Comparison of efficiency of current rotary systems according to the different parameteres

The purpose of this in vitro study was to compare the root canal preparations performed by using GT Series X and TwistedFile systems produced by new manufacturing methods, Revo-S, RaCe, Mtwo and ProTaper Universal systems manufactured directly from conventional nitinol, and stainless steel K-Flexofile instruments on the teeth which had between 30° - 40° curvature angle and 4 ? 9 mm curvature radius of the root canal.For this purpose; the mesiobuccal root canals of the 140 upper first permanent molar teeth were used. After root canal preparations made by using GT Series X, TwistedFile, Revo-S, RaCe, Mtwo and ProTaper Universal NiTi rotary systems and stainless steel K-Flexofile instruments, transportation occured in the root canal and alteration in working length were assessed by a modified double-digital radiographic technique (Maggiore technique). It was found that NiTi rotary systems caused less canal transportation and alteration of working length than stainless steel instruments. There was no significant difference between NiTi rotary system groups at any levels except 2.5 mm from the working length. At this level ProTaper Universal system caused significant canal tansportation.The amounts of debris and smear layer were quantified on the basis of a numerical evaluation scale using SEM photographs for these NiTi rotary systems and stainless steel instruments. Complete cleanliness was not achieved by any of the techniques and devices investigated. No difference was observable between instrumentation groups. Moreover, on average the apical third of the canals was less clean than the middle and coronal thirds regardless of the instrument used.It could be accepted that both NiTi rotary instruments maintained the original canal shape better than the K-Flexofiles and were able to provide satisfactory cleaning, similar to that obtained by the manual instrumentation technique.The results indicated that newly designed GT Series X and TwistedFile systems were only as effective as the conventional ones. Therefore, it could be predicted that to instrument root canals which had different anatomical variations more better, the development of the instruments that adapt to the cross-section of the root canal is required.