C-Shaped Canal Lower Second Molar — ORE Part 1 MCQ

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ModerateEndodonticsC-Shaped Canal Lower Second MolarORE Part 1

Which of the following teeth is most likely to have a C-shaped canal system?

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Correct answer: A — Mandibular second molar

The mandibular second molar is the tooth most likely to present C-shaped canal anatomy. Multiple international prevalence studies using cone-beam computed tomography document C-shaped canals in approximately 10–14% of mandibular second molars globally, with much higher rates in Asian populations (up to 44%). In contrast, C-shaped canals are essentially absent in incisors and canines, and rare in maxillary premolars. First mandibular molars show C-shaped canals in only 0.2% of cases. The C-shaped canal is named for its crescent morphology in cross-section, typically arising from fusion of the mesial and distal root canals with a continuous lingual groove. This anatomical variation is clinically significant because the complex and unpredictable internal anatomy requires careful treatment planning, advanced imaging (CBCT), and modified instrumentation and obturation techniques. Recognition of this anatomy in mandibular second molars is essential endodontic knowledge.

Reference: Worldwide Prevalence of Mandibular Second Molar C-Shaped Morphologies Evaluated by Cone-Beam Computed Tomography. International Endodontic Journal 2017. https://pubmed.ncbi.nlm.nih.gov/28734652/; corroborated by: Prevalence and morphology of lower second molars with C-Shaped canals: A CBCT analysis. 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11907342/