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Oral Surgery · single question

What is the maximum recommended extra-oral (dry) time after avulsion before periodontal ligament cells become non-viable?

  1. 30 minutes
  2. 60 minutes
  3. 90 minutes
  4. 120 minutes
Show answer and explanation

Correct answer: B. 60 minutes

  • A. Significant cell death begins well before this, but the accepted clinical threshold for likely non-viability is longer.
  • B. Correct. PDL cells are considered non-viable after about 60 minutes of extra-oral dry time (regardless of storage medium thereafter, per IADT). Replant ASAP — ideally within 5 minutes; store in milk/HBSS/saliva if delayed.
  • C. Beyond 60 minutes PDL cells are already considered non-viable.
  • D. By 120 minutes the prognosis is poor; cells are non-viable well before this.

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