Odontoma

Odontoma is the commonest odontogenic tumour, accounting for about 22 percent of all odontogenic tumours and about 65 percent of those in children. It is a hamartomatous malformation composed of enamel, dentine, cementum and pulp tissue in an organised pattern. Compound odontoma has multiple tooth like structures (denticles) and complex odontoma is a disorganised mass of calcified dental tissue.

Peak detection is in the first and second decades, usually associated with a failure of eruption of a permanent tooth. The anterior maxilla (compound type, incisor canine region) and the posterior mandible (complex type, molar region) are the common sites. Causes include local trauma, infection, inheritance (Gardner syndrome and Hermann syndrome), and mutation of genes controlling tooth development.

Growth stops once calcification is complete, so the lesion is self-limiting; it is benign and does not recur after complete removal (recurrence under 1 percent). Large lesions can cause jaw expansion, displacement of teeth and, rarely, cystic change (dentigerous cyst).

• Usually asymptomatic, found on routine radiographs, often during investigation of a failed tooth eruption or retained primary tooth.
• Delayed eruption, displacement or impaction of adjacent teeth, malocclusion.
• Painless swelling or bony expansion in some cases; erupted odontoma (rare) shows a hard, grey or yellow mass in the gingiva.
• Pain, swelling, and fever if infected.
• Gardner syndrome: multiple odontomas with osteomas, colorectal polyps, epidermoid cysts, supernumerary teeth.
• Red flags: multiple lesions at an early age (check for Gardner syndrome and colonic polyps), rapid expansion, pain, or radiolucent component suggesting cystic change.

• Panoramic or periapical radiograph: compound odontoma shows multiple small, tooth like radiopaque structures of varying size and shape within a radiolucent halo; complex odontoma shows an irregular amorphous radiopaque mass with a radiolucent rim; unerupted tooth in the vicinity.
• Cone beam CT: localisation, relationship to teeth, inferior alveolar canal, and nasal floor or sinus, which guides surgery.
• Histology: disorganised or tooth like arrangement of enamel matrix, dentine, cementum and pulp tissue, thin fibrous capsule.
• Screening for Gardner syndrome when multiple or recurrent odontomas or other features: colonoscopy, APC gene testing, family history, and abdominal ultrasound.
• Exclude cementoblastoma, osteoblastoma, ameloblastic fibro odontoma, calcifying odontogenic cyst, adenomatoid odontogenic tumour, cemento osseous dysplasia, and supernumerary teeth.

• Surgical removal under local anaesthesia (lidocaine 2 percent with adrenaline 1:80 000, 1.8 to 3.6 mL) or general anaesthesia for children or large lesions: flap elevation, bone removal with burs, enucleation of the odontoma (sectioning if large), with extraction of retained deciduous tooth, and curettage of the follicle; preserve the associated unerupted tooth where possible.
• Timing: remove early, once diagnosed, before it obstructs eruption; for unerupted permanent teeth, expose and guide eruption by orthodontic traction after removal (spontaneous eruption in about 60 to 70 percent within 12 to 24 months).
• Postoperative: analgesia with paracetamol 1 g every 6 hours (children 15 mg/kg), ibuprofen 400 mg every 8 hours (children 5 to 10 mg/kg) for 3 days; chlorhexidine 0.12 to 0.2 percent mouthwash 10 mL twice daily for 7 days; antibiotics only for infection (amoxicillin 500 mg every 8 hours for 5 days).
• Send all tissue for histology.
• Gardner syndrome: refer for colonoscopy (annual from age 10 to 12 years) and prophylactic colectomy; genetic counselling.
• Complications: damage to adjacent teeth, nerve injury, sinus perforation, fracture, infection.
• Follow up: clinical and radiographic review at 6 and 12 months, then as needed; monitor eruption of displaced teeth.
• Counselling: benign nature, excellent prognosis, no recurrence after removal, and encouraging regular dental review in children.