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Ameloblastoma

The ameloblastoma is the most common clinically significant odontogenic tumor.

Its relative frequency equals the combined frequency of all other odontogenic tumors, excluding odontomas.

 Ameloblastomas are tumors of odontogenic epithelial origin.

Etiology:

 They may arise from rests of dental lamina, from a developing enamel organ, from the epithelial lining of an odontogenic cyst, or from the basal cells of the oral mucosa.

They are slow-growing, locally invasive tumors that run a benign course in most cases.

They have  three different clinical- radiographic presentations, which deserve separate consideration because of potentially differing therapeutic considerations and prognosis:

  1. Conventional solid or multicystic (about 75% to 86% of all cases)
  2. Unicystic (about 13% to 21% of all cases)
  3. Peripheral (extraosseous) (about 1% to 4% of all cases)


Conventional Solid or Multicystic Intraosseous Ameloblastoma

Clinical and Radiographic Features

 A painless swelling or expansion of the jaw is the usual clinical presentation If untreated, then the lesion may grow slowly to massive or grotesque proportions.  Pain and paresthesia are uncommon, even with large tumors.

Conventional solid or multicystic intraosseous ameloblastoma is encountered in patients across a wide age range. It is rare in children younger than age 10 and relatively uncommon in the 10- to 19-year-old group.

The tumor shows an approximately equal prevalence in the third to seventh decades of life. There is no significant sex predilection.

Some studies indicate a greater frequency in blacks; others show no racial predilection.

 About 80% to 85% of conventional ameloblastomas occur in the mandible, most often in the molar-ascending ramus area. About 15% to 20% of ameloblastomas occur in the maxilla, usually in the posterior regions.

The tumor is often asymptomatic, and smaller lesions are detected only during a radiographic examination.

Radiographically, ameloblastomas are osteolytic, typically found in the tooth-bearing areas of the jaws, and they may be unicystic or multicystic.The radiographic features  may show honeycomb, multilocular, and/ or unicystic appearance. All were typical solid/multicystic ameloblastoma on biopsy.

 Because ameloblastomas are slow growing, the radiographic margins usually are well defined and sclerotic.

 In cases in which connective tissue desmoplasia occurs in conjunction with tumor proliferation, ill-defined radiographic margins are typically seen. This variety, known as desmoplastic ameloblastoma, also has a predilection for the anterior jaws and radiographically may resemble a fibro-osseous lesion.

The generally slow tumor growth rate may be responsible for the movement of tooth roots. Root resorption occasionally occurs in association with ameloblastoma growth.

A panoramic view shows a unicystic ameloblastoma presenting as a unilocular radiolucent lesion associated with the right mandibular impacted third molar.

A multilocular extensive ameloblastoma is found on the right aspect and ramus of the mandible in relation to an impacted molar tooth.

​Ameloblastoma of the mandible producing marked cortical expansion

A 38-year-old male with right-sided facial swelling. Preoperative orthopantomogram revealed multilocular lucencies (arrows) on the right side.

 Follicular Ameloblastoma

Case 1, multiloculated hypodense image; B- Case 1, expansion of lingual cortical bone; C- Case 2, hypodense unilocular image with apical displacement of the lower left third molar; D- Case 2, important cortical bone expansion.

Treatment

Excision

Curettage; recurrence rate as high as 40% (seen as late as 9 years after surgery)

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