NickelTitanium Rotary Files in Endodontics （在牙髓学NickelTitanium扶轮文件）.pptVIP

Introduction to NiTi The navy worked with NiTi alloy in the 1950’s and 1960’s They were looking for a non-magnetic, waterproof, and salt resistant material Initial tests found NiTi to be superelastic NiTi particularly exhibits superelastic behavior between 10oC – 125oC Other alloys with superelastic properties are the alloys of copper-zinc, copper-aluminum, or titanium-niobium Ideal temperature range in endodontics is 23oC to 36oC, the temperatures found in the composition of 50% Ni and 50% Ti Orthodontics began using NiTi in the late 1970’s NiTi was also useful in wiring fractures in orthopedics and oral surgery Initial work proved NiTi resisted corrosion in the body and was extremely biocompatible The First Use of NiTi in Endodontic Hand Files Walia, Brantley, and Gerstein conducted the first reported investigation of the NiTi alloy in endodontics in 1988 Testing concluded that the NiTi had two to three times the elastic flexibility and greater resistance to torsion fractures By 1991 Quality Dental (Johnson City, TN), developed a process for grinding NiTi alloy files for NiTi Co. (Chattanooga, TN) It was reported to be 500% more flexible than conventional stainless steel and said to be capable of withstanding 1000% more stress than conventional stainless steel University of South Carolina conducted a study in 1992 with their pre-doctoral students Fewer cases of broken instruments, perforations, and ledges occurred in the group using NiTi hand files University of Tennessee conducted a similar study in 1993 with their pre-doctoral students Students using NiTi hand files had significantly higher grades, instrumented the canals significantly faster, and had overall superior results NiTi files seemed to work more efficiently in a reaming motion rather than a filing motion The First Use of NiTi in Endodontic Rotary Files 1991 NiTi Co. had two rotary file designs to make up their file line These two file designs were developed unique