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Endodontics · single question

The BEST diagnostic test to differentiate between an acute periapical abscess and an acute periodontal abscess is:

  1. Periapical radiograph
  2. Percussion test
  3. Palpation test
  4. Electric pulp test (EPT) — to determine tooth vitality
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Correct answer: D. Electric pulp test (EPT) — to determine tooth vitality

  • A. Periapical radiographs show bone loss patterns (lateral bone loss = perio; periapical radiolucency = PA abscess) but cannot definitively determine pulp vitality.
  • B. Percussion tests indicate apical inflammation (present in both) but do not determine vitality.
  • C. Palpation tests can locate swelling and tenderness but cannot determine pulp vitality — the key differentiator.
  • D. Correct. The KEY clinical distinction between a periapical abscess (pulpal origin) and a periodontal abscess is TOOTH VITALITY. Periapical abscesses always occur in NON-VITAL (necrotic) teeth. Periodontal abscesses can occur with vital teeth. The EPT (electric pulp test), or cold/heat test, determines pulp vitality — this is the single best differentiating test.

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