What is internal root resorption?

• A. Inflammatory mediators induce osteoclastic transformation of nondifferentiated connective tissue cells within a root canal system
• B. External root resorption
• C. Condensing osteitis
• D. Idiopathic osteosclerosis

Answer: (A)

Internal root resorption happens when inflammatory mediators from the pulpal tissue cause undifferentiated connective tissue cells inside the root canal to transform into osteoclast-like cells. These clastic cells then resorb dentin from within the canal walls, so the resorption starts inside the root rather than from the outside. This internal process is distinct from external root resorption, which begins on the outer surface of the root, and from conditions like condensing osteitis or idiopathic osteosclerosis, which involve bone changes outside the root structure and are not driven by pulp-originating inflammatory resorption. Clinically, internal resorption is usually addressed with root canal therapy to remove the resorptive tissue and halt the process.