Eficiência de corte de diferentes sistemas endodônticos de NiTi

Abstract

The geometric characteristics of Nickel-Titanium (NiTi) instruments directly influence its cutting efficiency. This study evaluated the cutting of rotary NiTi instruments EndoSequence, Mtwo, GT, GTX, K3, RaCe sizes #20/.06, and PTU F1. Initially, the instruments were characterized with respect to the diameter of the active part, the cross-sectional geometry, rake angle, helical and cutting angles. The cutting efficiency tests were performed on bench device where five sets of each type were tested in acrylic blocks prefabricated containing an artificial canal previously explored with manual files # 10 and # 15. The motor was set at a speed of 300 rpm and torque 5 Ncm and the instruments were inserted into the canal at a constant speed of 0.09 mm / sec. While a load cell recorded the axial force exerted, a multimeter recorded the torque required by the instrument along the 17 mm of artificial canal. The instruments ES, Mtwo, GTX and RaCe had lower axial force when compared with K3, GT and F1 instruments, possibly related to the cross-sectional geometry and the helical angles. The instruments GT and F1 showed a greater torque when compared to the others instruments. The torque required by the instruments is directly related to the cross-sectional geometry, cutting angles and helical angles. Instruments with lower axial force values and lower torque values have better cutting efficiency.