CM Wire Endodontic Files Cyclic Fatigue after Irrigant’s Immersion

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Aim: Cyclic fatigue and scanning electron microscope analysis of a new preheated machined CM wire

endodontic files after immersion for 5 and 10 minutes in irrigants.

Materials and Method: Twenty four size 20 Mpro files were used in this study divided into four groups according to irrigant of 6 files each; saline, chitosan 0.3%, chitosan 0.5% and ethylene diamine tetra acetic acid (EDTA) 17%. Files were immersed in irrigant for 5 or 10 minutes. Cyclic fatigue tests were performed using a static cyclic fatigue testing device. Parameters reported were time to fracture, number of cycles to failure and mean length of unfractured segments. The fractured segments were scanned using a scanning electron microscope to determine the crack initiation site and number of crack origins.

Results: A statistically significant difference existed in mean time to fracture between the different irrigants. At 5 mins immersion time for time of fracture and number of cycles to failure with Chitosan 0.3 group showing the highest mean. At 10 mins immersion time, there was no statistically significant difference but existed only in mean time to fracture between the two immersion times within Chitosan 0.3 and EDTA groups. There was no statistically significant difference in mean length of fractured segments between all groups at 5 mins immersion time but only existed. At 10 mins immersion time within EDTA group. Scanning electron microscope photomicrographs showed that 100% of samples of group 2 chitosan 0.3 showed one site of crack origin.

Conclusion: Chitosan 0.3% had the least destructive effect on the files.