NiTi loss on the dentinal walls and instrument deformation during root canal preparation.

The purpose of this study was to quantify the presence of nickel (Ni) and titanium (Ti) on dentin walls of prepared root canals using Endosequence (ES) and Wave One (WO) systems, the deformation, and fracture of these instruments. Thirty extracted human premolar teeth were selected and prepared with WO, ES, and manually (control group-CG). Each instrument was used in four root canals. The root canals were irrigated with 2.5% sodium hypochlorite solution. After preparation, roots were sectioned longitudinally and the apical third was analyzed by scanning electron microscopy with X-ray microanalysis (SEM-EDS). The percentage of Ni and Ti found on dentin walls was compared using Kruskal-Wallis test and post hoc Dunn. The instruments deformation and fracture was evaluate by SEM before and after use. Spiral distortion, fractures, and surface wear were compared using Mann-Whitney test. The level of significance was set at 5%. Ni and Ti were found on the dentin walls of the apical root canal for ES and WO systems (p > .05). No distortion in the spirals and no instrument fracture were observed. Regarding to surface wear, most of the instruments scored as moderate wear (p > .05). This study concluded the WO and ES presented Ni and Ti loss. In addition, the preparation of four root canals did not caused irreversible deformation in WO and ES instruments.