Effect of Autoclave Sterilization on the Cyclic Fatigue Resistance of Dentsply Protaper Next, Mani Jizai, and Twisted Nickel Titanium Endodontic Rotary Files: An In Vitro Study

AbstractIntroduction: Using nickel titanium (NiTi) rotational endodontic files increased the predictability of chemomechanical cleaning and shaping; however, instrument separation is a possibility and has been mentioned as a complication in the endodontic literature. Cyclic fatigue occurs as a result of repeated bending of the instruments in curved canals that lead to deformation and stress within the instruments, which end up with fracture due to complete tension compression cycles. Sterilization of NiTi files must be ensured before clinical use, with the exception of those that are presterilized. In this study we are comparing the cyclic fatigue resistance of Dentsply Protaper Next rotary files, Mani Jizai NiTi rotary files, and Sybron Endo Twisted rotary files, in a single curved simulated canal before and after autoclave sterilization.Aim: This study aims to measure and compare the cyclic fatigue resistance of Dentsply Protaper Next rotary files, Mani Jizai rotary files, and Sybron Endo Twisted rotary files in a simulated canal before and after autoclave sterilization.Materials and Method: 66 NiTi rotary files of the same size, i.e., having a tip diameter of 0.25 mm and constant taper 0.06 were used in this study. The files were distributed into 3 groups, each group having 22 files. Then each group was subdivided into two, sterilized and nonsterilized, subgroups having 11 files each. The files were selected on the basis of their metallurgical properties. The files were distributed as Group A: Dentsply Protaper Next; Group B: Mani Jizai; and Group C: Sybron Endo Twisted rotary files. The files were tested using a stainless steel plate. The number of cycles to fracture was calculated.Results: It was observed that increased resistance to cyclic fatigue was seen among nonsterilized files as compared to the sterilized files. Mani Jizai files showed significantly higher fracture resistance than the other files used i.e. Dentsply Protaper Next and Sybron Endo Twisted files.Conclusion: The study provides valuable insights into the selection of NiTi files, their metallurgical properties, and importance of sterilization. As the effect of clinical use was not evaluated in this study, further clinical investigations should be performed.