Application of fiber Bragg grating sensors in monitoring fatigue failure of NiTi rotary endodontic instruments

C. Y. Liu; C. S. Shin

doi:10.1117/12.923219

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12 April 2012 Application of fiber Bragg grating sensors in monitoring fatigue failure of NiTi rotary endodontic instruments

C. Y. Liu, C. S. Shin

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Proceedings Volume 8409, Third International Conference on Smart Materials and Nanotechnology in Engineering; 84091V (2012) https://doi.org/10.1117/12.923219
Event: Third International Conference on Smart Materials and Nanotechnology in Engineering, 2011, Shenzhen, China

Abstract

NiTi endodontic rotary instruments subjected to alternating tension and compression stress in root canals may fracture without prior warning. Once broken, extracting the fractured part from the canal is a difficult job and is annoying to both the patient and the dentist. Warning of an imminent fracture during clinical use will be a great help to avoid medical and legal complications. A monitoring system employing Fiber Bragg Grating (FBG) sensors has been attempted. The reason of using FBG is its small size which is very promising in integrating with the handpiece of the endodontic equipment. When cracking developed in an rotary instrument, we expect the natural vibration frequency of the instrument changes. If we can pick up the stress wave transmitted through the structural components of the rotary instruments, we may be able to detect the occurrence of a crack. In the current work, we found that we can successfully locate the operation period in the time domain by picking up and analyzing the sound wave using FBG. Furthermore, by employing Fast Fourier Transform (FFT) on the signal, we can reveal the energy variation and the frequency shifting phenomenon in specific section of frequency domain. For some characteristic frequencies, it was found that the energy and frequency varied in a well-defined pattern during the period of crack growth. It is hoped that with these information, the fatigue failure of rotary instruments can be closely monitored to avoid/alleviate the occurrence of unexpected fracture during clinical use.

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C. Y. Liu and C. S. Shin "Application of fiber Bragg grating sensors in monitoring fatigue failure of NiTi rotary endodontic instruments", Proc. SPIE 8409, Third International Conference on Smart Materials and Nanotechnology in Engineering, 84091V (12 April 2012); https://doi.org/10.1117/12.923219

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