Effect of 4 Different Irrigation Media on Cyclic Fatigue of 2 Different Files in Double Curved Simulated Canal

Background: Ni Ti mechanical properties is of great importance that give the files its flexibility and grant us a more convenience preparation in curved and double curved canals. Instrument separation during canal preparation is a common incidence, and a cyclic fatigue (metal fatigue) is a common reason. The aim of this study: is to compare the impact of 4 different irritant conditions on the cyclic fatigue of 2 kinds of NiTi instrument: forty One curve rotary files (taper 0.06, 0.25 tip size) (Micro Mega, France), forty Reciproc blue rotary files (taper 0.08, 0.25 tip size) (VDW, Munich, Germany), in a custom made double curved stainless steel artificial canal. Materials and Methods: eighty NiTi files are included in this analysis and divided into four subgroups for each main group A: Sodium hypochlorite 5.25% Group B: chlorhexidine gluconate 2% Group C: Distilled water Group D: without irrigant Each group subdivided into four subgroups each group (n=10) used in double curved canal. A torque-controlled handpiece was operated with all instruments and mounted on surveyor with special tool for standardization and were utilized according manufacturer instruction and exposed to cyclic fatigue testing until instrument fracture happens. The time for fracture was recorded, and then the cycles number was recorded. one-way ANOVA is utilized to analyze the data statistically, among groups. Post hoc tukey test to select the significance of results. Result: For all groups, the best cyclic fatigue resistance was seen with chlorhexidine digluconate (p ≤ 0.05) followed by distilled water then sodium hypochlorite and without irrigant, respectively. The resistance of one curve file to cyclic fatigue is smaller than that of reciproc blue files. conclusion for this study is firstly the best of the 4 irrigant conditions used in this study that showed increased resistance to cyclic fatigue is chlorhexidine gluconate 2% followed by distilled water and then sodium hypochlorite 5.25% and the least one is an empty canal (without irrigant) and the strongest file used in this study is Reciproc blue followed by One curve