Isfahan University of Medical SciencesDental Research Journal1735-33279320120821A novel approach to determine the effect of irrigation on temperature and failure of Ni-Ti endodontic rotary files10851085ENSayedAli MousaviDepartment of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran. sayedali_mousavi@yahoo.comVidaKargar-DehnaviSayedAmir Mousavi20120821Background: Nickel-titanium (Ni-Ti) rotary instrument files are important devices in Endodonticsin root canal preparation. Ni-Ti file breakage is a critical and problematic issue and irrigationtechniques were applied to decrease risk of file failure root. The aim of the present study wasto compare the temperature gradient change of different irrigation solutions with Ni-Ti rotaryinstrument system during root canal preparation and also to define their effects on the file failure.Materials and Methods: A novel computerized instrumentation was utilized and thirty standard(ProFile #25/.04) files were divided into three groups and subjected to a filing in the root canal test.Changes in temperature on teeth under constant instrumental conditions with custom-designedcomputerized experimental apparatus were measured by using a temperature sensor bonded tothe apical hole. A rotary instrument for canal preparation in three series of solution was used andthe changes in temperature after each solution were compared. Finally, the file failure results werementored according to each step of test. Comparisons were performed between group statusclinically by using ANOVA (t) test, once the sample showed up normal and differences of P<0.01were considered significant. All data collected were computerized and analyzed for frequency,distribution, and statistical description.Results: There was a decrease in the temperature of the instruments, which were immersedin 5% NaOCl, when compared with the water group (P<0.01). There was also a decrease in thetemperature of the instruments immersed in water, when compared with the no solution group(P<0.01). Test results showed that sodium hypochlorite, water, or air of root canals does alter theproperties of gradual temperature change and contributes to the failure of the instruments.Conclusion: By immersing the file in 5% NaOCl, the temperature gradient decreased andinstrument failure was reduced.Key Words: File failure, instruments, Ni-Ti, solution, temperature