Radiological features of mandibular primordial cysts. (Keratocysts).

Primordial cysts (keratocysts) have been shown to have a greater tendency to recurrence than other jaw cysts. Some radiological features may assist in establishing the diagnosis. Thirteen mandibular primordial cysts have been studied radiologically in detail. Characteristic features are extension along the medulla with minimal expansion except in young children. Margins are generally sharply demaracated and either smooth or scalloped. Cortical resorption occurs before expansion. The cysts may displace adjacent teeth, particularly when unerupted, but generally do not produce root resorption. They may displace the neurovascular bundle. Antero-posterior dimensions in this series ranged from 28 to 77 mm, with a mean of 50 mm.