Periapical cyst

Overview
The periapical cyst, otherwise known as radicular cyst, is the most common odontogenic cyst. It is caused by pulpal inflammation or pulp death, secondary to trauma or dental caries. The cyst lining is derived from the cell rests of Malassez. Usually, the periapical cyst is asymptomatic, but a secondary inflammation can cause pain. On radiographs, it appears a radiolucency (dark area) around the apex of a tooth's root.