Study of C-Shaped Root Canals in Mandibular Second Molars in Vitro

Objective: The aim of this study was to search a kind of effective instrument for preparation the C-shaped root canals and improve the healing rate of mandibular second molars.Methods: 80 mandibular second molars were extracted and randomly divided into 4 experimental groups.Group 1 were prepared by SS-K file;group 2 were prepared by SS-K file combined PF,group 3 were prepared by NT,group 4 were prepared by ultrasonic root canal instrumentation.All root canals were filled by warm vertical condensation using Vitapex paste and gutta percha point.Effect of filling was evaluated by apical microleakage and digital X ray shows.Results: Among the different instrumentations,the group 2 and group4 have the least microleakage.But there were no significant difference between the group 2 and group 4(P0.05).Conclusion: SS-k file combined PF or ultrasonic root canal instrumentation is the effective instrument for preparing the C-shape root canals.