Mandible / maxilla
Benign tumors / tumor-like conditions
Odontoma

Author: Anthony Martinez, M.D.
Editor: Kelly Magliocca, D.D.S., M.P.H.
Deputy Editor Review: Debra Zynger, M.D.

Revised: 9 October 2018, last major update March 2018

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Odontoma AND (free full text[sb] AND Humans[Mesh])

Cite this page: Martinez, A. Odontoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mandiblemaxillaodontoma.html. Accessed December 16th, 2018.
Definition / general
  • Mixed epithelial and mesenchymal tumor-like malformation (hamartoma) composed of dental hard and soft tissues
Essential features
  • Subdivided into compound odontoma and complex odontoma
  • The most common odontogenic tumor
  • Can obstruct the path of erupting teeth
  • Most recent WHO Classification of Head and Neck Tumours regards majority of ameloblastic fibro-odontomas as developing odontomas rather than a distinct tumor (IARC: WHO Classification of Head and Neck Tumours, 4th Edition, 2017)
Terminology
  • Compound odontoma
  • Complex odontoma
  • Ameloblastic fibro-odontoma
  • Peripheral odontoma
ICD coding
ICD-O Coding
Epidemiology
  • Most common odontogenic tumor
  • Usually diagnosed during the first two decades of life
  • No sex predilection
Sites
  • Can occur in any tooth bearing area
  • Compound odontoma usually occurs in anterior maxilla
  • Complex odontoma usually occurs in posterior mandible
Pathophysiology
  • Unknown; trauma, local infection, inheritance have been proposed
Etiology
  • Unknown
Clinical features
  • Many asymptomatic; discovered upon exploring potential causes of
    • Asymmetric tooth eruption
    • Malposition of erupted teeth
    • Occasional devitalization of adjacent teeth
  • Can become symptomatic due to local infection (sinusitis, infected adjacent tooth, exposure of odontoma to oral environment, etc) and can present with swelling and pain
  • Size: ranges from several millimeters to 6 cm, most between 1 - 2 cm
  • Syndrome associations:
    • Gardner syndrome (familial colorectal polyposis): multiple odontoma or supernumerary teeth
    • Otodental syndrome
  • Peripheral odontoma may present as a firm submucosal nodule, most commonly in the maxilla
Diagnosis
  • Dependent on clinical, radiologic and pathologic correlation
Radiology description
  • Frequently associated with an unerupted tooth
  • Usually detected on routine radiographs
    • Most commonly located between roots of erupted teeth or impeding the eruption of tooth
  • Well marginated from surrounding bone
    • May have a thin radiolucent region surrounding opaque mass
    • Radiopaque matrix same density as components of adjacent teeth
    • Early stage odontoma may have little calcified matrix, expanding the radiographic differential diagnosis
  • Can occur as a component of combined odontogenic tumor, most commonly Calcifying cystic odontogenic tumor (CCOT)
  • Multiple odontomas may occur as a component of:
    • Gardner syndrome (familial colorectal polyposis)
    • Otodental syndrome
  • Multiple supernumerary teeth (similar radiographic appearance) can occur as a component of cleidocranial dysostosis or arise in non syndromic setting
Radiology images

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Lesion in left side of the mandible

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Compound odontoma and unerupted 32

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Well defined multiple radiopacities

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Radio opaque lesion surrounded by radiolucent zone

Prognostic factors
  • Recurrence uncommon for isolated sporadic odontoma
  • Remaining teeth in region of odontoma may be affected by the presence of odontoma and require treatment
Case reports
Treatment
  • Peripheral odontomas usually treated by excision
  • Central (intraosseous) complex and compound odontomas usually treated by enucleation and curettage
  • Remaining teeth in region of odontoma may be affected, requiring treatment
Clinical images

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Peripheral odontoma

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Surgical site showing denticles

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Mass in upper left maxillary region​​

Gross images

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Enucleated nine denticles

Microscopic (histologic) description
  • General:
    • Can have scant or occasional ghost cell formation, can cause confusion with COC (CCOT / Gorlin cyst) Calcifying cystic odontogenic tumor (CCOT)
      • Odontoma can also occur as a component of COC (about 20% of COC associated with odontoma)
    • Odontoma is composed of dental hard tissues; dentin and enamel
      • Bone is not a dental hard tissue

  • Compound:
    • Histologically similar to the layering of normal tooth in the relation of dentin, enamel matrix and pulp

  • Complex:
    • More disorganized or haphazard arrangement of pulpal tissues, enamel or dentin
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Kelly Magliocca, D.D.S., M.P.H.

Complex odontoma



Compound odontoma

Differential diagnosis
  • Complex:
    • Malformed tooth developing in area of prior trauma
      • Could be histologically identical to complex odontoma
    • Osteoma
      • Benign neoplasm composed of mature lamellar bone (compact, trabecular or both)
      • Can also affect craniofacial bones
      • Should not have odontogenic epithelium
    • Ameloblastic fibro-odontoma (AFO)
      • Has biphasic (mesenchymal and odontogenic epithelium) "soft tissue" component that is identical to ameloblastic fibroma
      • Also contains a calcifying component composed of enamel and dentin structures
      • Most recent WHO Classification of Head and Neck Tumours regards most cases of AFO as developing odontomas rather than a distinct tumor (IARC: WHO Classification of Head and Neck Tumours, 4th Edition, 2017)

  • Compound:
    • Supernumerary teeth
      • Complete well formed teeth
      • Usually in males
      • Can rarely be associated with syndromes such as cleidocranial dysostosis

  • General:
    • Calcifying cystic odontogenic tumor (CCOT)
      • Benign cystic tumor of odontogenic origin, current terminology favors use of calcifying odontogenic cyst rather than CCOT (IARC: WHO Classification of Head and Neck Tumours, 4th Edition, 2017)
      • Can have ameloblastic epithelium: columnar or cuboidal basal cells with lumen lined by tissue resembling stellate reticulum
      • Will have ghost cells or anucleate epithelial cells
      • Can also have dentinoid material admixed with odontogenic epithelial rests
      • Separate discrete focus of odontoma may be present in approximately 20% of cases
Additional references
Board review question #1
    A 15 year old boy is found to have multiple odontomas of the left mandibular body. Upon reviewing his history with the family, he is noted to have had other bone tumors in the past along with multiple epidermal inclusion cysts and GI polyps. What syndrome is he likely to have?

  1. Cowden syndrome
  2. Gardner syndrome
  3. Gorlin syndrome
  4. Peutz Jeghers syndrome
Board review answer #1
B. Gardner syndrome, a variant of familial adenomatous polyposis (FAP), is an autosomal dominant disease characterized by GI polyps, multiple osteomas, skin and soft tissue tumors such as epidermal inclusion cysts and desmoid tumors.

Gorlin syndrome, also known as nevoid basal cell carcinoma syndrome, is associated with basal cell carcinomas, odontogenic keratocysts and fibromas (ovarian and heart). It is caused by PTCH1 mutations.

Peutz-Jeghers syndrome is characterized by the development of noncancerous growths called hamartomatous polyps in the GI and an increased risk of developing certain types of cancer. It is autosomal dominant and caused by STK11 mutations.

Cowden syndrome is an autosomal dominant multiple hamartoma syndrome with PTEN mutations. There is an increased risk of certain forms of cancer, including breast, thyroid, endometrial and kidney cancers.