Predisposing factors:

1. Reduced host resistance:

• DM
• TB
• Immunosuppression/ HIV
• Leukemia
• Chronic alcoholism
• Malnutrition
• Anemia

2. Reduced jaw vascularity:

• Radiation
• Osteoporosis
• Osteopetrosis
• Fibrous dysplasia
• Bone malignancy
• Peripheral vascular disease

Pathogenesis

• Pus accumulates in marrow spaces
• Increases intramedullary pressure
• Compress vasculature
• Decreased blood supply
• Decreased nutrients and hypoxia
• Necrosis of bone
• Sequestrum
• Spreads to subperiosteal area
• Perforation
• Fistula to skin and oral mucosa

Microbes

1. G+ve = S. aureus, S. albus, Hemolytic strep
2. G-ve = Klebsiella, Pseudomonas, Proteus, E. coli
3. Anaerobes = Pepto-streptococcus, bacteroid, fusobacteria

Histopathology

• Localized pus + lymphocytes + plasma cells
• Dead bone – empty lacunae ( no osteoclasts)
• Pus found in medulla
• Periosteum distended by pus
• Osteoblastic and osteoclastic activity
• Involucrum – New bone
• Sequestrum – Dead bone
• Onion skin appearance (in chronic)

Clinical classification

1. Anatomical location:

• Intramedullary
• Subperiosteal
• Periosteal

2. Duration & severity:

• Acute
• Chronic

3. Presence/ absence of suppuration:

• Suppurative:
  • Acute
  • Chronic
    • 1ry (denovo)
    • 2ry (low grade infection)
  • Infantile

• Non suppurative:
  • Chronic – Moth eaten on x-ray
  • Osteoradionecrosis
  • Garre’s osteomyelitis – Onion skin on x-ray
    • Chronic osteomyelitis with proliferative periostitis
    • Young people
    • Increased reactive new bone formation
  • Atypical osteomyelitis:
    • TB
    • Syphilis
    • Actinomyces

• Others:
  • Chronic diffuse sclerosing – Old people, super infection of florid COD
  • Chronic focal sclerosing – Young people with carious teeth

Clinical features

• Pain
• Swelling
• Pyrexia
• Lymphadenopathy
• Periosteum distended with pus
• Discharging sinus
• Rampant caries
• Periodontitis
• Anesthesia, paresthesia of lower lip
• Teeth may become mobile, tender
• Pus exudes from sockets or gingival margin
• Difficult to open mouth – due to edema of muscle

Management

1. Early lesion:

• Basic incision and drainage
• Supportive therapy: Rehydrate, nutritional diet, hyperbaric O₂

2. Severe lesion:

• Antibiotic
• Surgical debridement
• Irrigation
• Sequestrectomy/ resection ± decortication

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Acute osteomyelitis

Source:

• Periapical inflammation
• Open fracture (involving PDL socket/ penetrating contaminated injury)
• ANUG
• Pericoronitis

Predisposing factors:

• Reduced host resistance
• Paget’s disease
• Radiation damage
• Trauma including gunshot wounds

Epidemiology:

• Adult males (Fights)
• Mandible (has low blood supply)

Radiology:

• Loss of trabeculae pattern
• Areas of radiolucency – bone destruction
• Moth eaten appearance
• 30% osteolysis needed for x-ray changes

Complications:

• Anesthesia of lower lip
• Pathological fractures – rare
• Chronic osteomyelitis
• Cellulitis/ septicemia in immunocompromised patients

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Chronic non-suppurative osteomyelitis

Etiology:

• Acute osteomyelitis
• Radiation
• Persistent low-grade infections

Predisposing factors:

• Similar to acute
• Local bone sclerosis
• Localized reaction of bone to inflammation or infection

Histology: Marrow spaces devoid of pus and bacteria

Types:

Type	Acute	Chronic	Garre’s	Chronic diffuse sclerosing	Chronic focal sclerosing
Etiology	Staph, strep	Staph, strep	Staph, strep, Sequel of tooth abscess/extraction	Low grade infection, pulpitis, PDL disease	Low grade focal bone irritation eg. pulpitis
Clinical	Pain, pyrexia, lymphadenopathy, leukocytosis	Variable pain, swelling, discharging sinus	Lower molars of children, adolescents	Pain, discharging sinus, usually mandible	Asymptomatic, found on routine exam
X-ray	No change	Moth eaten radiolucency	Mottled radiolucency, onion skin pattern	Generalized opacification	Opaque mass at root apex
Sclerosis			Periosteal reaction at lower border of mandible	Periapical/ periodontal	Periapical, non vital tooth
Age			Adolescents	Adult	Children and young adults
Histopathology			Parallel layers of cellular woven bone, small sequestra	Sclerosing + remodeling, scant marrow space, adjacent inflammation	Dense sclerotic

NB: Sequestra separate spontaneously or incorporated into healing bone

Complications:

• Spread of infection in abnormal bone (eg. Paget’s disease)
• Infection with low virulence organisms/inadequate antibiotic treatment – long standing osteomyelitis with sclerosis of viable bone

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Bisphosphonate induced osteomyelitis

• Bisphosphonate suppresses osteoclast activity and reduces blood flow
• Therefore inhibits bone resorption
• Bisphosphonates lessens the bone destruction (caused by malignancy) but there is an increased susceptibility to ischemia
• High dose can cause osteonecrosis

• Therefore before bisphosphonate is administered, the following should be considered:

1. Potential problems to be eliminated
2. At risk patient should be identified by history taking and predisposing factors
3. Surgical procedures should be avoided for as long as possible after administration
4. Extractions should be followed by antibiotics and mouth rinse until socket has healed

Risk factors:

• IV high dose bisphosphonate treatment usually for bone metastases/hypercalcemia of malignancy
• Radiotherapy to head and neck
• Immunosuppression from chemotherapy/steroids
• Anaemia
• Dental surgery/sepsis, ill fitting dentures and poor oral hygiene
• Female patient
• Elderly patient
• Smoking

Clinical:

• Non healing extraction socket/asymptomatic exposed bone
• Do not respond to conservative treatment
• Extractions could precipitate onset
• Once infection is established – acute/chronic osteomyelitis may ensue – this depends on both virulence or organism and host resistance
• Because bisphosphonate reduce bone turnover, sequestra develop very slowly

Complications:

• Oroantral and cutaneous fistulae
• Suppuration

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Osteoradionecrosis

• Osteomyelitis caused by radiotherapy
• Radiotherapy causes narrowing of blood vessels therefore decreased blood supply to bone
• Diagnosis based on history of radiotherapy
• Once infection develops – course is similar to conventional osteomyelitis
• But bone is more fragile due to radiotherapy – therefore infection more extensive, and sequestration is delayed

Complications:

• Extraoral sinuses
• Pathological fracture
• Pain that is difficult to manage (even when using opioids)

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