Influence of Metallurgy and Transformation Temperatures on the Dynamic Cyclic Fatigue Resistance of NiTi Rotary Instruments

  • Manar M. Galal et al.
Keywords: Nickel–titanium instruments, cyclic fatigue, metallurgy, thermomechanical treatment, transformation temperature, reciprocation, dynamic testing.

Abstract

Background: New Nickel–titanium rotary instruments perform safe and fast root canal preparation. However, durability is not guaranteed, as NiTi instruments are prone to cyclic fatigue fracture. Interestingly, both metallurgy and kinematic motion have significant impact on the instruments fatigue resistance.

Aim: The aim of the conducted study was to assess and compare the dynamic cyclic fatigue resistance of three Rotary endodontic instruments made of nickel-titanium (NiTi), all with similar tip size and taper (25/.06) but with different specific metallurgical features (HyFlex CM, Vortex Blue, and EdgeFile). The files tested under both continuous rotation and reciprocation motions.

Materials and Methods: Sixty new NiTi rotary endodontic instruments with size (size 25/.06) were distributed into three groups: HyFlex CM, Vortex Blue, and EdgeFile X7. The files in each group were subdivided into two groups depending on the movement type: continuous rotation and reciprocation. The instruments were tested using a simulated stainless-steel canal with 60° curvature, 5 mm radius in up-down motion. The time was registered, and the number of cycles to the fracture for each file was measured. Two-way ANOVA and Tukey’s post hoc test were used for analysis of the data.

Results: Variables such as metallurgy and motion significantly affected the resistance to cyclic fatigue. HyFlex CM showed the highest mean NCF in both motions (continuous: 920 ± 110; reciprocation: 1620 ± 180), followed by EdgeFile X7 (continuous: 780 ± 95; reciprocation: 1350 ± 160) and Vortex Blue (continuous: 640 ± 85; reciprocation: 1180 ± 140).
Conclusions: Both the Controlled Memory (CM) alloy and the reciprocation motion enhanced the performance and cyclic fatigue resistance of NiTi files.

Author Biography

Manar M. Galal et al.

Manar M. Galal1*, Amira Galal Ismail1, Yousra Aly1, Ali Abdelnabi1, Eyad A.Elbattawy2
1Associate Researcher Professor, Restorative and Dental Materials Department, Oral and Dental Research Institute, National Research Centre, Giza, Dokki, 12622, Egypt.

2 Researcher, Restorative and Dental Materials Department, Oral and Dental Research Institute, National Research Centre, Giza, Dokki, 12622, Egypt.
*Corresponding author: Manar M. Galal
email:
manargalal@windowslive.com

Published
2024-02-04
Issue
Volume 2024
Section
Regular Issue

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