It is an established fact that genetic and environmental factors result in variations in the morphology of the dental pulp of human teeth. So, unless the clinician is familiar with the morphology of the roots of all teeth, and the associated intricate root canal anatomy, effective debridement and obturation may be difficult to achieve. Among all the teeth, mandibular first molar is a frequent candidate for root canal treatment and presents many variations. The major variant is the presence of a supernumerary root that can be found distolingually and has a curve at the apex. It is called radix entomolaris, and is found smaller than distobuccal and mesial roots which can be separated or partially fused with these other roots.