Evaluation of shaping ability of ni-ti rotary files working with different motions in simulated root canals with single and double curvature after using pathfinder instruments

Purpose: The purpose of this study is; centering ability and canal transportation of nickel titanium (Ni-Ti) rotary files working in different motion in simulated canal resin blocks simulating single and double curvature human teeth. The comparison of the effect of the Pathfinder Ni-Ti instruments used beforehand with the stereomicroscopic images. Method: In our study, simulated canal resin blocks with sixty single curvatures and sixty double curvatures were used. Simulated canals with single and double curvatures were separated into groups (n = 10) according to the Ni-Ti rotary instruments to be used for preparation and whether or not pathfinders were used before, and ProTaper Next (PTN), TwistedFile Adaptive (TFA), Reciproc (R) along with ProGlider (PG) were used and unused groups were created. For L and S groups; A group: PTN, B group: PTN + PG, C group: TFA, D group: TFA + PG, E group: R, D group: R + PG. Before each simulated canal preparation, black dye was injected into the canal space and preoperative images were taken by stereo-microscope. Each group of resin blocks was prepared with a file group to be tested and according to the manufacturer's instructions and the appropriate type of movement, and post-operative images were taken after injecting red dye into the canal space. Obtained pre- and post-operative images were assessed using computer-assisted superimposition method. The results were compared with each other and the data were evaluated statistically. Result: Conclusion: As a result of statistical analysis, in L canals; It was found statistically significant in the R and R+PG groups that canal transport was obtained the highest compared to PTN, PTN+PG, TFA and TFA+PG groups (p<.05). PTN, PTN+PG, TFA and TFA+PG files were obtained the least canal transport and no significant difference was found between them (p>.05). In the S canals; maximum canal transport was obtained in PTN and R groups. The best centering ability was obtained in the TFA+PG group and there was a statistically significant difference between with the PTN, TFA and R groups (p<.05). Between PTN, PTN+PG and TFA groups and also between R and R+PG groups showed no statistically significant difference (p>.05). In the L and S canals, the expansion amounts of the files were found as R>PTN>TFA. The maximum expansion was obtained in group R and the least expansion was obtained in TFA+PG group and it was statistically significant (p<.05). Discussion: According to the results of the study, canal transport was obtained at various grades in each file group used. The least canal transport in L canals is obtained in PTN, PTN+PG, TFA and TFA+PG groups, and the difference between them can be attributed to the result of the file properties. The maximum deviation in the canal is obtained in the R and R+PG groups, which is a natural result of the taper angle and the file properties that the R file has. When the S canals were examined, the least canal transportation was obtained in the TFA+PG group and no significant difference was found between PTN+PG and R+PG. PTN and R groups showed the greatest deviation from the canal. There was no significant difference between PTN, PTN+PG and TFA. PG files can enhance the centering ability, but it can't completely block the canal transport. No significant difference was found between the PTN and TFA within the boundaries of the study, and the results of the R files created canal transport in the L and S canals. These results suggest that further studies should be carried out in standardized human extracted teeth and more recent canal files. Key words: Nickel-titanium rotary files, shaping ability, canal transportation, centering ability, ProTaper Next, Reciproc, TF Adaptive, ProGlider, Pathfinder, simulated canal, resin block, stereomicroscope