Bending Properties of a New Nickel-Titanium Alloy with a Lower Percent by Weight of Nickel

doi:10.1016/j.joen.2011.05.023

Journal of Endodontics

Volume 37, Issue 9, September 2011, Pages 1293-1295

https://doi.org/10.1016/j.joen.2011.05.023 Get rights and content

Abstract

Introduction

The aim of the present study was to evaluate the bending properties of Hyflex instruments, which exhibit a lower percent in weight of nickel (52 Ni %wt) and compare them with other commercially available nickel-titanium (NiTi) rotary instruments.

Methods

Ten instruments with tip size 25, 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for the study: Hyflex, EndoSequence, ProFile, Hero, and Flexmasters. All instruments from each group were tested for stiffness by comparing their bending moment when they attained a 45-degree bend. Experimental procedures strictly followed testing methodology described in ISO 3630-1. All data were recorded and subjected to statistical evaluation by using analysis of variance test. Statistical significance was set at P < .05).

Results

Statistical analysis of the data revealed that Hyflex files were found to be the most flexible instruments, with a significant difference (P < .05) in comparison with the other instruments. Among the other files, a significant difference has been reported for EndoSequence instruments compared with ProFile, Hero, and FlexMaster (P < .05), whereas no significant differences have been reported among those 3 files (P > .05).

Conclusions

Results of the present study have illustrated an increased flexibility of the new NiTi alloy over conventional NiTi alloy, and they highlight the potential of the new manufacturing process.

Section snippets

Materials and Methods

Ten instruments with tip size 25 and 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for the study: (1) Hyflex (Coltene-Whaledent, Allstetten, Switzerland), (2) EndoSequence (Brasseler, Savannah, GA), (3) ProFile (Dentsply-Maillefer, Baillagues, Switzerland), (4) Hero (MicroMega, Besancon, France), and (5) Flexmaster (VDW, Munchen, Germany).

All instruments from each group were tested for stiffness by comparing their bending moment when they attained a

Results

Mean values and standard deviation for each group of instruments are shown in Table 1. The higher the value, the more rigid were the instruments. Statistical analysis of the data revealed that Hyflex files were found to be the most flexible instruments, with a significant difference (P < .05) in comparison with the other instruments. Among the other files, a significant difference was found for EndoSequence instruments compared with ProFile, Hero, and FlexMaster (P < .05), whereas no

Discussion

Thermal treatment of NiTi alloys for endodontic use is a new field of research, and little information is currently available. Thermal treatment of the alloy is known to produce a better arrangement of the crystal structure, thus leading to improved flexibility (superelastic behavior), and also changes in the percentage of phases (a different grain structure) of the alloy, thus leading to improved resistance or plastic behavior. Patented, proprietary processes are highly influenced by

Acknowledgments

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

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Nickel-titanium (NiTi) alloy has been extensively researched in endodontics, particularly in cleaning and shaping the root canal system. Research advances have primarily focused on the design, shape, and geometry of the NiTi files as well as metallurgy and mechanical properties. So far, extensive investigations have been made surrounding surface and thermomechanical treatments, however, limited work has been done in the realm of surface functionalization to augment its performance in endodontics. This review summarizes the unique characteristics, current use, and latest developments in thermomechanically treated NiTi endodontic files. It discusses recent improvements in nano-engineering and the possibility of customizing the NiTi file surface for added functionalization. Whilst clinical translation of this technology has yet to be fully realized, future research direction will lie in the use of nanotechnology.
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Besides this, canal's anatomy, dentin's hardness, and endodontic motor also inevitably generate flexural and torsional stresses on the Ni-Ti files during root canal treatment [112]. To evaluate torsional and flexural strength of Ni-Ti files, researchers have referred to American Dental Association Specification No. 28 [74,102,105,110,113–118] and ISO 3630–1 [102,106,110,118–125], respectively. File kinematics also affect the torque generated during canal treatment.
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Twenty mandibular incisors were selected and divided into two groups instrumented using HyFlex CM (HCM) and ProTaper Universal (PTU) systems. OCT scans were taken immediately after canal instrumentation with file #25, #30 and #40. Each cross-sectional reconstructed image of 1, 2 and 3 mm from the apex was examined, root cracks were scored, and dentin thickness was measured at 12 sites. The risk sites with dentin thickness less than 0.30 mm were recorded.
In HCM group, no cracks were observed after instrumentation with file #30/.06, while in PTU group, root cracks were found in 6 teeth with a total score of 9 after using F3 (#30/.09) (P < 0.05). After file #40, 8 teeth with cracks had a score of 14 in PTU group, while one tooth was observed crack with a score of 1 in HCM group (P < 0.05). The number of risk sites in PTU group was 49 (13.16%), which was significantly more than the 28 (7.78%) in HCM group (P < 0.05) when canals were instrumented with file #30.
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Basic ResearchBending Properties of a New Nickel-Titanium Alloy with a Lower Percent by Weight of Nickel

Abstract

Introduction

Methods

Results

Conclusions

Section snippets

Materials and Methods

Results

Discussion

Acknowledgments

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Alloys Compd

J Alloys Compd

Mater Sci Eng A

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Endod

An overview of nickel-titanium alloys used in dentistry

Int Endod J

The utility of superelasticity in medicine

Biomed Mater Eng

Phase transformation behaviour and bending property of twisted nickel-titanium endodontic instruments

Int Endod J

Mechanical properties of nickel-titanium rotary instruments produced with a new manufacturing technique

Int Endod J

Basic Research
Bending Properties of a New Nickel-Titanium Alloy with a Lower Percent by Weight of Nickel