- Radicular cysts are the most common type of cyst, occurring at the apex of a nonvital tooth with necrotic pulp. They appear on radiographs as well-defined, radiolucent lesions with a curved outline located at the apex of a tooth root. - Dentigerous cysts are the second most common type of cyst, occurring around the crown of an unerupted tooth. On radiographs they appear as well-defined, radiolucent lesions with a curved, circular outline that is attached to the cementoenamel junction of an unerupted tooth. - SBCs (simple bone cysts) occur more commonly in the mandibular ra