
The residual cyst is a type of inflammatory odontogenic cystic lesion, caused by an inflammatory periapical cyst that persists retained within the bone after extraction of the affected tooth involved, or arises after incomplete removal of an original cyst, motivating the persistence of a radicular cyst. Also known as asymptomatic inflammatory odontgenic cyst, these cysts may rise from inflammatory fibrous and granulation tissue at the apex/periapical region of a tooth not curetted at the time of dental extraction. In this case report, a 40 year old female patient presented with a painless swelling of approximately 2x2 cm in size, on the mandibular left back region since one month. Clinical signs and symptoms suggested of residual cyst. Presentation, diagnosis and management of the cyst is discussed.