DEFINITION/OVERVIEW

Odontoma: oral mass that arises from odontogenic epithelial and mesenchymal origin
- Ameloblastic fibro-odontoma (AFO) (formerly ameloblastic odontoma): radiolucent mass with osteolysis and varying amounts of intralesional mineralization
- Complex odontoma: radiodense mass with fully differentiated dental components (more organized than AFO), but unorganized at the cellular level with no toothlike structures
- Compound odontoma: mass with fully differentiated dental components resulting in the presence of denticles (toothlike structures; see “Clinical Features” section)
Hamartoma: proliferation of normal cellular components with an abnormal organization—not a true neoplasm (applicable to complex and compound odontoma types)
- A definition to help delineate the three types of odontoma, not a type in itself

ETIOLOGY/PATHOPHYSIOLOGY

SIGNALMENT/HISTORY

Typically found in young animals
Oral swelling or mass (Fig. 43-1)
Delayed deciduous tooth exfoliation or delayed or abnormal tooth eruption at site

Figure 43-1 Expansile mass on right mandible of dog with displacement of permanent teeth.

AFO
- Most lesions are radiolucent with single or multiple (multilocular) expansile lesions of irregular configurations of dental components
- Some lesions are associated with impacted teeth
- Neoplastic mechanism: may recur (WHO—benign neoplasm)
Complex
- Disorganized tissues within a thin, fibrous capsule
- Radiographically, often a radial structure of hard tissue particles inside a radiolucent zone, embedded in the maxilla or mandible
- Erupted teeth in that area may allow for communication between the odontoma and oral cavity, with a potential for bacterial contamination and infection
Compound
- The presence of denticles is pathognomonic (Fig. 43-2)
  - Small, rudimentary teeth with crown formed, but the roots are often misshapen (dilacerated) (Fig. 43-3)
  - Denticles often associated with radiolucency
  - May be embedded or have some extent of eruption