The Periapical Cyst is a type of cyst that forms at the root of a tooth, caused by an infection in the pulp. There are several synonyms for Periapical Cysts: Radicular Cyst, Apical Periodontal Cyst, Dental Cyst, and Apical Root Cyst. All these terms refer to cysts that develop at the end of the root of a tooth. These cysts can cause severe toothache and swelling of the surrounding tissue, as well as lead to tooth loss if left untreated. Treatment for Periapical Cysts varies from antibiotics, root canal therapy, and sometimes surgical removal of the infected tissue may be warranted.