCREASED INTRAMEDULLARY PRESSURE , BLOOD FLOW , OSTEOCLASTIC ACTIVITY --> INFLAMMATORY RESPONSES --> INCREASED PERIOSTEAL PRESSURE --> PROCESS BECOMES CHRONIC GRANULATION TISSUE FORMATION --> LYSIS OF BONE --> SEQUESTRUM FORMATION
Classification
Classification based on clinical picture, radiology, and etiology
Suppurative osteomyelitis
I. Acute suppurative osteomyelitis
II. Chronic suppurative osteomyelitis
– Primary chronic suppurative osteomyelitis
– Secondary chronic suppurative osteomyelitis
III. Infantile osteomyelitis
Nonsuppurative osteomyelitis
I. Chronic sclerosing osteomyelitis
– Focal sclerosing osteomyelitis
– Diffuse sclerosing osteomyelitis
II. Garre's sclerosing osteomyelitis
III. Actinomycotic osteomyelitis
IV. Radiation osteomyelitis and necrosis
Osteoradionecrosis
Clinical features
A reduction in vascularity, secondary to endarteritis obliterans, and damage to osteocytes as a consequence of ionising
Radiotherapy can result in radiation-associated osteomyelitis or Osteoradionecrosis. The mandible is much more commonly affected than the maxilla, because it is less vascular. Pain may be severe and there may be pyrexia. The overlying oral mucosa often appears pale because of radiation damage. Osteoradionecrosis in the jaws arises most often following radiotherapy for squamous cell carcinoma.
Scar tissue will also be present at the tumour site, often in close relation to the necrotic bone.
Radiology
Osteoradionecrosis appears as rarefying osteitis within which islands of opacity (sequestra) are seen. Pathological
fracture may be visible in the mandible.
Pathology
The affected bone shows features similar to those of chronic osteomyelitis. Grossly, the bone may be cavitated
And discoloured, with formation of sequestra.
Acute inflammatory infiltrate may be present on a background of chronic inflammation, characterized by formation
Of granulation tissue around the non-vital trabeculae.
Blood vessels show areas of endothelial denudation and obliteration of their lumina by fibrosis.
Small telangiectatic vessels lacking precapillary sphincters may be present.
Fibroblasts in the irradiated tissues lose the capacity to divide and often become binucleated and enlarged.
Management
Prevention of Osteoradionecrosis is vital. Patients who require radiotherapy for the management of head and
neck malignancy should ideally have teeth of doubtful prognosis extracted at least 6 weeks prior to treatment.
The dose of radiation,
The area of the mandible irradiated and
the surgical trauma involved in the dental extractions.
Surgical management of Osteoradionecrosis is similar to osteomyelitis.