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Fractographic 분석을 통한 HEROShaper 니켈티타늄 전동 파일의 피로파절에 미치는 표면결함의 역할

Other Titles
 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  ;  Kee-Yeon Kum  ;  Myoung-Whai Kang 
 Journal of Korean Academy of Operative Dentistry (대한치과보존학회지), Vol.32(2) : 130-137, 2007 
Journal Title
Journal of Korean Academy of Operative Dentistry(대한치과보존학회지)
Issue Date
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 flies 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. Croup 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.
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2. College of Dentistry (치과대학) > Dept. of Conservative Dentistry (보존과학교실) > 1. Journal Papers
Yonsei Authors
Kum, Kee Yeon(금기연)
Kim, Eui Seong(김의성) ORCID logo https://orcid.org/0000-0003-2126-4761
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