The shape of a trapezoidal access cavity is associated with which tooth?

Correct answer: C. Mandibular first molar

• A. Maxillary central incisor access is typically triangular.
• B. Maxillary first molar access is typically rhomboidal or trapezoidal but different from the mandibular pattern.
• C. Correct. The mandibular first molar access cavity is classically trapezoidal in shape — wider mesially (to access the two mesial canals) and narrower distally, reflecting the typical root canal anatomy.
• D. Mandibular second molar access may be more oval or rectangular depending on root morphology.