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.

1. Nasopalatine cyst is the most common non-odontogenic cyst
2. Globulomaxillary cyst entity is controversial - many consider it a variant of lateral periodontal cyst
3. Median mandibular cyst is extremely rare - always consider other diagnoses first
4. Nasolabial cyst is the only one with no radiographic features
5. All these cysts are developmental in origin

Quick Facts for MCQs:

• Oval + Maxillary midline = Nasopalatine cyst
• Pear-shaped + Between teeth = Globulomaxillary cyst
• Soft tissue swelling + No X-ray changes = Nasolabial cyst
• Mandibular midline + Rare = Median mandibular cyst

MEMORY AIDS

"NASAL" for Nasopalatine Cyst:

• Non-odontogenic (most common)
• Anterior maxilla
• Spacing of centrals
• Above/between central incisors
• Location: incisive canal

"PEAR" for Globulomaxillary:

• Pear-shaped (inverted)
• Enlarges slowly
• Adjacent to lateral incisor & canine
• Root divergence

"SOFT" for Nasolabial:

• Soft tissue cyst
• Obstruction of nose
• Fold involvement (nasolabial)
• Tissue only (no bone involvement)

• Cheiloscopy: The examination of lip prints.

• Gustafson's Method for Age Estimation: Includes assessment of:

  • Amount of occlusal attrition

  • Secondary dentine deposition (coronal)

  • Periodontal attachment loss

  • Cementum apposition at root apex

  • Root resorption at apex

  • Dentine translucency

• Calcifying Odontogenic Cyst (COC) / Gorlin Cyst: Characterized by Ghost Cells.

• Aneurysmal Bone Cyst (ABC): Associated with a "blood-soaked" appearance on gross examination.

• Radicular Cyst - Common Site: Maxillary anterior teeth (due to higher incidence of trauma).

• Odontogenic Keratocyst (OKC) / Keratocystic Odontogenic Tumor (KCOT):

  • Most common site: Posterior mandible (similar to ameloblastoma).

  • Expansion: Tends to expand antero-posteriorly; buccal and lingual expansion seen in late stages.

  • Basal layer histology: Tall columnar cells with palisaded nuclei – "row of tombstones" or "picket fence appearance."

  • Classification: Now considered a benign odontogenic neoplasm (KCOT) in recent WHO classifications.

Miescher Cheilitis

• Definition: Granulomatous inflammation confined to the lip

Melkersson–Rosenthal Syndrome

Triad:

1. Facial palsy
2. Cheilitis granulomatosa
3. Fissured tongue

Ascher Syndrome

Triad:

1. Double lip
2. Blepharochalasis
3. Nontoxic thyroid enlargement

Double Lip

• Appearance: Cupid's bow

• Rapid drop in plaque pH after sugar
• Critical pH for enamel demineralization: ~5.5
• Caries-prone individuals:
  • Lower plaque pH
  • Higher Lactobacillus counts

Research Highlights

• Stephan: Rapid pH drop post-carbohydrates
• Caries-free pH: ~7.1
• Caries-active pH: ~5.5
• Maxillary anterior teeth: Greater drop than mandibular
• Stratfors: Lower pH ↔ higher Lactobacillus; plaque buffers better than saliva