Elsevier

Journal of Endodontics

Volume 40, Issue 8, August 2014, Pages 1190-1193
Journal of Endodontics

Basic Research
Evaluation of the Resistance to Cyclic Fatigue among ProTaper Next, ProTaper Universal, and Vortex Blue Rotary Instruments

https://doi.org/10.1016/j.joen.2013.12.033Get rights and content

Abstract

Introduction

The purpose of this study was to compare the fracture resistance to cyclic fatigue of ProTaper Next (PTN; Dentsply Tulsa Dental Specialties, Tulsa, OK), ProTaper Universal (PTU, Dentsply Tulsa Dental Specialties), and Vortex Blue (VB, Dentsply Tulsa Dental Specialties) rotary instruments.

Methods

Twenty instruments each of PTN X1–X5, PTU S1–F5, and VB 20/04–50/04 were rotated until fracture in a simulated canal of 90° and a 5-mm radius using a custom-made testing platform. The number of cycles to fracture (NCF) was calculated. Weibull analysis was used to predict the maximum number of cycles when 99% of the instrument samples survive.

Results

VB 20/04–30/04 had significantly higher NCF than PTU S1–F5 and PTN X1–X5. VB 35/04–45/04 had significantly higher NCF than PTU S2–F5 and PTN X2–X5. PTN X1 had higher NCF than PTU S1–F5. PTN X2 had higher NCF than PTU F2–F5. The Weibull distribution predicted the highest number of cycles at which 99% of instruments survive to be 766 cycles for VB 25/04 and the lowest to be 50 cycles for PTU F2.

Conclusions

Under the limitations of this study, VB 20/04–45/04 were more resistant to cyclic fatigue than PTN X2–X5 and PTU S2–F5. PTN X1 and X2 were more resistant to cyclic fatigue than PTU F2–F5. The Weibull distribution appears to be a feasible and potentially clinically relevant model to predict resistance to cyclic fatigue.

Section snippets

Materials and Methods

PTN consists of a series of 5 instruments called X1, X2, X3, X4, and X5. PTU exists as a series of instruments that are denoted as SX, S1, S2 F1, F2, F3, F4, and F5. The SX instrument was not examined in this study. VB instruments are available in 0.04 and 0.06 tapers. A taper of 0.04 was examined in this study because the manufacturer recommended 0.04 taper instruments in moderate to severe curvatures when instrumenting past the midroot. The following tip sizes for VB were examined: 20, 25,

Results

The mean NCFs and standard deviations for PTN, PTU, and VB are presented in Table 1. One-way analysis of variance and Tukey post hoc tests showed that PTN X1 had significantly higher NCF than PTN X2–X5, PTU S1–F5, and VB 50/04. PTN X1 had significantly lower NCF than VB 20/04–30/04. PTN X2 had significantly higher NCF than PTN X3, PTN X5, and PTU F2–F5. PTN X2 had significantly lower NCF than PTU S1 and VB 20/04–45/04. PTN X3–X5 each had significantly lower NCF than PTU S1–F1 and VB

Discussion

This study is the first to compare cyclic fatigue resistance of PTN and VB using a well-established cyclic fatigue model (1). When comparing PTN and PTU, PTN X2 was significantly more fatigue resistant than PTU F2–F5, but PTN X3 and PTN X4 were not more fatigue resistant than PTU F2–F5. The cutting envelopes at the tips of PTN X2 and PTU F2 are 0.25 mm. If a clinician plans to finish apical instrumentation at a 0.25-mm size, then one may consider finishing with a PTN X2 if fracture resistance

Conclusions

Under the limitations of this study, specifically the fact that only one defined canal geometry was simulated, instruments from VB 20/04–30/04 were more resistant to cyclic fatigue than PTU S1–F5 and PTN X1–X5. VB 35/04–45/04 were more resistant to cyclic fatigue than PTU S2–F5 and PTN X2–X5. PTN X1 was more resistant to cyclic fatigue than PTU S1–F5. PTN X2 was more resistant to cyclic fatigue than PTU F2–F5. The Weibull distribution may be a feasible model to study NiTi rotary instrument

Acknowledgments

Dr Peters serves as a consultant to Dentsply Maillefer, Ballaigues, Switzerland.

The authors deny any conflicts of interest related to this study.

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