Odontoma

§ overviewOverview

A benign mixed odontogenic tumour (currently considered a hamartoma) composed of enamel, dentin, cementum and pulp tissue in variable degrees of organisation.

§ icdICD Classification

ICD-10 D16.4/D16.5

§ etiologyEtiology

• 01Local trauma or infection during odontogenesis
• 02Genetic predisposition (Gardner syndrome — multiple odontomas)
• 03Familial cases reported

§ riskRisk Factors

• 01Family history (Gardner)
• 02Trauma during tooth development

§ geneticsGenetics & Molecular Biology

• 01Sporadic — no consistent mutation
• 02Gardner syndrome: APC gene (5q22) mutation → osteomas, colonic polyposis, epidermoid cysts, supernumerary teeth, odontomas

§ epidemiologyEpidemiology

22% of all odontogenic tumours (most common). Peak age: 2nd decade. No sex predilection. Compound — anterior maxilla; complex — posterior mandible.

§ pathogenesisPathogenesis

Abnormal proliferation of tooth germ elements after the stage of morphodifferentiation → deposition of enamel, dentin, cementum in tooth-like (compound) or disorganised (complex) form. Growth ceases once hard tissues mature.

§ clinicalClinical Features

• 01Usually asymptomatic — detected on OPG for failure of eruption
• 02Small painless bony swelling
• 03Retained deciduous teeth / unerupted permanent teeth
• 04Rare eruption ('erupted odontoma') with local infection

§ signsSigns & Symptoms

• 01Delayed / failed eruption of a permanent tooth
• 02Malposition of adjacent teeth
• 03Occasional expansion of cortical plates

§ differentialDifferential Diagnosis

• 01Supernumerary tooth
• 02Ameloblastic fibro-odontoma
• 03Calcifying epithelial odontogenic tumour (CEOT)
• 04Calcifying odontogenic cyst
• 05Osteoma

§ criteriaDiagnostic Criteria

• 01Well-defined radiopacity with radiolucent halo
• 02Density > bone (equivalent to tooth structure)
• 03Histology: mature dental hard tissues in organised (compound) or disorganised (complex) pattern

§ histopathHistopathology

• 01Compound: multiple small tooth-like structures (denticles) with enamel matrix, dentin, cementum and pulp
• 02Complex: haphazard mass of enamel matrix, dentin, cementum and pulp with no resemblance to a tooth
• 03Peripheral fibrous capsule (dental follicle equivalent)

§ radiographicRadiographic Features

• 01Compound: cluster of tooth-like radiopacities (denticles) surrounded by narrow radiolucent halo
• 02Complex: irregular radiopaque mass with radiolucent halo, density greater than bone
• 03Associated unerupted tooth is common

§ opgOPG Findings

• 01Screening view; check for multiplicity → Gardner

§ cbctCBCT Findings

• 01Assess relation to unerupted tooth, IAN canal, nasal cavity for surgical planning

§ ctCT Findings

• 01Rarely required

§ mriMRI Findings

• 01Not indicated

§ investigationsInvestigations

• 01Clinical + radiographic diagnosis usually sufficient
• 02CBCT for planning
• 03Histology after excision
• 04Colonoscopy + APC gene testing if multiple odontomas

§ labsLaboratory Findings

• 01Non-specific

§ ihcIHC / Special Stains

• 01Amelogenin, enamelin positive in enamel matrix; DSP/DPP in dentin

§ whoWHO Classification

WHO 2022: Benign odontogenic tumour of mixed epithelial and mesenchymal origin — Odontoma (compound, complex).

§ classificationClassification

• 01Compound odontoma — multiple denticles, anterior maxilla
• 02Complex odontoma — disorganised mass, posterior mandible
• 03Dilated odontome (variant)
• 04Erupted odontoma (rare)

§ planTreatment Planning

• 01Assess associated impacted tooth for orthodontic salvage vs sacrifice
• 02Small odontoma → surgical enucleation; larger requires bone removal
• 03Screen for Gardner if multiple

§ treatmentTreatment

• 01Surgical enucleation with removal of surrounding fibrous capsule
• 02Orthodontic traction of associated unerupted tooth after odontoma removal
• 03Multiple odontomas → investigate for Gardner syndrome

§ medicalMedical Management

• 01Nil specific

§ surgicalSurgical Management

• 01Conservative surgical excision, sparing developing teeth
• 02Piezosurgery useful in young patients

§ reconstructionReconstruction Options

• 01Small defects heal spontaneously; occasional bone graft for large complex odontoma cavities

§ complicationsComplications

• 01Failure of eruption of associated tooth
• 02Infection of an erupted odontoma
• 03Recurrence extremely rare

§ recurrenceRecurrence Rate

< 1% after complete excision.

§ followupFollow-up Protocol

• 01Post-op OPG at 6 and 12 months
• 02Monitor eruption of associated tooth

§ prognosisPrognosis

Excellent.

§ preventionPrevention

• 01None specifically; family screening in Gardner

§ examKey Examination Points

• 01Most common odontogenic tumour
• 02Compound = anterior maxilla, complex = posterior mandible
• 03Radiopacity denser than bone with thin radiolucent halo

§ revisionQuick Revision Summary

• 01Hamartoma
• 02Most common odontogenic tumour
• 03Compound (anterior maxilla) vs complex (posterior mandible)
• 04Radiopacity + halo
• 05Gardner if multiple

§ vivaBDS Viva Questions

• 01Classify odontomas.
• 02Why is odontoma considered a hamartoma?
• 03Radiographic differential of a mixed radiolucent-radiopaque lesion?
• 04Components of Gardner syndrome.
• 05Which gene is mutated in Gardner syndrome?
• 06Difference between compound and complex odontoma.
• 07Management of an odontoma with impacted permanent tooth?
• 08What is dens invaginatus vs dilated odontome?
• 09Recurrence rate of odontoma?
• 10Histological components of odontoma?

§ bdsBDS Professional Examination

• 01Long essay: Odontogenic tumours — classification and management with focus on odontoma.
• 02Short note: Gardner syndrome.
• 03Short note: Compound vs complex odontoma.

§ fcpsFCPS Residency Questions

• 01Discuss WHO 2022 classification of odontogenic tumours and current concepts on the hamartomatous nature of odontoma.

§ pearlsClinical Pearls

• 01Any impacted tooth in an unusual position — look for an overlying odontoma.
• 02Multiple odontomas + colonic polyps = Gardner — refer for colonoscopy.

§ mnemonicsMnemonics

• 01Compound = Cluster (of denticles), Complex = Chaos

§ readingSuggested Reading

• 01Barnes L et al. WHO Classification of Head & Neck Tumours (2022)
• 02Neville BW. Oral and Maxillofacial Pathology, 4e — mixed odontogenic tumours

§ differentialDifferential Comparison

§ mcqsMCQs — Assessment (20)

§ relatedRelated Diseases

References

1. WHO Classification of Head and Neck Tumours, 5e (2022)
2. Neville BW. Oral and Maxillofacial Pathology, 4e
3. Shafer WG. Textbook of Oral Pathology, 9e
4. Peterson LJ. Contemporary Oral & Maxillofacial Surgery, 7e