Approximately what percentage of mandibular first premolars have two canals?

Correct answer: A. About 25%

• A. ✅ CORRECT — Roughly a QUARTER (Vertucci reports about 25.5%) of mandibular first premolars have more than one canal, most often a Type V configuration in which a single canal divides in the apical third. That bifurcation is frequently missed and is the reason this tooth has one of the higher endodontic failure rates.
• B. ❌ 80% is far too high for any premolar; it approaches the MB2 figure for maxillary first molars.
• C. ❌ 5% is closer to the figure for the mandibular SECOND premolar (roughly 2.5–12%).
• D. ❌ 55% overstates it substantially.

Note: Mandibular first premolar: the most anatomically unpredictable premolar. Suspect a second canal when the main canal 'disappears' mid-root on the radiograph.