Aim: The aim of the present study was to compare the cutting efficiency of XP-Endo shaper and iRaCe nickel titanium rotary instruments after different number of uses and to evaluate the surface characteristics.
Methodology: Forty-eight mesial roots were divided into two groups (n= 24) according to the type of the file system used (XPS/iRaCe) and was then subdivided into three subgroups (n=8) according to the number of uses (first use, second use and third use). Each specimen was prepared and irrigation was done using 5 ml of freshly prepared 2.5% NOCL, then 3 ml of 17% EDTA followed by 10 ml of distilled water. All root samples were weighted before and after preparation and weight loss was calculated. Two samples (Size 30 and Taper 0.04) from each file system were randomly selected and photographed using Scanning Electron Microscope (SEM) before and after the third use, at magnification 150x and 2000x. Comparing the cutting efficiency of each group at the different number of uses was done using analysis of variance (ANOVA) with multiple comparisons post hoc test.
Results: There was statistically significant difference between XPS and iRaCe after each use (P≤0.05), with drop in the cutting efficiency in both groups after second and third use, and no statistically difference between second and third use (P>0.001). SEM examination of unused files showed manufacture defects, while files after third use showed other defects.
Conclusions: XPS showed higher cutting efficiency than iRaCe, with reduction in its cutting efficiency after multiple use.