Endodontics · single question
How many canals does the mandibular first molar have, and how many canals are in the mesial root?
Show answer and explanation
Correct answer: C. 4 total canals; mesial root has 2 canals
The mandibular first molar most commonly has THREE roots (two mesial roots, one distal root — in some classifications) but TWO anatomical roots (mesial and distal). The standard configuration is: Mesial root = 2 canals (mesiobuccal + mesiolingual), Distal root = typically 1 canal (sometimes 2). Total = most commonly 3–4 canals. The classic answer is 3 canals (2 mesial + 1 distal) but the most clinically accurate is 3-4. For INBDE: 3 canals total, with 2 in the mesial root.
- A. Partially correct but incomplete. 3 canals (2 mesial + 1 distal) is the most common textbook answer. The mesial root does have 2 canals — this is correct.
- B. Incorrect. The mesial root of the mandibular first molar almost always has 2 canals (MB and ML) — having only 1 would be atypical.
- C. CORRECT. The most accurate answer: 3-4 total canals (commonly 4), with 2 canals in the mesial root (mesiobuccal and mesiolingual).
- D. Incorrect. One canal per root greatly underestimates the canal anatomy of the mandibular first molar.