The purpose of this study was to test the number of rotations to fracture of the M-Wire GT® Series X(TM) rotary files compared to the original ProFile® GT® rotary files in a simulated curved canal. Eighty GT® Series X(TM) files of 25mm length were divided into eight groups of ten, one for each of the new GT® Series X(TM) files. Eighty original ProFile® GT® files of 25mm length were divided into eight groups of the same tip and taper sizes consistent with the GT® Series X(TM) file groups. Files were rotated at 300 rpm. While the angle may have slightly changed due to the flexure property of the file, the angle was the same for each file with the same tip and taper. The time to fracture was recorded and rotations to fracture were calculated. The data collected was analyzed using a two-way ANOVA, followed by specific post-hoc contrasts comparing the two brands for each tip and taper combination. The results show the M-Wire GT® Series X(TM) files were significantly more resistant to fracture by cyclic fatigue than the ProFile® GT® rotary instruments for the following tip and taper sizes: 20/.04, 30/.04, 30/.06, 30/.08, and 40/.08. The following tip and taper sizes: 20/.06, 40/.04, and 40/.06 were not statistically significant.

The purpose of this study was to examine the number of rotations to failure of two different rotary file systems, EndoSquence Brassler USA (Savannah, GA) and GT(TM) series X(TM). Files sizes 20,30,40 with 0.04, 0.06 tapers of GT series X and Endo Sequence files size and taper used were 20, 30, 40 with 0.04 and 0.06 taper. Like tip and tapers were compared between systems. All files tested were 25mm in length. Files were allocated into 12 groups of 10 files each, and mounted to a universal testing machine. Each file was rotated at 300 rpms until fractured occurred. The number of rotations to fracture were calculated. A two-way ANOVA indicated that each of the 12 groups were significantly different (p < .0001). The Brand Tip/Taper interaction indicated that the differences between the brands varied by Tip/Taper combination (p < .0001). The tip/taper combination 20/.04, the GT series X file rotated 1.4 times longer than the EndoSequence (p = 0.0027). The tip/taper combination 20/.06, the GT series X file rotated 1.61 times longer than the EndoSequence (p = <.0001). The tip/taper combination 30/.04, the GT series X file rotated 3.67 times longer, than the EndoSequence (p = <.0001). For the tip/taper combination 30/.06, the GT series X file rotated 2.63 times longer than the EndoSequence (p = <.0001). For the tip/taper combination 40/.06, the GT series X file rotated 4.05 times longer than the EndoSequence (p = <.0001). In comparing all these tip and taper combinations GT series X was significantly higher rotations to failure. Comparing tip/taper combination 40/.04, the GT series X file rotated 1.22 times longer, however, this was not significantly different than the Sequence (p = 0.0707). The results suggested that the number of rotations to failure for GT series X files were greater than the EndoSequence file of the same tip and taper combination.

The purpose of this study was to compare the resistance to fracture by the twisting of two nickel titanium (NiTi) rotary file systems. The Profile® GT® (GT) and the GT® Series X(TM) (GTX) files were tested to analyze the maximum torsional strength and the maximum angular deflection at the time of separation of the files. For each system, ten new files were tested at each of the following eight taper/size designations for a total of 160 files: 20/0.04, 20/0.06, 30/0.04, 30/0.06, 30/0.08, 40/0.04, 40/0.06, and 40/0.08. The American National Standards Institute / American Dental Association Specification No. 28 was implemented to evaluate torsional limits for these intruments. Files were mounted in a Maillefer Torsiometre machine, which records maximum torsional strength and angular deflection at separation for each file. A two-way ANOVA revealed significant differences after comparing the size and type of file. The GT files required significantly more torque to separate than the GTX files in all groups tested except the GTX file size 20/0.06, which required significantly more maximum torque than the GT file, with no significant difference between the GT and GTX files for size 30/0.04. The GT files exhibited values for angular deflection at separation that were significantly higher than those for the GTX files at sizes 30/0.04 and 40/0.08 and the GTX files exhibited higher values at size 30/0.08 with no significant difference between the brands at the remaining five file sizes. In summary, the GT files required significantly more torque to fracture and exhibited values for angular deflection at separation that were significantly higher than the GTX files for in 6 of 8 and 2 of 8 file sizes, respectively.