NEET MDS Lessons
Oral Pathology
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.
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Blood: Aneurysmal bone cyst, Vascular lesion, Vessel puncture.
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Air: Traumatic bony cyst (Simple Bone Cyst/Hemorrhagic Bone Cyst), Maxillary sinus.
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Chocolate Colored Fluid: Warthin's Tumor (salivary gland cyst).
- Nasopalatine cyst is the most common non-odontogenic cyst
- Globulomaxillary cyst entity is controversial - many consider it a variant of lateral periodontal cyst
- Median mandibular cyst is extremely rare - always consider other diagnoses first
- Nasolabial cyst is the only one with no radiographic features
- 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)
Gemination
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Attempted division of a single tooth germ before calcification.
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Results in two crowns (complete/incomplete) with one root and canal.
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Tooth count remains normal.
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Difficult to differentiate from fusion with a supernumerary tooth.
Twinning
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Complete division of a single tooth germ.
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Results in one normal + one supernumerary tooth.
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Tooth count is more than normal.
Fusion
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Union of two separate tooth germs.
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If before calcification → single large tooth.
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If after calcification → roots fused, crowns may be separate.
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More common in deciduous teeth.
Concrescence
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Union by cementum only.
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Occurs after root formation.
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Common in maxillary molars.
Intraepithelial Bulla
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Location: Within the epithelium
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Associated Conditions:
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Herpes simplex
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Herpes zoster
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Chicken pox
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Pemphigus
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Hailey-Hailey disease (Familial benign pemphigus)
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Epidermolysis bullosa (dystrophic recessive form)
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Oral lesions of erythema multiforme
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Subepithelial Bulla
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Location: Below the epithelium
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Associated Conditions:
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Pemphigoid
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Bullous pemphigoid (most common subepithelial blistering disease)
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Bullous lichen planus
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Dermatitis herpetiformis
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Epidermolysis bullosa
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Skin lesions of erythema multiforme
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Schilling Test: Done to identify the deficiency of either extrinsic (dietary vitamin B12) or intrinsic factor involved in Pernicious Anemia.
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Fanconi's Syndrome: Associated with Aplastic Anemia.
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"Safety-Pin" Cells: Characteristic finding in Thalassemia / Erythroblastic Anemia.
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Radiographic Features of Anemias:
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"Salt and Pepper" effect (Intraoral Periapical Radiograph): Found in Cooley's Anemia (Thalassemia) and Sickle Cell Anemia.
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"Hair-on-End" pattern (Skull Radiograph): Found in Thalassemia, Sickle Cell Anemia, Congenital Hemolytic Jaundice, Chronic Iron Deficiency Anemia.
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"Rh Hump" (Erythroblastosis Fetalis): Describes a ring-like defect.
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Plummer-Vinson Syndrome: Associated with Iron Deficiency Anemia.
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Chediak-Higashi Syndrome: Giant abnormal PAS positive granules found in peripheral circulating leukocytes are basically altered lysosomes.
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Philadelphia Chromosome: Translocation of chromosomal material from chromosome 22 to chromosome 9; found in Chronic Myeloid Leukemia (CML).
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Most Common Benign Odontogenic Tumor: Odontoma (Ameloblastoma is second).
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Adenoid Cystic Carcinoma vs. Adenomatoid Odontogenic Tumor (AOT):
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Adenoid Cystic Carcinoma: Salivary gland malignancy.
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Adenomatoid Odontogenic Tumor (AOT): Benign odontogenic tumor. Do not confuse them.
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Liesegang Rings: Can be seen in CEOT/Pindborg's Tumor (primarily) and AOT (rarely).
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Amyloid-like Deposits: Characteristic feature of CEOT (Calcifying Epithelial Odontogenic Tumor).
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Duct-like Structures: Seen in AOT (Adenomatoid Odontogenic Tumor).
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Granular Cell Ameloblastoma: Granules are lysosomal aggregates.