Fatigue Resistance of a 3-dimensional Conforming Nickel-Titanium Rotary Instrument in Double Curvatures.
BACKGROUND
Fatigue resistance of ProFile, Vortex Blue, and TRUShape files in artificial single curvature and in 2 different artificial double curvature canals was evaluated.


METHODS
Three files (ProFile, Vortex Blue [size 20/.06], and TRUShape [size 20/.06v]) were subjected to fatigue tests in a single curvature (group 1: 60° curvature) and 2 different double curvatures (group 2: 60° and 30° curvatures; group 3: two 60° curvatures). The time to fracture and the total number of cycles to failure were recorded. The fracture surfaces of the fragments were examined with a scanning electron microscope.


RESULTS
All files had significantly higher fatigue resistance in a single curvature canal than in the double curvature canals. In a single curvature group, the time to fracture of TRUShape and ProFile was longer than in Vortex Blue files. In both double curvature groups, TRUShape had the longest time to fracture among all files. The fatigue resistance (the time to fracture and number of cycles to failure) of ProFile and Vortex Blue was lower in group 3 than in group 2 (P < .05). However, there was no significant difference in fatigue resistance of TRUShape in the double curvature groups. The length of the fragment of TRUShape was longer than in Vortex Blue and ProFile files in group 3 (P < .05).


CONCLUSIONS
The fatigue performance of TRUShape is different in double curvature canals, compared with conventional nickel-titanium rotary files. The fatigue resistance of TRUShape was superior to ProFile and Vortex Blue in double curvature canals.
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada.
Ya
Y
Shen
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada.
Ahmed
A
Hieawy
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada; Department of Conservative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-Sen University, Guangzhou, China.
Xiangya
X
Huang
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada.
Zhe-Jun
ZJ
Wang
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada; Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.
Hazuki
H
Maezono
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: markush@dentistry.ubc.ca.
Markus
M
Haapasalo
D000704:Analysis of Variance; D003722:Dental Alloys / Q000737:chemistry*; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D004867:Equipment Design; D004868:Equipment Failure; D015775:Fractures, Stress; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D019415:Torque
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
Double curvatures; ProFile; TRUShape; Vortex Blue; fatigue resistance; nickel-titanium instrument