The surgical treatment of a case of anesthesia that occurred with the extrusion of Endomethasone root canal sealer into the mandibular canal is presented. Endomethasone is a neurotoxic root canal sealer containing paraformaldehyde and eugenol. The literature indicates immediate surgical decompression on the extrusion of Endomethasone into the mandibular canal. In our case, the decompression surgery was done 3 weeks after the endodontic mishap. The nearly complete resolution of anesthesia 4 months following the decompression surgery suggests that the neurotoxic effects of Endomethasone are still reversible after 3 weeks.