Benign Odontogenic Tumours Overview

Benign Odontogenic Tumours

• Mixed Odontogenic Tumours:

  • Benign, comprising both epithelial and mesenchymal cells.
  • Lacks hard dental tissues.
  • Commonly found in the 2nd decade, in the premolar/molar region of the mandible or maxilla.
  • Presents as a painless, slow-growing swelling or missing tooth.
  • Impeded eruption of adjacent teeth in children is a common sign.
  • Multilocular and smooth, well-defined, corticated shape on radiographs.
  • Radiolucent with internal radiopaque septa.
  • Displays expansion and displacement of adjacent teeth.
  • Composed of branching strands of odontogenic epithelium embedded in ectomesenchymal stroma.
  • Resembles, but is more developed, than budding tooth germs.
  • Possesses palisaded ameloblast-like cells with reversed polarity (nucleus positioned away from the basement membrane).

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

  • Previously classified separately, now considered developing odontomes.
  • AFD includes dentine formation; AFO includes enamel and dentine.
  • Often exhibit only soft tissue components.

• Adenomatoid Odontogenic Tumour (AOT):

  • Slow-growing, benign tumour resembling an adenoma.
  • Common in the anterior maxilla, often involving unerupted canines, in the 2nd decade.
  • Non-infiltrative and expansile, with painless cortical expansion.
  • Contains mineralized tissue which differentiates from dentigerous cysts.
  • Unilocular, smooth outline, and corticated on radiographs.
  • Initially radiolucent, gradually developing small internal calcifications.
  • Shows expansion and tooth displacement or non-eruption.
  • Predominantly epithelial, with occasional palisaded ameloblast-like cells.
  • Features solid epithelium islands with duct-like spaces, and enamel matrix secretion which often mineralizes.
  • May contain dentinoids.

• Calcifying Odontogenic Cyst/Tumour (COC):

  • Presents in cystic and solid forms.
  • Found throughout the maxilla or mandible, often near unerupted teeth; across a wide age range.
  • Characterized by small size (typically less than 4 cm), and potentially multilocular or unilocular.
  • Smooth, well-defined, and corticated on radiographs, initially radiolucent but eventually developing internal calcifications.
  • May cause displacement/resorption of adjacent teeth and/or expansion of bone.
  • Diagnosed by ghost cells and a characteristic layered arrangement of cells.
  • Solid variants require wider removal margins.

• Odontome (Odontoma):

  • Benign tooth malformation, the most differentiated odontogenic tumour.
  • Demonstrates perfect histodifferentiation (distinct tissue layers) and variable morphodifferentiation (shape formation).
  • Forms tooth-like structures or disorganized dental tissues, and is well-mineralized.
  • Potentially expands the jaws if large, and treated with simple oral surgery if small.
  • Complex Odontome: Disorganised masses of enamel, dentine, and pulp.
  • Compound Odontome: Cluster of small denticles (tooth-like structures).
  • Both types are initially radiolucent, becoming radiopaque over time.

• Developing Odontomes:

  • Previously named 'ameloblastic fibrodentinoma' or 'fibro-odontoma.'
  • Characterized by incomplete maturation or mineralisation.