Negotiation of C-Shaped Canal Systems in Mandibular Second Molars

Introduction: The purpose of this study was to investigate the method of canal negotiation in the presence of differently C-shaped orifices using the micro-computed tomography technique. Methods: Forty-four extracted mandibular second molars with C-shaped roots were collected from a Chinese population. Size 10 or 15 K files were used to explore the canal orifices when viewed under the surgical operating microscope. Choices in the number and position of the files inserted into the canal system were based on the different orifice shape. After the teeth with files were scanned and reconstructed, the number and position of the files were analyzed. Results: Among 44 teeth, a total of 132 initial files were inserted into 83 orifices, in which 42 orifices had only one initial file, 33 with two, and 8 orifices had three files inserted. Eight main canals were not located because of canal bifurcations in the root, calcification, and dentin fusion. Conclusion: This new method for negotiation combined with careful exploration may provide an effective way for indentifying the nature of the canal system and enhancing debridement in these complex canal anatomies. (J Endod 2009;35:1003-1008)