A periapical radiolucency is seen at a tooth that has NOT had root canal treatment (the tooth is present and non-vital). The lesion is most consistent with:

Correct answer: A. Apical periodontitis / periapical (radicular) inflammatory lesion

• A. Correct. A periapical radiolucency on a non-vital, untreated tooth reflects pulpal necrosis causing apical periodontitis (periradicular abscess/granuloma/radicular cyst).
• B. A residual cyst persists in the bone AFTER the offending tooth has been extracted — but the tooth is still present here.
• C. The maxillary sinus is a normal radiolucent air space, not a periapical pathologic lesion tied to a non-vital tooth.
• D. A nasopalatine duct cyst is a midline anterior maxillary lesion unrelated to a specific non-vital tooth's apex.