Evaluation of surface topography changes in three NiTi file systems using rotary and reciprocal motion: An atomic force microscopy study.

AIM To evaluate the surface topography changes in three nickel-titanium (NiTi) file systems using either rotary or reciprocal motion using atomic force microscopy (AFM), and to determine the effect of scanning area on the AFM results in this study. METHODOLOGY Five points on a F2 Protaper file, R25 Reciproc file, and a Primary file from WaveOne systems were scanned preoperatively in 1 × 1 and 5 × 5 µm(2) with an AFM device that can scan an intact (not sectioned) file. One standardized resin block was used for each instrument, according to the manufacturer's recommendations. Points were re-scanned postoperatively using the same AFM and settings. Root-mean-square (RMS) and roughness average (Ra) values were obtained. The preoperative and postoperative surface topographies were compared separately in terms of RMS and Ra values. The surface topography change scores were analyzed using Kruskal-Wallis and Mann-Whitney U tests using a 0.10 significance level. RESULTS There were no significant differences preoperatively among the NiTi file systems in 1 × 1 or 5 × 5 µm(2) areas. Postoperatively, the WaveOne Primary had more surface irregularities (significant for 5 × 5 µm(2) scan in Ra evaluation). CONCLUSIONS Three-dimensional AFM images of instrument surfaces showed topographic irregularities preoperatively and postoperatively. AFM results differ depending on the scanning area and file used.