| Stainless steel root canal files are widely used in clinical root canal therapy.In the course of root canal therapy,stainless steel root canal files have an indispensable position.Most stainless steel root files belong to ISO standard root canal instruments.Stainless steel root canal files have many advantages in clinical root canal therapy because of their unique rigidity.However,due to the particularity of their working environment,the corrosion resistance and cutting performance of stainless steel root canal files still need to be improved.To improve the corrosion resistance and cutting performance of stainless steel root files.This present work is to deposit TiN and ZrN thin films on stainless steel root canal file surfaces by magnetron sputtering with adjusting deposition time,substrate bias and duty cycle.The thickness,phase composition,hardness and adhesion of the TiN and ZrN films were examined by SEM,XRD and surface hardness and adhesion tests.The corrosion resistance and the cutting performance of the coated root canal files were analyzed by the electrochemical corrosion test and the simulated clinical cutting test.The thickness,phase structure and hardness of the TiN and ZrN films changed with the deposition process parameters.The corrosion current density of stainless steel root canal files coated with TiN and ZrN films decreased significantly compared with that of the uncoated ones.The cutting quantity and efficiency of stainless steel root canal files coated with the optimized process were significantly improved.Compared with the uncoated ones,the stainless steel root canal files coated with TiN and ZrN films improve significantly the surface hardness and corrosion resistance.The stainless steel root canal files optimally coated with TiN and ZrN thin films exhibit the multiple advantages of cutting quantity,cutting efficiency and cutting stability.The cutting efficiency is increased by 60%~75%,and the number of the cut resin root canals is 1.7~2 times in comparison with the uncoated stainless steel root canal files.The remarkable improvements in cutting performance are achieved. |
