What is the KEY feature that distinguishes condensing osteitis from idiopathic osteosclerosis?

Correct answer: C. Condensing osteitis is associated with a non-vital or inflamed pulp; idiopathic osteosclerosis occurs at teeth with normal pulps

• A. Radiodensity is similar in both and cannot reliably separate them.
• B. Neither causes root resorption.
• C. CORRECT. Both appear as well-defined radiopacities in the posterior mandible. The distinction is the PULP STATUS. CONDENSING OSTEITIS (focal sclerosing osteomyelitis) is a REACTIVE bone response to chronic low-grade pulpal inflammation — the associated tooth has a deep restoration or caries and tests non-vital or shows irreversible pulpitis. IDIOPATHIC OSTEOSCLEROSIS (dense bone island / enostosis) is a developmental variant of normal in a tooth with a HEALTHY, VITAL pulp and no restoration. Pulp testing is therefore diagnostic.
• D. Neither lesion expands the cortex; expansion would suggest a different diagnosis entirely.

Note: Condensing osteitis may partially regress after successful root canal treatment. Idiopathic osteosclerosis needs no treatment — just documentation and periodic observation.