Oral Surgery · single question
A fractured mandibular third molar is being extracted. The intraoral radiograph shows the apex close to the inferior alveolar canal. Which nerve is at GREATEST risk of paresthesia?
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Correct answer: C. Inferior alveolar nerve
When mandibular third molar roots are radiographically close to the inferior alveolar canal (IAN), the inferior alveolar nerve is at greatest risk of injury, leading to numbness or paresthesia of the lower lip, chin, and mandibular teeth on that side. The lingual nerve is also at risk (especially from retraction) but is not visible on radiograph as the concern here is root proximity to the IAN canal specifically.
- A. ❌ The long buccal nerve supplies buccal soft tissue adjacent to lower molars and is at low risk in this scenario.
- B. ❌ The mental nerve is a terminal branch of the IAN that exits at the mental foramen — at risk if the foramen is in the surgical field, but not specifically related to third molar root proximity.
- C. ✅ CORRECT – When roots are close to the IAC on radiograph, the inferior alveolar nerve is at greatest risk for paresthesia.
- D. ❌ The lingual nerve is at risk during soft-tissue retraction but is NOT what the radiograph is showing proximity to.