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Orthodontics · single question

Where is the center of resistance located?

Maxillary incisor with significant alveolar bone loss (radiograph).

  1. Apical third of the root
  2. Middle of the root (in healthy bone)
  3. At the crown
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Correct answer: A. Apical third of the root

Alveolar bone loss moves the center of resistance apically (toward the apical third).
  • A. Correct. The center of resistance normally lies near the cervical/middle-third junction; with significant bone loss it migrates APICALLY toward the apical third.
  • B. That approximates the normal position, but the question specifies heavy bone loss, which shifts it apically.
  • C. The center of resistance is within the root, not the crown.

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