Análise das características de superfície e desvio apical promovido por instrumentos rotatórios após uso em canais simulados - Estudo in vitro

Abstract

The aim of this study was to compare two rotary instrumentation systems in simulated curved canals, evaluating their surface characteristics, apical deviation, and instrument wear after use. A total of 30 simulated canals, manufactured in transparent resin blocks with standardized curvature angles of 32o, a curvature radius of 3 mm, and a length of 16 mm, were selected, along with 30 endodontic instruments divided into two groups. In Group 1, fifteen 25.06 instruments from the Logic system were used, while in Group 2, fifteen 25.06 instruments from the VDW Rotate system were employed, each used only once. Each instrument was analyzed before and after its first use using a Scanning Electron Microscope (SEM) at 190x magnification to assess surface characteristics, particularly the presence of burr-type defects, in three distinct areas: the tip, the 2nd mm, and the 4th mm from the tip. Additionally, the instruments were weighed using an analytical electronic balance. The simulated canals were instrumented 0.5 mm short of the working length with the aid of an endodontic motor, using a reciprocating motion and irrigated with 2.5% sodium hypochlorite. To evaluate apical deviation, each resin block was photographed before and after instrumentation, and the images were superimposed to measure deviation at the 1st, 2nd, 3rd, and 4th mm of the apical third. The blocks were weighed before and after instrumentation to assess wear after chemomechanical preparation. Statistical analysis revealed a significant difference (p < 0.0001) in instrument weight between the groups before and after instrumentation. However, no significant changes were observed in the weight of the resin blocks (p > 0.05). All instruments exhibited alterations in surface characteristics, and the burr defect areas varied at specific points, with a reduction in burr extension. Additionally, the VDW Rotate instruments demonstrated a more uniform surface finish. No statistically significant differences were found in apical deviation analysis (p > 0.05). In conclusion, the rotary systems studied demonstrated satisfactory performance during root canal instrumentation. Despite some superficial defects, thermally treated NiTi systems are currently a safe and effective option for endodontic treatment.