Mandibular Premolar Second Canal — ORE Part 1 MCQ
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Correct answer: A — Mandibular first premolar
The mandibular first premolar has the highest incidence of a second canal at approximately 23.55% in single-rooted forms. This tooth is notorious in endodontics for anatomical complexity and variability. Although most mandibular premolars have a single root, nearly one quarter of first premolars possess two distinct canals requiring identification and treatment. In contrast, mandibular second premolars have only 2.8–3.6% incidence of two canals, and anterior teeth (incisors and canines) are overwhelmingly single-canal, with maxillary central incisors showing only 0.6% additional canal prevalence. This anatomical distinction makes the mandibular first premolar the definitive answer and reflects a key endodontic curriculum point for examination candidates.
Reference: Cleghorn BM, Christie WH, Dong CC. 'Root Anatomy and Root Canal Configuration of Human Permanent Mandibular Premolars: A Systematic Review.' Journal of Endodontics. 2013. PMC3881342; supported by Vertucci FJ anatomical studies and contemporary CBCT prevalence data. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881342/