Cysts of the maxilla and mandible are common occurrences. Bone cysts occur more frequently in the jawbones than in any other bone because of the presence of epithelium from odontogenic elements, derived from the dental lamina, rests of Malassez, and the tooth germ, and nonodontogenic epithelial remnants of embryonic structures, such as salivary glands and sinonasal epithelium.
A cyst is defined as an epithelial-lined pathologic cavity. The epithelium is surrounded by fibrocollagenous connective tissue. A group of cystic lesions devoid of an epithelial lining is classified as a pseudocyst.
ESSENTIALS OF DIAGNOSIS
Well-defined, radiopaque border.
Predominantly radiolucent, and sometimes expansile lesions.
Usually slow-growing, benign, and asymptomatic.
If long-standing, can present with significant enlargement or secondary infection.
Usually initially discovered on routine dental imaging.
Requires histopathologic examination for diagnosis.
Jaw cysts encompass a group of lesions that are variable in their incidence, etiology, location, clinical behavior, and treatment. Cysts occur in both the mandible and the maxilla. Each type of jaw cyst usually has a specific behavior pattern, ranging from small 5-mm to 6-mm osteolytic defects to massive involvement of the jaw and contiguous structures. Cysts grow by hydraulic pressure and typically contain fluid, gas, or semisolid material. Typically, no fenestration of cortex is noted; however, if present for long enough, some breakthrough can be noted.
Classification of Jaw Cysts
The classification of jaw cysts includes (1) odontogenic cysts, (2) nonodontogenic cysts, and (3) pseudocysts. Odontogenic cysts are further divided into developmental and inflammatory. The ganglion and synovial cysts, which present in the temporomandibular joint (TMJ), have been added to this conventional classification for completeness; it is significant to clinicians managing the pathology of the head and neck region.
The pathogenesis of jaw cysts varies according to the specific cyst type. Inflammatory cysts derive their epithelial lining from the proliferation of odontogenic epithelium within the periodontal ligament; odontogenic developmental cysts result from the proliferation of primordial odontogenic tissues. Figure 25–1 illustrates the development of an odontogenic developmental cyst and an odontogenic inflammatory cyst. Cystic lesions may also result from cortical bone defects or trauma, they may represent reactive lesions, or they may have an unknown pathogenesis. An osmotic pressure gradient produces fluid accumulation within the cyst lumen and generates hydraulic pressure, creating cyst expansion.
(A) Development of the dentigerous cyst around the crown of an unerupted tooth. (B) Development of a radicular cyst around the root apex of a nonvital tooth.
It may be possible to prevent odontogenic jaw cyst formation through the immediate treatment of nonvital teeth and the removal of impacted or unerupted teeth. Strategies should include preventing the progression of jaw cysts to large, destructive ...