What type of cyst is identified with a radiograph showing a radiolucency behind the permanent M2?

The scenario described in the question indicates the presence of a radiolucency located behind the permanent second molar (M2). This finding is characteristic of a primordial cyst.

Primordial cysts typically arise in the area where a tooth would normally develop but fails to form usually due to developmental disturbances. Their location can often be found in the posterior mandible, which aligns with the description of radiolucency behind the permanent M2. These cysts are not associated with the roots of teeth and do not arise from the dental pulp, which differentiates them from some other types of cysts.

In contrast, an odontogenic keratocyst typically appears as a well-defined radiolucency but often has different characteristics and symptoms, as it can be associated with syndromes such as nevoid basal cell carcinoma syndrome. Radicular cysts and periapical cysts, on the other hand, are associated with the roots of nonvital teeth and are manifestations of chronic inflammation resulting from pulpal necrosis, often located at the apex of a tooth. They would not typically present solely as a radiolucency behind a molar without being connected to a nonvital tooth.

Therefore, given the location of the radioluc