A Critical Analysis of Frequency and Temperature Effect on the Fatigue Life of Rotary Endodontic Instrument
Date Issued
2009
Date
2009
Author(s)
Liu, Chau-Yuan
Abstract
NiTi rotary instruments are liable to accidental fatigue failure endodontic treatment. Some proposed that the fatigue life of these rotary instruments may be improved by using a lower rotational speed during operation. However, other studies found no correlation between rotational speed and fatigue life. Temperature rise of the instrument under use was overlooked in these studies. In the current work, we investigated the effects of rotational speed as well as temperature. It was found that temperature has a large impact on the fatigue properties of the NiTi instrument. Such effect was related to the phase transformation that took place in the material. Different rotational speeds probably brought about different temperature rises, which in turn affected the fatigue life. The clinical implication is that instrument life and reliability may be greatly improved if its temperature can be kept below a certain level. his study also investigated the effect cryogenic treatment on the fatigue properties of NiTi endodontic rotary instrument. It was found that cryogenic treatment offers 10% improvement in fatigue life. Fatigue life may be greatly enhanced if we can use this technology and control the operation temperature.
Subjects
NiTi endodontic rotary instrument
Fatigue fracture
Temperature effect
Frequency effect
Cryogenic
Martensite
Austenite
Type
thesis
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