Peripheral osteoclastic activity causes which condition?

• A. External root resorption
• B. Internal root resorption
• C. Condensing osteitis
• D. Idiopathic osteosclerosis

Answer: (A)

Osteoclasts breaking down mineralized tissue on the outside of a tooth root within the periodontal ligament produces external root resorption. When the resorptive cells act on the external surface, they erode cementum and dentin from the outside, often in response to trauma, orthodontic forces, or chronic inflammation. Internal root resorption, in contrast, comes from activity inside the pulp chamber or canal walls, not on the exterior surface. Condensing osteitis is a sclerosis reaction around the apex due to inflammation, not root surface loss. Idiopathic osteosclerosis is dense bone unrelated to root resorption or inflammatory processes. So peripheral osteoclastic activity causing external root resorption is the correct explanation.