Bifid mandibular canals are common anatomical findings with variations based on direction and location of branching, which carry significant clinical implications for endodontic and surgical dental procedures. This case study describes a previously unreported ectopic dental canal that branches off the superior border of the mandibular canal, enters the apex of a mandibular second molar, traverses through the root, anastomoses with the root canal system, and subsequently exits through the lingual aspect of the root. The anastomosis of this ectopic dental canal with the mesial lingual canal led to significant bleeding during rotary instrumentation. This unique anatomical variation demonstrates the importance of a thorough cone-beam computed tomography analysis to identify critical structures prior to undertaking dental procedures involving the root apices of mandibular posterior teeth and adjacent areas.