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Periapical cyst

Periapical cysts (also known as radicular cysts) are the most frequent cystic lesion related to teeth (see mandibular lesions).


It results from infection of the tooth, which spreads to the apex and into the adjacent bone. This leads to apical periodontitis, granuloma formation and eventual cyst formation. These cysts are therefore centered on the apex of the tooth, and tend to be small, most less than 1 cm. There is also unsurprisingly usually overt evidence of caries.


These are typically seen in middle to older age (3rd to 6th decades 2).

Radiographic features

Plain film, OPG and CT

At radiography, most radicular cysts appear as round or pear-shaped, unilocular, lucent lesions in the periapical region 3.

They are usually less than 1 cm in diameter and are bordered by a thin rim of cortical bone. The associated tooth usually has a deep restoration or large carious lesion.

Differential diagnosis

Related articles

Lucent lesions of the jaw

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