According to the WHO histological classification of odontogenic tumours, odontomas originate from odontogenic epithelium and odontogenic ectomesenchyme, with or without hard tissue formation. They are generally classified into two types: complex and compound. Odontomas are usually intraosseous and often associated with delayed eruption of teeth. However, they can be extraosseous and are then referred to as either peripheral complex or compound odontoma. Peripheral odontomas are rare entities. We report a case of an 11 year old boy referred to the Department of Oral and Maxillofacial Surgery, Aarhus University Hospital by the boy’s dentist due to fibrous mass in the marginal gingiva in the anterior lower mandible. Removal of the mass revealed a peripheral complex odontoma and at the final 5-month postoperative inspection there was satisfying healing observed, a small, elevated, hyperplastic fibrous marginal gingiva.
Odontomas fall within the category of mixed epithelial and mesenchymal odontogenic tumours. The epithelial part gives rise to enamel and the mesenchymal part produces dentin via odontoblast differentiation. They are hamartomas of aborted tooth formation, the definition of a hamartoma is: a tumorlike dysmorphic proliferations of cells native to the organ in which they arise. They gain a certain size before ceasing their proliferation. They may be expansile but do not invade tissue [
Odontomas are classified into: complex and compound. Complex odontomas form an amorphous mass which is unrecognizable as dental tissues compared to the compound type which forms multiple small tooth-like structures which show three separate dental tissues (enamel, dentin and cementum) [
The patient, an 11-year old boy was referred to the Department of Oral and Maxillofacial Surgery at the University Hospital in Aarhus, Denmark due to a fibrous mass in the labial marginal gingiva of the lower right lateral incisor. The patient was of African ethnicity. He reported that he had been aware of the fibrous mass for at least 2 years and that it had slowly grown in size in that period. He had not noticed any particular bleeding or pain, however it was starting to cause him discomfort during food intake. In regard to his general health and medical history there was nothing specific to report.
Extraoral clinical examination did not reveal any asymmetry. The intraoral examination revealed that the patient was at dental age stage DS4 M1 according to Björk et al. 1964 classification [
The differential diagnosis according to the clinical and radiographic examination was either a peripheral giant cell granuloma or a peripheral ossifying fibroma.
It was decided to perform an excisional biopsy to determine the definitive diagnosis. There was no suspicion of malignancy. Under local anesthesia, the fibrous mass was removed in whole. It had underlying relation to the facial alveolar bone. The area was left to heal by secondary intention. At follow-up 2
weeks later, the patient described a uneventful postoperative period. A small tooth fragment was found peripherally and was removed, otherwise uneventful healing was seen. At 3-months postoperatively a small area of exposed bone (3 × 2 mm) was described and finally at 5-months postoperatively a small, elevated, hyperplastic fibrous marginal gingiva was observed (
Macroscopic examination of the specimen showed soft tissue covered by mucosa measuring at 9.0 × 8.0 × 4.0 mm in size. It had a half-spherical form, which was divided longitudinally and revealed bone like material on the cut surface. The specimen was hard as bone prior to decalcification and moderately indurated after.
Microscopic examination showed at low power view a complex odontoma encapsulated by slightly chronically inflamed dense connective tissue superficially covered by well differentiated slightly parakeratotic squamous epithelium of the oral mucosa (
The histological slides were made after decalcification, where the red dentin and bone/cement matrix (collagen component) were preserved while most of the enamel was dissolved (shown as empty spaces) with a few small rests of enamel which are shown with arrows on the histological slides.
Intraosseous odontomas are among the most common odontogenic tumours together with ameloblastomas [
Author | Age (y)/sex | Type | Location | Clinical findings | Radiologic findings |
---|---|---|---|---|---|
Giunta and Kaplan 1990 [ | 5/F | Compound | Post palatal gingiva | Early rapid growth face, presumed a periodontal abscess | No radiographic appearance |
Giunta and Kaplan 1990 [ | 21/M | Compound | Gingiva post mandible | Firm, asymptomatic mass | Diagnosed radiographically in its mature phase |
Castro et al. 1994 [ | 6/M | Compound | Upper labial gingiva | Dome-shaped, gingival mass. Pink, firm and asymptomatic. Surface ulceration present | No apparent pathology |
Ledesma-Montes et al. 1996 [ | 3/F | Compound | Lingual gingiva mandible | Slow growing, asymptomatic tumour between lower left primary canine and first molar | Nothing remarkable noted |
Ide et al. 2000 [ | 39/M | Compound | Upper labial gingiva | Firm gingival, extraosseous mass | Dense radiopaque mass, no evidence of intraosseous lesion |
Kintarak et al. 2006 [ | 13/F | Compound | Palatal region | Slow growing, asymptomatic mass between maxillary right central incisor and lateral incisor | No obvious pathology |
Bernardes et al. 2008 [ | 12/M | Compound | Upper labial gingiva | Asymptomatic, slightly reddish, firm 4 mm diameter nodule | Not reported |
Ide et al. 2008 [ | 7/F | Peripheral developing odontoma | Ant mandible | A gingival nodule with a dimension of 8 mm | Tiny radiopaque mass on the cervical area of lateral incisor |
Silva et al. 2009 [ | 8 months/M | Peripheral developing odontoma | Palatal region | Slow growing, asymptomatic congenital nodule | Not reported |
Silva et al. 2009 [ | 5 months/M | Peripheral developing odontoma | Palatal region | Asymptomatic, firm nodule | Not reported |
Friedrich et al. 2010 [ | 3/M | Peripheral developing odontoma | Palatal region | Asymptomatic, small, firm protrusion | Small radiopaque, extraosseous deposits |
Hanemann et al. 2013 [ | 15/F | Compound | Upper labial gingiva | Six small tooth-like structures in the ant left gingiva of the maxilla | Irregular tooth structures composed of crown, root and pulp without bone involvement |
Koneru et al. 2014 [ | 15/M | Complex | Labial gingiva ant maxilla | Slow growing, asymptomatic two tiny white nodular masses | No underlying bone resorption and no intra-osseous involvement |
Johannsson et al. 2017 | 11/M | Complex | Labial gingiva ant mandible | Fibrous mass in the labial marginal gingiva | Slight radiopaque, demarcated mass in area of lower right lateral incisor |
features of the calcified dental tissues. This can make it extremely difficult to identify on a radiographic examination, especially the peripheral type. There also seems to be a lack of consensus in regard to histogenesis of extraosseous odontomas. There are also different theories regarding the specific etiological factors causing the development of extraosseous odontomas, including infection, trauma and genetic factors [
The fact that peripheral odontomas are relatively uncommon, as well the fact that the complex type occurs more seldom than the compound type, makes it hard to diagnose clinically. It can appear as in this case, as a fibrous mass in the marginal gingiva where the thought of a peripheral odontoma does not come first to mind as a differential diagnosis. The fact that they can also arise at different stages of calcification can make it hard to diagnose them on a radiographic examination, as it was in this case report. It was very radiolucent and even hard to detect at a closer look. In light of the aforementioned information, the need for biopsy is clear, since you can only gain so much information from the clinical and radiographical aspects.
None.
Author 1, Gunnar Ingi Jóhannsson declares that he has no conflict of interest. Author 2, Steen Bærentzen declares that he has no conflict of interest. Author 3, Johan Blomlöf declares that he has no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
In relation to publication of this case report and any additional related information, informed consent was given by the patient’s parents.
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Jóhannsson, G.I., Bærentzen, S. and Blomlöf, J. (2017) Peripheral Complex Odontoma in the Gingiva: A Case Report of an 11 Year Old Boy and Review of Literature. Open Journal of Stomatology, 7, 419-427. https://doi.org/10.4236/ojst.2017.79036