Análise ultraestrutural da característica de superfície em relação à presença de rebarbas em instrumentos rotatórios com diferentes acionamentos e tempos de uso

Abstract

The objective of this study was to evaluate the presence of burrs on the surfaces of rotary endodontic instruments using Scanning Electron Microscopy (SEM) operated manually and by an electric motor at different times of use. 40 X2 instruments (25/06) from the X-Gray® system were used and were initially evaluated using the Scanning Electron Microscope (SEM) before first use. 40 mesial roots of lower molars were selected with a degree of curvature between 20° and 40° and a radius of curvature ≤10 mm distributed into two groups, Group 1, instrumentation with SX files for cervical and middle preparation and X2 for shaping the third. apical by means of the electric motor and in Group 2, these instruments were coupled to the Ed File® manual adapter to perform the instrumentation and in both groups rotational kinematics was used and each instrument was used on two roots. To standardize the position of the instrumentation, a silicone block was made and fixed in a bench vise. The working length of the mesial canals was defined at 0.5 mm short of the apex. After each use, new electron micrographs at the tip of the instrument at 2 mm and 4 mm with 180x magnification were taken to evaluate the presence of burrs, where these defects were measured using the Fiji ImageJ program. 2.5% sodium hypochlorite was the irrigating solution used, with 1 ml being used for each insertion of the instrument. The data were subjected to statistical analysis, indicating a significant statistical difference (P<0.05) in the 4th mm region of group 1 when compared to the other locations, that is, the burrs present/absent in this region were much larger than the different areas evaluated. It can be concluded that the 4th mm was the area that showed the most burr-type defects, especially after the first and second use and the manual adapter is a good option for activating rotary instruments.