A general dentist tried to perform root canal treatment on tooth 13. They reported to keep getting stuck. They took a cone beam and saw the lingual canal had a hook that went towards the mesial then to the palatal. They sent the patient to me and she was still in pain especially to cold and biting. I diagnosis tooth 12 causing cold/biting pain and tooth 13 hurt constantly. I performed both treatments with the EdgeEndo files .04 taper. The EdgeEndo file scouted out and around the calcified lingual canal like a hot knife through butter. I was very impressed and was not concerned about file breakage. I used it for tooth 12 also. Both teeth had canal lengths of 25mm.