Wear of Nickel-Titanium Endodontic Instruments Evaluated by Scanning Electron Microscopy: Effect of Ion Implantation

Abstract

The present work analyzes possible increases in resistance to wear of nickel-titanium endodontic instruments that have undergone a process of ionic implantation. ProFile .04 taper #25 instruments were subjected to ionic implantation with bands of nitrogen ions of 250 KeV, currents in the order of 10 microA/cm2, and doses of 2 x 10(17) ions/ cm2. The instruments were used to make preparations in acrylic endodontic training blocks. Scanning electron microscopic investigations showed that after 60 s of work inside the endodontic training blocks nonionic implanted control instruments showed small modifications in their blades, and their tips showed the first signs of wear. After 240 s the control instruments showed consistent signs of wear and frequent changes to their surfaces. After 240 s of use the ionic-implanted instruments did not present any significant changes in the micromorphology of their surfaces. The implanted instruments did not manifest the typical signs of wear and did not show the surface changes that quickly affect the working life of untreated endodontic instruments manufactured from nickel-titanium.

Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

“…Shortly afterwards, the simulated canal was instrumented with a 15-caliber Flexofile manual instrument up to the CRT. The ProTaper S1 instrument was used until it encountered resistance, via 6 insertions of 10 seconds each in the interior of the simulator canal, up to a total time of 60 seconds [12]. Then, the SX instrument was used passively until encountering resistance, again via 6 insertions of 10 seconds each, up to a total time of 60 seconds [12].…”

“…Although the introduction of nickel-titanium (NiTi) instruments seemed to overcome this difficulty [1], the preparation of curved root canals results in morphological alterations, including wear, disappearance of the cutting edge, microfractures, and surface defects, to the instrument surface [2][3][4][5][6][7]. New surface treatment methods, such as ion implantation and plasma nitriding, have been investigated to improve the properties of these instruments and extend their life [8][9][10][11][12].…”

“…Most studies of nitrogen ion implantation have investigated implantation at doses of ~10 17 nitrogen ions/cm² [8][9][10][11][12]. In these studies, ion implantation produced better outcomes compared to nitrided or untreated instruments [8][9][10][11][12].…”

“…In these studies, ion implantation produced better outcomes compared to nitrided or untreated instruments [8][9][10][11][12]. Nitrogen ion implantation creates a layer of titanium nitride on the surface of components by using a low-energy accelerator (~100 to 400 keV) to bombard the NiTi surface with nitrogen ions [12].…”

“…Nitrogen ion implantation creates a layer of titanium nitride on the surface of components by using a low-energy accelerator (~100 to 400 keV) to bombard the NiTi surface with nitrogen ions [12]. Nitrogen doses of 10 17 ions/cm² may produce titanium nitride layers of up to 100 nm thick [12].…”