Radix Entomolaris: A Clinical Challenge.

A major anatomical variant of the two-rooted mandibular first molar is a tooth with an additional distolingual third root: The radix entomolaris (RE). It is essential to anticipate and find all roots and canals during root canal treatment. Proper angulations and interpretation of radiographs help to identify pulp chamber and root anatomy. If present, an awareness and understanding of this unusual root and its root canal morphology can contribute to the successful outcome of root canal treatment.