Internal root resorption occurs within which anatomical space?

• A. Root canal system
• B. Pulp chamber only
• C. Periodontal ligament
• D. Alveolar bone

Answer: (A)

Internal root resorption develops from within the tooth, specifically inside the root canal system—the space that includes the pulp chamber and the root canals. The destructive cells (odontoclasts) act on dentin from the inside, so the resorption stays inside the tooth as it progresses. Structures outside the tooth, like the periodontal ligament and alveolar bone, are involved in external resorption, not this internal process. So the root canal system is the correct anatomical space where internal root resorption occurs.