Effect of Nitrogen Ion Implantation on the Flexibility of Rotary Nickel-Titanium Instruments

Abstract Introduction The aim of this study was to assess the effect of nitrogen ion implantation on the flexibility of rotary nickel-titanium (NiTi) instruments as measured by the load required to bend implanted and nonimplanted instruments at a 30° angle. Methods Thirty K3 files, size #40, 0.02 taper and 25-mm length, were allocated into 2 groups as follows: group A, 15 files exposed to nitrogen ion implantation at a dose of 2.5 × 10 17 ions/cm 2 , voltage 200 KeV, current density 1 μA/cm 2 , temperature 130°C, and vacuum conditions of 10 × 10 −6 mm Hg for 6 hours; and group B, 15 nonimplanted files. One extra file was used for process control. All instruments were subjected to bend testing on a modified troptometer, with measurement of the load required for flexure to an angle of 30°. The Mann-Whitney U test was used for statistical analysis. Findings with P Results The mean load required to bend instruments at a 30° angle was 376.26 g for implanted instruments and 383.78 g for nonimplanted instruments. The difference was not statistically significant. Conclusions Our findings show that nitrogen ion implantation has no appreciable effect on the flexibility of NiTi instruments.