Compound Odontoma

Compound odontoma is a benign hamartoma of the tooth forming tissues made up of many small, tooth like structures (denticles), each with enamel, dentine, cementum and pulp. It is the more common of the two types of odontoma, with the complex type being less ordered.

It is the commonest odontogenic tumour like lesion. It is found in children and young adults, mostly in the anterior maxilla, and often delays tooth eruption.

Pathophysiology. The lesion is a developmental malformation, not a true neoplasm. A local disturbance in the dental lamina or odontogenic epithelium causes excessive formation of tooth tissue in an organised pattern.

Associations include trauma and infection, and syndromes such as Gardner syndrome. Growth stops once the lesion matures.

Usually asymptomatic, and discovered on a radiograph taken for a retained primary tooth or a missing permanent tooth. Delayed or failed eruption of a permanent tooth, expansion of the cortex or a displaced tooth may be seen. Pain and infection are uncommon.

Erupted denticles may be extruded in the mouth, causing local inflammation. Multiple or recurrent lesions suggest a syndrome, with screening for colonic polyposis and osteomas.

• Periapical or panoramic radiograph: a cluster of multiple small tooth like radiopacities of varying size within a thin radiolucent rim, usually in the anterior maxilla, often with an unerupted tooth.
• Cone beam CT: the number and position of denticles, relation to the impacted tooth, nasal floor and roots, and planning.
• Histology of the specimen: enamel, dentine, cementum and pulp tissue in a recognisable tooth pattern, with a fibrous capsule.
• Biopsy is not needed when the appearance is typical.
• Family history and examination for polyposis when lesions are multiple.

Differential diagnosis.

• Complex odontoma
• Supernumerary teeth and mesiodens
• Ameloblastic fibro odontoma
• Calcifying odontogenic cyst with odontoma
• Cementoblastoma and osteoma
• Calcifying epithelial odontogenic tumour
• Retained root fragments or foreign bodies

• Conservative surgical removal of the entire lesion with its capsule, with the denticles taken out in one piece or several pieces. This is curative, and recurrence is rare.
• Surgical exposure of any impacted tooth after removal, with orthodontic traction to bring the tooth into the arch. The earlier the odontoma is removed, the better the chance of spontaneous eruption.
• Asymptomatic lesions that do not affect teeth can be observed with radiographic review.
• Pathological assessment of the capsule to exclude a cyst or ameloblastic change.
• Antibiotics only for infection: 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 weight based dosing, 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 15 mg/kg every 4 to 6 hours (maximum 75 mg/kg daily) and ibuprofen 5 to 10 mg/kg every 6 to 8 hours for children, or adult doses of 1 g and 400 mg respectively.

Special groups. Children need paediatric anaesthesia or sedation planning, with coordinated orthodontic care. Multiple lesions need screening for Gardner syndrome with colonoscopy and genetic referral.

Monitoring. Radiographs at 6 and 12 months for bone healing and for eruption of the impacted tooth, with review of orthodontic traction 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.