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Endodontics · single question

Which tooth injury is most likely to cause pulpal necrosis?

  1. Extrusion
  2. Subluxation
  3. Intrusion
  4. Concussion
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Correct answer: C. Intrusion

Intrusion luxation carries the highest risk of pulpal necrosis (~96% in mature teeth) because the apical neurovascular supply is severely compressed or severed as the tooth is driven into the socket. This disrupts blood flow to the pulp almost completely. Extrusion and subluxation have lower rates of necrosis.
  • A. INCORRECT. Extrusion displaces the tooth out of the socket partially. The necrosis rate is moderate (~26%) but significantly lower than intrusion.
  • B. INCORRECT. Subluxation involves loosening without displacement. Pulpal necrosis rate is low (~15%).
  • C. CORRECT. Intrusion drives the tooth into the alveolar bone, crushing the apical neurovascular bundle. This has the highest risk of pulpal necrosis of all luxation injuries (~96% in mature teeth).
  • D. INCORRECT. Concussion is the mildest injury — sensitivity to percussion with no mobility or displacement. Necrosis rate is very low (~3%).

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