Clinical study in preparation of C-shaped root canals in mandibular molars between ultrasonic instrument and stainless K files

AIM:To compare the clinical effects between ultrasonic instrument and stainless K files in preparation of C-shaped root canals in mandibular second molars.METHODS: Fifty mandibular second molars with C-shaped root canals scheduled with root canal treatment were divided into two groups in random principle.In experimental group(n=25),root canals were prepared with Odontoson-M ultrasonic instrument as manufacture's instruction.Canals prepared with K Flexofiles by hand as control group(n=25).The time of preparation of each tooth was recorded.All teeth were obturated with lateral condensation method and were taken radiograph to analyze the efficacy of preparation and obturation.The incidence of EIE(Endodontic interappointment emergencies) was observed.RESULTS: The mean prepared time of experiment group is 340s,which is significantly less than the control group(620s).There were two apical ledges in the experiment group and three in the control group.In addition,three apical blockages and three apical transportation were found in the control group.Compared with the control group,incidence of EIE was not significantly increased in the experiment group.CONCLUSION: Compared with K Flexofile,ultrasonic instrument can prepare the C-shaped root canal more effective,easy and safe.