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2 "HEROShaper"
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The Effect of Surface Defects on the Cyclic Fatigue Fracture of HEROShaper Ni-Ti rotary files in a Dynamic Model: A Fractographic Analysis
Jung-Kyu Lee, Eui-Sung Kim, Myoung-Whai Kang, Kee-Yeon Kum
J Korean Acad Conserv Dent 2007;32(2):130-137.   Published online March 31, 2007
DOI: https://doi.org/10.5395/JKACD.2007.32.2.130
AbstractAbstract PDFPubReaderePub

This in vitro study examined the effect of surface defects on cutting blades on the extent of the cyclic fatigue fracture of HEROShaper Ni-Ti rotary files using fractographic analysis of the fractured surfaces. A total of 45 HEROShaper (MicroMega) Ni-Ti rotary files with a #30/.04 taper were divided into three groups of 15 each. Group 1 contained new HEROShapers without any surface defects. Group 2 contained HEROShapers with manufacturing defects such as metal rollover and machining marks. Group 3 contained HEROShapers that had been clinically used for the canal preparation of 4-6 molars. A fatigue-testing device was designed to allow cyclic tension and compressive stress on the tip of the instrument whilst maintaining similar conditions to those experienced in a clinic. The level of fatigue fracture time was measured using a computer connected the system. Statistical analysis was performed using a Tukey's test. Scanning electron microscopy (SEM) was used for fractographic analysis of the fractured surfaces. The fatigue fracture time between groups 1 and 2, and between groups 1 and 3 was significantly different (p < 0.05) but there was no significant difference between groups 2 and 3 (p > 0.05). A low magnification SEM views show brittle fracture as the main initial failure mode. At higher magnification, the brittle fracture region showed clusters of fatigue striations and a large number of secondary cracks. These fractures typically led to a central region of catastrophic ductile failure. Qualitatively, the ductile fracture region was characterized by the formation of microvoids and dimpling. The fractured surfaces of the HEROShapers in groups 2 and 3 were always associated with pre-existing surface defects. Typically, the fractured surface in the brittle fracture region showed evidence of cleavage (transgranular) facets across the grains, as well as intergranular facets along the grain boundaries. These results show that surface defects on cutting blades of Ni-Ti rotary files might be the preferred sites for the origin of fatigue fracture under experimental conditions. Furthermore, this work demonstrates the utility of fractography in evaluating the failure of Ni-Ti rotary files.

Citations

Citations to this article as recorded by  
  • The Effect of Canal Curvature and Different Manufacturing Processes of Five Different NiTi Rotary Files on Cyclic Fatigue Resistance
    Panupat Phumpatrakom, Awiruth Klaisiri, Sukitti Techapatiphandee, Thippawan Saekow, Panuroot Aguilar
    European Journal of General Dentistry.2024;[Epub]     CrossRef
  • Effect of internal stress on cyclic fatigue failure in .06 taper ProFile
    Hye-Rim Jung, Jin-Woo Kim, Kyung-Mo Cho, Se-Hee Park
    Restorative Dentistry & Endodontics.2012; 37(2): 79.     CrossRef
  • Effect of internal stress on cyclic fatigue failure in K3
    Jun-Young Kim, Jin-Woo Kim, Kyung-Mo Cho, Se-Hee Park
    Restorative Dentistry & Endodontics.2012; 37(2): 74.     CrossRef
  • Stress distribution for NiTi files of triangular based and rectangular based cross-sections using 3-dimensional finite element analysis
    Hyun-Ju Kim, Chan-Joo Lee, Byung-Min Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
    Journal of Korean Academy of Conservative Dentistry.2009; 34(1): 1.     CrossRef
  • Comparative analysis of various corrosive environmental conditions for NiTi rotary files
    Ji-Wan Yum, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
    Journal of Korean Academy of Conservative Dentistry.2008; 33(4): 377.     CrossRef
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Comparison of shaping ability between various hybrid instrumentation methods with ProTaper
Eun-Sook Hong, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
J Korean Acad Conserv Dent 2006;31(1):11-19.   Published online January 31, 2006
DOI: https://doi.org/10.5395/JKACD.2006.31.1.011
AbstractAbstract PDFPubReaderePub

The purpose of this study was to compare and evaluate the shaping abilities of various hybrid instrumentation method using constant tapered file systems with ProTaper® S1 and the difference between experts and inexperienced clinicians in use of NiTi file.

Three hybrid methods used in this study were composed of ProTaper® S1 and K-Flexofile® (group S), ProTaper® S1 and HeroShaper® (group H), and ProTaper® S1 and ProFile® (group P), respectively. The ProTaper®-alone method (group C) was introduced as a control group.

After canal preparation, the lapse of time was recorded. The images of pre- and post-operative canal were scanned and superimposed. Amounts of instrumented canal widths and centering ratio were measured at apical 1, 2 and 3 mm levels and statistical analysis was performed.

In this study, both of the group C and S took more time to prepare canals than other groups. Inexperienced operators required more time for the entire preparation with the groups C and H than the experienced (p < 0.05). And the centering ratio of group P were preferable to ProTaper®-alone method or the hybrid technique using stainless steel files. As such, within experienced operators, group H also showed better results in addition to the group P.

Under these condition, the hybrid methods of each the ProFile® system and HeroShaper® with ProTaper® are recommendable comparative to ProTaper®-alone method. According to the results, the hybrid instrumentation method is a more appropriate method of canal preparation than single file system for narrow or curved canals.

Citations

Citations to this article as recorded by  
  • Mechanical and geometric features of endodontic instruments and its clinical effect
    Hyeon-Cheol Kim
    Journal of Korean Academy of Conservative Dentistry.2011; 36(1): 1.     CrossRef
  • Comparison of Forces Generated During Root Canal Shaping and Residual Stresses of Three Nickel–Titanium Rotary Files by Using a Three-Dimensional Finite-element Analysis
    Hyeon-Cheol Kim, Gary Shun-Pan Cheung, Chan-Joo Lee, Byung-Min Kim, Jeong-Kil Park, Soon-Il Kang
    Journal of Endodontics.2008; 34(6): 743.     CrossRef
  • Comparison of shaping ability between single length technique and crown-down technique using Mtwo rotary file
    Yoo-Kyoung Lim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
    Journal of Korean Academy of Conservative Dentistry.2007; 32(4): 385.     CrossRef
  • Comparison of shaping ability using various Nickel-Titanium rotary files and hybrid technique
    Jung-Won Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
    Journal of Korean Academy of Conservative Dentistry.2007; 32(6): 530.     CrossRef
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  • 4 Crossref
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