Which tooth most commonly presents with accessory canals?

Correct answer: A. Maxillary first molar (#14)

• A. Correct (keyed). The maxillary first molar's mesiobuccal root (with its frequent MB2 and high accessory/lateral canal incidence) is the classic example of complex canal anatomy.
• B. Mandibular first molars also have abundant furcation accessory canals — a reasonable real-world alternative — but the keyed answer is the maxillary first molar.
• C. The maxillary central incisor is usually a single straightforward canal.
• D. The mandibular canine is usually simple.

Note: Both maxillary and mandibular first molars are rich in accessory canals; the keyed answer is the maxillary first molar.