The Effect of Different Solvents for Gutta-Percha Removal on Cyclic Fatigue Resistance of Nickel-Titanium Retreatment File
Objectives: To evaluate the cyclic fatigue resistance of XP-Endo® Finisher R after immersion in various types of gutta-percha solvent.
Methods: A total of 48 new XP-Endo® Finisher R rotary files, 31 mm in length, were used in this study. These files were equally divided into four groups: the control group (not immersed in gutta-percha solvent) and three experimental groups (immersed in chloroform, eucalyptus oil and GuttaClear). The 16 mm working part of each file was exposed to solvents for 5 minutes. Then the cyclic fatigue testing was performed using a stainless steel artificial canal with a 0.5 mm inner diameter, a curvature angle of 60 degrees and a curvature radius of 5 mm. The time to fracture in seconds was recorded and then the number of cycles to fracture (NCF) was calculated. The length of each fracture fragment was also measured. Two fractured instruments from each group were randomly selected to examine the fracture surface under a scanning electron microscope. Data was analyzed by analysis of variance (ANOVA) and Bonferroni tests (p=0.05).
Results: There were no significant differences between the groups. However, the instruments immersed in eucalyptus oil showed the highest cyclic fatigue resistance followed by chloroform, control group and GuttaClear.
Conclusions: The immersion in different gutta-percha solvents had no effect on the cyclic fatigue resistance of XP-Endo® Finisher R retreatment files.
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