Replica 30-001 is a classic four-canal mandibular first molar. It’s large pulp chamber makes it an ideal replica to practice mandibular molar access procedures. While the coronal half of these four canals are large and uncomplicated, at mid-root in the distal, the large ovoid canal bifurcates into DB and DL canals with smooth distal curvature but significant lateral irregularity. The DL canal is easily negotiated after you find the point of bifurcation and begin directing instruments to one side or the other. However, the apical morphology of the DB canal is complex—having a primary canal path that curves in a smooth distal direction but has a lateral canal exiting B and L in its last 2mm from length in the primary canal. The mesial canals also have apical irregularity, making this an excellent replica to learn impediment identification, file bending, and the mental imaging skills required to traverse these fairly minor impediments.