Primordial cyst versus keratocyst.

The term primordial cyst was introduced in 1945 to identify the odontogenic cyst formed from enamel organ before calcification occurred as part of a classification based on development, structure, and radiographic appearance. The term odontogenic keratocyst was introduced in 1956 to describe cysts of the jaw exhibiting keratinization of their lining. Periodontal, dentigerous, primordial, residual, and gingival cysts may exhibit keratinized linings and can properly be identified as odontogenic keratocysts on the basis of their histologic appearance but may also be identified by their "developmental" designation. There is no justification for considering odontogenic keratocyst as a synonym for primordial cyst.