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The well-demarcated non-expansile, unilocular radiolucency with scalloped border in the mandible of a young person should make one think traumatic bone cavity (TBC) and this was the diagnosis. Also, note the demarcation of the radiolucency, it is corticated or clearly defined in some areas. This would be more consistent with TBC. However, the very posterior presence and extension into the ramus of the mandible is not typical of TBC.
The traumatic bone cyst is best called a traumatic bone cavity since this condition does not represent a true cyst. Traumatic bone cavity (TBC) is not unique to the jawbones; it is also described in the long bones and is known as a simple solitary bone cyst occurring mostly in the humerus or femur, close to the epiphyseal plate. The long bone simple cyst is similar to the jaw traumatic bone cavity radiographically and occurs in younger age range. Trauma has been suggested as the etiology along with other non-substantiated theories such as cystic degeneration of a preexisting tumor or of the fatty marrow in the area.
Some reports suggest that it is more common in males while others report equal distribution between males and females. The long bone counterpart is more common in males by a ratio of 2.5:1. Most reports agree that the average age of occurrence is below 20 years of age. These lesions can occur, but are uncommon, over the age of 30. Kaugars reported a higher number of TBC cases in African-American females compared to the literature. The latter patients were over the age of 30. This may suggest an association with florid cemento-osseous dysplasia. The mandible is the most commonly affected area, where over 95% of cases occur, especially in the posterior premolar-molar area. TBCs are also known to cross the midline anteriorly. In one study, 27% of cases were anterior to the canine and some crossed the midline. They are usually unilocular and radiolucent, typically above the alveolar canal, and in many cases have a scalloped superior border squeezing between the roots of teeth. The latter are vital and are frequently found hanging within the empty cavity. About 25% of the lesions occur in the anterior mandible apical to the canine tooth and are usually round and unilocular; they can therefore be mistaken for periapical lesions, leading to an unnecessary endondontic treatment. Therefore, it is important to test the vitality of the teeth and carefully examine the radiographs for changes consistent with a periapical granuloma or cyst. Though expansion is not characteristic of TBC, it is described in about 26% of cases. TBCs are otherwise asymptomatic. The margins of these lesions range from very well defined to corticated to punched-out radiolucency. Pathologic fractures associated with traumatic bone cavity have been described in the jaws, but are rare. They are, however, more common in association with TBCs of the long bones.
Clinically, surgeons report an empty cavity at entrance in about two thirds of cases and cavities filled with straw-colored fluid in about one third of cases. Blood clots are also present occasionally. The bone cavity is scraped to generate bleeding, which is considered the treatment of choice for this condition. Other methods of treatment have been tried, such as packing the curetted cavity with autogenous blood, autogenous bone and hydroxyapetite. Various other reports demonstrate healing of TBC after injection of autogenous blood, after aspiration and after endodontic treatment. These lesions may spontaneously heal, but rarely. Biopsy material consists of fragments of viable bone and loose connective tissue. Osteoclast-like giant cells have also been described in a few cases. Exploration surgery usually leads to healing. Recurrence is rare.