in an advertisement film from FKG for new files (XP-endo finisher), it is shown that the nickel-titanium file bent when it heated ( in body temperature). It is Ok and we all know that shape memory effect active with warming but in that clip (min 4) the bent file becomes straight by cooling!!!
how it happens??
the film link is in 1st comment.
The file is supposed to do that but no harm because the file is out of the canal.
Dear Oscar R. Bolanos thanks for your attention.
unfortunately I do not understand what you mean. Is it possible to explain a little more?
i will try to help but could you please rephrase your question?? I am sorry about my previous answer.
dear Oscar R. Bolanos
In that film, it was shown that XP-endo finisher files after cleaning the first canal and before insert the second canal become straight (file not canal) again by cooling. I want to know how this straightening happened?
Based on my knowledge shape memory effect on heating not in cooling ...
Reversible deformation in nickel-titanium alloys is generally produced by cooling the material from the austenitic phase. Two-way shape memory effects are also possible in which physical deformation of the twinned state is not required. NiTi alloys change from austenite to martensite upon cooling; in the metallurgy, Mf is the temperature at which the transition to martensite completes upon cooling. Accordingly, during heating As and Af are the temperatures at which the transformation from martensite to austenite starts and finishes. Repeated use of the shape-memory effect may lead to a shift of the characteristic transformation temperatures (this effect is known as functional fatigue, as it is closely related with a change of microstructural and functional properties of the material).
Reversible deformation means the forces are no longer applied, the object returns to its original shape .
Dear Ashish Thakur
Ni Ti dental instruments must to autoclaving between application in different patients. This thermal cycles reduce bending fatigue resistance of them. functional fatigue related with this thermal fatigue ? I mean dose mechanical performance of Ni Ti changes during its standard useful life?
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