Efficiency of third root canal in the distal root of the mandibular first molar

Objective: To observe if there is the existence of a third root canal in the distal root of the mandibular first molar so as to avoid the clinical treatment of mandibular first molar root canal in the distal root left to provide guidance.Methods: Choice the lower the distal root canals and combining with X-ray technology to determine the number of distal root canals in the mandibular first molar.Results: There were 2 cases found distal third root canals among 172 cases of the lower first molars.Conclusion: The existence of the distal third root canal in the lower first molar,which increased by the emergence of root canal missed chances in the clinical treatment,so it is very important to double-check the number of root canals when operating root canal treatment.