Consider these two statements. (1) There is usually no lesion apparent radiographically in acute apical periodontitis. (2) Histologically, bone destruction has nevertheless been demonstrated. Which is true?

Correct answer: A. Both statements are true

• A. CORRECT. Both are true, and together they explain a classic clinical trap. Acute apical periodontitis is a symptomatic inflammatory response in the periodontal ligament, so the tooth is exquisitely tender to percussion and biting — yet the radiograph often looks normal or shows only a subtle widening of the PDL space. Radiographic lucency requires roughly 30–50% demineralisation of the cortical plate before it becomes visible, so histological bone resorption is well underway before anything shows on film.
• B. Both are in fact true — this is a documented discrepancy between histology and radiography.
• C. The second statement is also true; histological bone destruction has been demonstrated in these lesions.
• D. The first statement is true as well — a normal-looking radiograph is typical in acute apical periodontitis.

Note: Never rule out apical pathology on a clean radiograph. Percussion tenderness with a normal film is the classic presentation of acute apical periodontitis.