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Periapical cyst

Dr Abhilash Sandhyala and Dr Frank Gaillard et al.

A periapical cyst (also known as a radicular cyst) is the most frequent cystic lesion related to teeth (see mandibular lesions).

Pathology

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.

Epidemiology

These are typically seen in middle to older age (3^rd to 6^th 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.