Ameloblastic Tumours Overview

Ameloblastic Fibroma (AF)

• Benign odontogenic tumour, mixed epithelial and ectomesenchymal.
• Lacks dental hard tissue.
• Typically in the second decade of life.
• Painless, slow-growing swelling or missing tooth; interferes with adjacent tooth eruption.
• Posterior mandible or maxilla location.
• Multilocular, smooth, well-defined, corticated outline on radiographs.
• Radiolucent with internal radiopaque septa.
• Jaw expansion and tooth displacement.
• Composed of branching odontogenic epithelium in ectomesenchymal stroma, resembling budding but more developed tooth germs.
• Palisaded ameloblast-like cells with reverse polarity (nucleus away from basement membrane).

Ameloblastic Fibrodentinoma (AFD) & Ameloblastic Fibro-odontome (AFO)

• Previously distinct, now classified with developing odontomes.
• AFD includes dentine formation.
• AFO includes enamel and dentine formation.
• Often soft tissue-only.

Adenomatoid Odontogenic Tumour (AOT)

• Benign, slow-growing, adenoma-like tumour.
• Common in anterior maxilla, often involving unerupted canines.
• Second decade of life.
• Non-infiltrative, expansile, painless cortical expansion.
• Contains mineralized tissue (unlike dentigerous cysts).
• Unilocular, smooth, well-defined, corticated outline.
• Initially radiolucent, developing small internal calcifications.
• Jaw expansion and tooth displacement/non-eruption.
• Predominantly epithelial; occasional palisaded ameloblast-like cells, solid islands of epithelium with duct-like spaces.
• Enamel matrix secretion can mineralize, forming radiodensities; dentinoids.

Calcifying Odontogenic Cyst/Tumour (COC)

• Cystic or solid form.
• Wide age range; any tooth-bearing site in maxilla or mandible; often near unerupted teeth.
• Typically ~4 cm in size.
• Smooth, well-defined, corticated outline on radiographs.
• Initially radiolucent, developing internal calcifications.
• Displacement/resorption of adjacent teeth; potential bony expansion.
• Odontogenic epithelium lining the cyst.
• Diagnostic feature: “ghost cells” (flattened epithelial cells with absent nuclei).
• Lamellar arrangement of ghost cells.
• Solid COCs require wide excision.

Odontome (Odontoma)

• Common benign malformation/most differentiated odontogenic tumor.
• Perfect histodifferentiation (distinct tissue layers).
• Variable morphodifferentiation (shape formation).
• Forms tooth-like structures or disorganised dental tissues.
• Well-mineralised; can expand jaws if large; treatable with simple procedures if small.

Types

• Complex Odontoma: Disorganised masses of enamel, dentine, and pulp. May contain pulpal tissue spaces; radiolucent initially, becoming radiopaque.
• Compound Odontoma: Cluster of small denticles; contains pulp, odontoblasts, dentine, and enamel.

Developing Odontomes

• Previously classified as specific entities (ameloblastic fibrodentinoma, fibro-odontoma).
• Incomplete maturation/mineralisation.