Clinical Study Of C-shaped Root Canal System Of Mandibular Second Molars

Objective: The purpose of the study was to study the incidence rate, clinical diagnoses and treatment method of C-shaped root canal system of mandibular second molars.Methods: Collect ten clinical cases, take preoperative radiographs, and analyze the ten cases of disease, according to the improved diagnostic criteria of AC-Fouzan and the radiograph separate criteria which was proposed by Fan Bing. Open the camera pulp, clear the pulp chamber. Analyze the types of root canal orifices, according to the root canal orifice separate criteria which was proposed by Melton. As for the cases whose anatomic forms were complicated, such as preoperative radiographs could not judge the drom-shape of the middle and below segment of root canal, we could use the initial apical file(IAF)to judge the anatomy typing of the middle and below segment of root canal of mandibular second molars. Use ethylenedi-amine tetra-acetic acid(EDTA)to clear the root canal, step-back technique to prepare root canal, and fill root canal firmly. Take posto- perative radiographs, record the incidence rate of C-shaped root canal and clinical feature, and evaluate the therapeutic effect.Results: In the ten clinical cases, there were eight cases who represent cone confluence root in the preoperative radiographs;there were two cases which represented apud-midst independent root canal. The number of the cases which showedâ… pattern in X-ray classification was five; the number of the cases which showedâ…¡pattern in X-ray classification was three; the number of the cases which showedâ…¢pattern in X-ray classification was one; other was one. The number of the case which showed C1 pattern was five; C2 pattern was three; C3 pattern was one; there was also one case which showed one single enlarge round root canal orifice. All of the trouble teeth were gained the all-right therapeutic efficacy.Conclusion: The C-shaped root canal systems of mandibular second molars mainly reside in confluence root, the most common pattern is the cone confluence root. The most common root canal orifice shape is C1 pattern, the second one is C2 pattern, and the C3 pattern is the last one. X-ray image of some mandibular second molars show cone-shaped con- fluence root, but the root canal system may not be C-shaped root system. It may be the unity round bulky root canal, or other type canal system. Although the anatomic form of C-shaped root system is complicated, and the diagnoses and the treatment are more difficult than the common ones, we can diagnose the C-shaped root canal system exactly by checking root canal orifice, taking preoperative radiographs and using initial apical file. We can also gain satisfactory therapeutic efficacy of C-shaped root canal by using EDTA to clear root canal, preparing root canal by step-back technique, filling root canal firmly.