OPG (Orthopantomogram) showing PERIAPICAL RADICULAR CYST at the apex of cairous left lower third molar .
An odontogenic cyst of inflammatory origin that is preceded by a chronic periapical granuloma.
It is a liquid-filled cavity lined with epithelium.
Radiologic features.
1)Rounded,well circumscribed radiolucency at the apex of a nonvital tooth.
2)Often with a distinct thin line of cortication.
Differential diagnosis.
1)Periapical granuloma.
2)Traumatic bone cyst.
3)Cementoma (Periapical cemento osseous dysplasia cyst).