Root Canal Anatomy — ORE Part 1 MCQ
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Correct answer: D — Single canal (Type I Vertucci)
Answer: A. Single canal (Type I Vertucci). Mandibular premolars typically present with a single root and single canal. Multiple robust CBCT studies (Thai, Saudi, Bengali, Israeli, and North American populations) consistently demonstrate Type I is the most common configuration, with prevalence ranging from 63–98% depending on the tooth (second premolars closer to 98%). The clinical scenario—one canal orifice identified—is consistent with Type I anatomy. Distractors B (Type IV: two separate canals with two apical foramina) and D (three canals) would present as multiple distinct orifices. Option C (Type II: one canal splitting into two) would eventually divide but is much less common (~3–5% in mandibular premolars). Option E (C-shaped) occurs in <10% of mandibular premolars and is considered a morphological variant. For examination purposes, Type I is the standard expected anatomy and the best answer to the question of 'most common' configuration.
Reference: Multiple recent CBCT studies: Thai population (2020, ); mixed population (2023, ); Bengali subpopulation (2024, ); systematic review (2013, ). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8444426/