A Comparative Study to Evaluate Canal Transportation and Centering Ratio at Different Levels of Simulated Curved Canals Prepared by iRaCe, ProTaper NEXT and ProTaper Universal Files

Background: Root canal preparation includes both shaping and enlargement of the endodontic space in conjunction with its disinfection, without any procedural error is of the utmost preference. Recently, in endodontic practice, the nickel-titanium instruments are used commonly for preparation of the root canal space. Nickel-titanium instruments are much more flexible than stainless steel files and have superior cutting efficiency. Aim of this study was to measure and compare the canal transportation and centering ability of iRaCe and ProTaper NEXT nickel titanium instruments with ProTaper Universal instruments in simulated curved canals at different levels and compare canal transportation and centering ability among different levels for each tested instrument. Material and Methods: Sixty simulated curved canals of 40°curvature were randomly divided into three groups of twenty canals each; the first group (group A) was prepared with iRaCe instruments, the second group (group B) was prepared with ProTaper NEXT instruments and the third group (group C) was prepared with ProTaper Universal instruments. The canals were prepared to an apical size 30 by crown-down instrumentation technique. Removal of material was measured at five different levels: at the canal orifice (O), half way to the orifice in the straight sections (HO); the beginning of the curve (BC); the crest of the curve (AC); the end point (EP). Preand post-operative photos of the simulated canals were taken in a standardized technique at magnification of 40X. An assessment of canal shape has been determined using Photoshop CC 2014 and AutoCAD 2014 software program. The data of canal transportation as well as centering ratio were analyzed statistically using Shapiro-Wilk, ANOVA and LSD tests. Results: the results of this study demonstrated that the iRaCe instruments showed a significantly less canal transportation and a significantly better centering ability than both ProTaper NEXT and ProTaper Universal instruments at all levels of measurements, followed by ProTaper NEXT instruments that showed a significantly less canal transportation and significantly better centering ability at all levels when compared with ProTaper Universal, while the ProTaper Universal instruments showed the highest values of canal transportation and the worst ability to stay centered in the canals at all levels. Considering the direction of canal transportation, the iRaCe instruments showed minimal transportation towards inner aspect of canal at coronal and at the apex of curve and towards outer aspect of canal at middle, beginning of curve and at the end point of the preparation, while ProTaper NEXT instruments were showed transportation usually towards the inner aspect of the canal at middle part of the canal and towards the outer aspect at coronal, beginning of curve, apex of curve and at the endpoint of the preparation, while ProTaper Universal files were usually towards the inner aspect at middle part of the canal and towards the outer aspect at coronal, beginning of curve, apex of curve and at the endpoint of the preparation. Conclusion: The study demonstrated that canal preparation with the three files of Ni-Ti instruments produced canal transportation. The iRaCe file showed less canal transportation and better centering ability than ProTaper Next and ProTaper Universal groups at all the five measuring levels, followed by ProTaper NEXT, while the ProTaper Universal files showed the least centering ability and increased straightening and canal transportation at all the five measuring levels especially at the apical portion of the canal. [Al-Gharrawi HA, Fadhil MA. A Comparative Study to Evaluate Canal Transportation and Centering Ratio at Different Levels of Simulated Curved Canals Prepared by iRaCe, ProTaper NEXT and ProTaper Universal Files. J Am Sci 2016;12(10):103-115]. ISSN 1545-1003 (print); ISSN 2375-7264 (online). http://www.jofamericanscience. org. 15. doi:10.7537/marsjas121016.15.