skip to main content

Missed Canal Radiographic Sign — NDEB AFK MCQ

Instant feedback + full explanation. One question, done properly.

HardEndodonticsMissed Canal Radiographic SignNDEB AFK

Which of the following radiographic signs on a periapical radiograph indicates that a root canal treated tooth may have a missed canal contributing to persistent periapical radiolucency?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — An eccentric or off-centre root canal obturation (fill not centred within the root outline, suggesting another canal exists on the opposite side)

An eccentric or off-centre root canal obturation on a periapical radiograph — where the filled canal is not centred within the root outline — strongly suggests the presence of an additional unfilled canal on the opposite side (the missed canal displaces the centre of the filled canal toward one side). This is particularly common in mesial roots of mandibular molars (missed second canal) and mesiobuccal roots of maxillary molars (missed MB2). Persistent periapical radiolucency after apparently adequate RCT should prompt investigation for missed canals (CBCT, microsurgical exploration, retreatment).

Reference: Torabinejad – Endodontics: Principles and Practice, 6th ed., 2021