Odontoma

Odontomas are hamartomas of odontogenic epithelium and ectomesenchyme, separated into compound and complex types. Both considered as a developmental anomaly, compound odontomas show diminutive tooth-like structures (Figures 1A and 2A), while complex odontomas show a haphazard aggregate of enamel and dentin (Figures 1B and 2B). Odontomas are considered to be one of the most common odontogenic tumors, with most presenting in the first 2 decades of life without sex predilection. Compound odontomas are more common in the anterior maxilla, while complex odontomas are more common in the posterior mandible (Figure 1B). The lesions are usually asymptomatic, detected on routine dental imaging studies, with a few cases reported in Rubinstein-Taybi syndrome. Radiographic features are considered diagnostic, with tooth-shaped structures surrounded by a radiolucent zone in compound odontomas versus a radiodense mass with a radiolucent zone seen in complex odontoma. Simple excision is curative without risk of recurrence.

Figure 1.

A, Compound odontoma (white arrow) showing multiple diminutive tooth-like structures in the anterior mandible. B, Complex odontoma (white arrow), presenting as a radiopaque mass covering an unerupted tooth in the posterior mandible.

Figure 2.

A, Histology of a compound odontoma showing multiple diminutive teeth with well-developed and orderly relationships between the dentin and enamel material. B, Haphazard blending of odontogenic precursors, including dentin-like material, in this complex odontoma.

By gross examination, compound odontoma shows tooth-shaped hard tissues, while complex odontoma shows a disorganized mass of white-yellow hard tissues; both types are associated with fibrous connective tissue.

Compound odontomas have a histologic appearance similar to a normal tooth with mature tubular dentin, enamel matrix, cementum, and pulp tissue (Figure 2A), while a complex odontoma shows a haphazard arrangement of tubular dentin, enamel matrix, cementum, and sometimes epithelial ghost cells (Figure 2B). It is possible to see other odontogenic cysts or tumors with odontomas. The differential includes supernumerary teeth (hyperdontia), root tip due to incomplete tooth extraction, and normal teeth (impacted).