What is the clinical hallmark of a chronic periradicular (apical) abscess?

Correct answer: D. Drainage through a sinus tract

• A. Lesion size is a radiographic observation, not a clinical hallmark, and a large lucency accompanies granulomas and cysts too.
• B. Granulation tissue is a HISTOLOGICAL finding requiring biopsy — it cannot be appreciated clinically.
• C. Cyst formation is also a histological diagnosis and cannot be distinguished from a granuloma on a radiograph.
• D. CORRECT. The defining CLINICAL feature is a SINUS TRACT — the parulis or gum boil. Continuous low-grade drainage vents the pressure, which is precisely why these lesions are asymptomatic. Trace the tract with a gutta-percha point and take a radiograph to identify the offending tooth, because the stoma may be some distance from it.

Note: Once the source tooth has been treated endodontically, the sinus tract needs no separate treatment — it resolves on its own within a couple of weeks.