Complex Odontoma

Complex odontoma is a benign hamartoma of the tooth forming tissues in which enamel, dentine, cementum and pulp are laid down as a disorganised, dense mass with no tooth like shapes. It is the less ordered of the two types of odontoma.

It is found in children and young adults, and in contrast with the compound type it is more common in the posterior mandible. Most are found on radiographs because a tooth fails to erupt.

Pathophysiology. A developmental malformation of the odontogenic epithelium and mesenchyme produces mature dental tissues in a haphazard pattern, within a fibrous capsule. Growth stops when the tissues mature.

Associated factors are local trauma and infection, and syndromes with multiple odontomas such as Gardner syndrome. A cyst, most often dentigerous, can form in the capsule.

Most patients have no symptoms. Findings include a retained primary tooth, a missing permanent tooth, delayed eruption, painless cortical expansion and displacement of neighbouring teeth. Infection or discharge is uncommon, and an erupted odontoma can cause gingival inflammation.

Multiple lesions or lesions in several family members indicate a syndrome that needs screening.

• Periapical or panoramic radiograph: a dense radiopaque mass with the density of tooth structure, surrounded by a thin radiolucent rim, often related to the crown of an unerupted tooth.
• Cone beam CT: size, relation to the impacted tooth, inferior alveolar canal and sinus, and planning.
• Histology of the removed specimen: disorganised enamel, dentine and cementum with pulp tissue and a fibrous capsule.
• Biopsy is not needed when the appearance is typical.
• Examination and family history for polyposis and osteomas when lesions are multiple.

Differential diagnosis.

• Compound odontoma
• Ameloblastic fibro odontoma (younger patients, partly radiolucent)
• Osteoma and complex osteoid lesions
• Cementoblastoma (attached to a root)
• Central ossifying fibroma
• Calcifying epithelial odontogenic tumour
• Idiopathic osteosclerosis and condensing osteitis

• Conservative surgical removal of the whole lesion with its capsule, in one piece or after sectioning, with bone preservation. This is curative and recurrence is rare.
• Expose any impacted tooth during the same operation, and use orthodontic traction to bring it into the arch. Earlier removal gives a better chance that the tooth erupts without traction.
• Observation with radiographic review is acceptable for small, asymptomatic lesions that do not affect eruption or adjacent teeth.
• Send the capsule for histology to exclude a cyst or other change.
• Antibiotics only for infection with spread: amoxicillin 500 mg orally three times daily for 5 days (reduce to 500 mg every 12 hours at eGFR 10 to 30), or clindamycin 300 mg four times daily in penicillin allergy. In children use amoxicillin 125 mg three times daily at 1 to 11 months, 250 mg at 1 to 4 years and 500 mg at 5 to 11 years.
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food, with weight based doses in children.

Special groups. Multiple odontomas need colonoscopy and genetic referral to exclude Gardner syndrome, because of the risk of colorectal cancer.

Monitoring. Radiographs at 6 and 12 months for bone fill and for eruption of the preserved tooth, with orthodontic review at 3 to 6 months.

Referral and escalation. Refer to oral and maxillofacial surgery and orthodontics. Refer to gastroenterology and genetics for multiple lesions or a family history of polyposis.