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Endodontics · single question

What is the MOST useful test to differentiate an acute apical abscess from an acute periodontal abscess?

  1. Palpation test
  2. Periapical radiograph
  3. Electric pulp test (EPT)
  4. Anesthetic test
Show answer and explanation

Correct answer: C. Electric pulp test (EPT)

  • A. Incorrect. Palpation tests the apical region for swelling/tenderness — useful but not the MOST useful differentiating test.
  • B. Incorrect. Periapical radiograph may show a periapical lesion (endodontic) or alveolar bone loss (perio) but cannot always definitively distinguish the two without supplementary testing.
  • C. Correct. The ELECTRIC PULP TEST (EPT) is the MOST useful differentiating test. An acute APICAL ABSCESS is of endodontic origin — the pulp is NECROTIC, so the tooth gives NO RESPONSE to EPT (no electrical stimulus). An acute PERIODONTAL ABSCESS is of periodontal origin — the pulp remains VITAL, so the tooth RESPONDS NORMALLY to EPT. This distinction determines the treatment direction (endodontic vs. periodontal).
  • D. Incorrect. Anesthetic test is used to identify which tooth/nerve is causing pain — not specifically for abscess differentiation.

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