[Ti-Ni shape memory alloy for dental use. Trial production of prefabricated straight-slit type posts by electric discharge machining].
The possibility of dental application of Ti-Ni shape memory alloys was examined. To determine whether this material which is difficult to be machined could be processed by the electric discharge machining method (E.D.M.), the E.D.M. characteristics of this material were investigated. Trial straight-slit type posts were made by this material under an appropriate electric condition. The term of yield strength, retention force after cementing, and pressure of post when into a root canal filled unset cement were investigated. Ti-Ni shape memory alloy could be processed without a loss of shape memory effect by E.D.M. Hardenning layer in the machined surface was observed by both Ram-type and Wire-type E.D.M., but a thinner hardening layer was observed by the latter method. The retention force after cementing of the trial straight-slit type post were the same or stronger than those of posts on the market. Especially, the dependence for the post's length on this strength was not strong in the trial posts. The pressure produced by inserting the trial post into the root canal filled with unset cement was very low compared with those of post on the market. The trial straight-slit type posts made of Ti-Ni shape memory alloy may be useful for dental application.
Hasegawa
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D003442:Crowns; D003722:Dental Alloys; D004867:Equipment Design; D009532:Nickel; D011176:Post and Core Technique; D014025:Titanium
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium