PDL Space Radiographic Appearance — NDEB AFK MCQ
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Correct answer: C — Periodontal ligament space
The periodontal ligament (PDL) space appears radiographically as a thin, uniform, radiolucent (dark) line between the root surface (cementum) and the alveolar bone proper (lamina dura). Its width is approximately 0.15-0.38 mm (average 0.25 mm). Widening of the PDL space can indicate: occlusal trauma, periapical pathology, orthodontic forces, or early periodontal disease. Loss of the PDL space (ankylosis) indicates direct bone-to-root fusion with loss of the radiolucent line.
Reference: White & Pharoah – Oral Radiology: Principles and Interpretation, 8th ed., 2019