title: Application of nondestructive testing in cyclic fatigue evaluation of endodontic Ni-Ti rotary instruments.
abstract: The purpose of this study was to investigate the application of nondestructive testing in cyclic fatigue evaluation of endodontic ProFile nickel-titanium (NiTi) rotary instruments. As-received ProFile instruments were made to rotate freely in sloped metal blocks by a contra-angle handpiece mounted on a testing machine. Rotation was interrupted periodically, and the instrument removed and engaged onto a device to monitor its stiffness by using two strain gauges in four different directions. This monitoring method has the potential to be developed into a convenient, nondestructive turnkey system that allows in situ assessment of the integrity of NiTi instruments in the clinic. Upon fracture, which was indicated by a change in instrument stiffness, the fractured surface would be examined under a scanning electron microscope. Microscopic evaluation indicated a small area of fatigue fracture with a large area of final ductile fracture, whereby the latter was the major cyclic failure mode. Based on the results of this study, we concluded that a potential nondestructive integrity assessment method for NiTi rotary instruments was developed.
authors.affiliation: Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei 10016, Taiwan, ROC.
authors.forename: Uei-Ming
authors.initials: UM
authors.lastname: Li
authors.forename: Chow-Shing
authors.initials: CS
authors.lastname: Shin
authors.forename: Wan-Hong
authors.initials: WH
authors.lastname: Lan
authors.forename: Chun-Pin
authors.initials: CP
authors.lastname: Lin
mesh_terms: D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods*; D019544:Equipment Failure Analysis / Q000379:methods; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D014025:Titanium; D014159:Transducers
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium