Cyclic Fatigue of ProFile Vortex and Vortex Blue Nickel-Titanium Files in Single and Double Curvatures

Frederic Duke; Ya Shen; Huimin Zhou; N Dorin Ruse; Zhe-jun Wang; Ahmed Hieawy; Markus Haapasalo

doi:10.1016/j.joen.2015.06.012

Cyclic Fatigue of ProFile Vortex and Vortex Blue Nickel-Titanium Files in Single and Double Curvatures

J Endod. 2015 Oct;41(10):1686-90. doi: 10.1016/j.joen.2015.06.012. Epub 2015 Jul 31.

Authors

Frederic Duke¹, Ya Shen², Huimin Zhou³, N Dorin Ruse¹, Zhe-jun Wang¹, Ahmed Hieawy¹, Markus Haapasalo¹

Affiliations

¹ Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
² Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada. Electronic address: yashen@dentistry.ubc.ca.
³ Center for Biomedical Materials and Engineering, Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin, China.

PMID: 26234542
DOI: 10.1016/j.joen.2015.06.012

Abstract

Introduction: The aims of this study were to determine the flexibility of ProFile Vortex (VX) and Vortex Blue (VB) files (Dentsply Tulsa Dental Specialties, Tulsa, OK) and then to evaluate and compare their fatigue resistance in artificial single curvature and 2 different artificial double curvature canals.

Methods: Flexibility of the files (size 25/.04) in bending was assessed according to ISO 3630-1. Both files were subjected to fatigue tests inside artificial canals with a single curvature (group 1: 60° curvature, 5-mm radius) and with 2 different double curvatures (group 2: first [coronal] curve of 60° curvature and 5-mm radius and the second one [apical] of 30° curvature and 2-mm radius and group 3: first curve of 60° curvature and 5-mm radius and the second one of 60° curvature and 2-mm radius). The number of cycles to fracture (NCF) was recorded, and the fracture surface of all fragments was examined with a scanning electron microscope.

Results: The bending load was significantly lower for VB files than VX files (P < .05), and the 2 types of files followed different trajectories in identical canals. In group 1, the 2 files had significantly higher NCF than in groups 2 and 3 (P < .05). Both files had significantly higher NCF in group 2 than in group 3 (P < .05). In group 1, VB files had fatigue resistance superior to VX files (P < .05), whereas in groups 2 and 3 their fatigue resistance was not statistically different from each other. The crack initiation of a vast majority of files that fractured in double curvature canals (groups 2 and 3) was localized on either 1 of 2 of the 3 cutting edges.

Conclusions: Double curvature canals represent a much more stressful and challenging anatomy than single curvature canals, and, in them, fatigue resistance may be affected by the degrees and the radii of curvatures as well as by the bending properties of the files.

Keywords: Bending property; ProFile Vortex; Vortex Blue; double curvature; fatigue resistance; nickel-titanium files.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Dental Alloys*
Dental Pulp Cavity / anatomy & histology*
Dental Stress Analysis
Equipment Failure
Humans
Nickel*
Root Canal Preparation / instrumentation*
Titanium*

Substances

Dental Alloys
titanium nickelide
Nickel
Titanium