A comparison of shaping ability of three different contemporary rotary systems in curved root canals

The aim of this study was to evaluate the degree of transportation, working time and procedural errors during the preparation of root canals having 20° - 40° curvatures using different rotary systems with different kinematics and metallurgic properties. The mesial roots of 60 mandibular molar teeth with completely developed root apices , no previous endodontic treatment and having 18 mm. working lengths were used. After 18 mm. decoronization of the teeth, endodontic access cavities were prepared using round burs.The radiographs were taken with 10 and 15 no. K-files before the preparation.The sample teeth were divided into 3 homogeneous groups according to their curvature angles and radii of curvature . In the first group, the teeth were prepared with WaveOne primary instrument and the radiograph were taken with the same file after the preparations were completed. In the second group, the teeth were prepared with OneShape instrument and the radiographs were taken with the same file after the preparations were completed. In the third group, the teeth were prepared with Twisted File Adaptive SM1 and SM2 and the radiographs are taken with SM2 file after the preparations were completed. Standardized radiographs were taken according to modified Bramante's technique [1] before and after instrumentation. For the analysis of the radiographs, all the radiographs were printed on tracing papers with x10 magnification. The contours of the teeth and the reference objects were superimposed and the angle between the tips of the two files were measured for the calculation of the amount of straightening. Statistical analysis was performed using SPSS (Statistical Package for Social Sciences) for Windows 15.0 program.Because quantitative values showed parameters with normal distribution, the comparison of intragroup parameters was performed using Oneway ANOVA test.For the determination of the group which led to differences, Tukey HSD test was used.Statistical significance level was evaluated at p<0,05 . While the WaveOne group had the highest value of straightening with 1,28± 0,27 degrees, OneShape group caused 1,06 ± 0,30 degrees of straightening and the best result was obtained with the Twisted File Adaptive group with 0,99 ± 0,29 degrees of straightening.The difference between the results of TFA and OneShape group was found to be statistically insignificant.When the working times of the groups were evaluated, the single file system OneShape showed the least working time with 51,40 ± 2,28 seconds, followed by the Wave One group with 58,95 ± 4,68 seconds. Working time was the longest with the TFA group which included 2 files for the preparation. Procedural errors such as loss of working length, ledge formation, perforation and file fracture that can occur during root canal preparation were not observed in any group. It can be concluded that during the preparation of curved root canals, WaveOne, OneShape and TFA rotary systems can be recommended to complete the root canal treatment safely and quickly.