Endodontic Failure Causes — NDEB AFK MCQ
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Correct answer: A — Coronal microleakage and persistent intracanal infection
The primary cause of endodontic failure is persistent intracanal infection due to inadequate debridement (missed canals, untreated areas of the canal system) combined with coronal microleakage (loss of coronal seal allowing recontamination). Studies by Siqueira and Nair demonstrate that persistent bacteria (particularly Enterococcus faecalis in retreatment cases) in the root canal system are the main reason for treatment failure. Coronal restoration quality is as important as the obturation quality.
Reference: Torabinejad – Endodontics: Principles and Practice, 6th ed., 2021