This tooth is similar to the mandibular first molar, although a little more compact. The mesial canals tend to lie much closer together, and the incidence of two canals distally is much less. This tooth seems to be more susceptible to vertical fracture. Occasionally, the root canals may join in a buccal fin giving a C-shaped canal, which may lead all the way to the apex. The access cavity is similar to that of the first molar.