Mandibular first and second molar. The variability of roots and root canal system.

The root and canal anatomy of mandibular first and second molars has normally recurring features, as well as a great number of atypias. Normally mandibular first and second molars have two roots, one is mesial and the other is distal, and at least three main canals. The roots of the second molar can change from one to three, the first molar can have also four roots; the canals can change from three to even six. The conventional root canal anatomy indicates the location of the initial access. The knowledge of both the normal and abnormal anatomy of molars shows the parameters under which root canal therapy is to be executed and can directly modify the probability of success. This is the reason why endodontists must be familiar with all abnormalities as well as their percentage. We present a review of the modern literature about the event of aberrances with references to the number and morphology in mandibular first and second molar root and root canals.