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Introduction to NiTi

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 10 o C – 125 o C

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Introduction to NiTi

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  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. Table 1: This table illustrates the procedural errors made by the students during their proficiency exam with the two sets of files. (* Statistically significant)

  9. 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 uniquely for continuous 360o rotation

  10. The first file design, U-File design, which continues to be offered today as the Profile, GT and LightSpeed, for sizes #15 through #35 • The second file design, the Sensor File, was used in sizes #40-#60 and incorporated two sets of flutes having different helical angles

  11. Oregon Health Sciences Universitycompared four instrumentation techniques • 1) Step-back preparation with K-files • 2) Crown-down preparation with K-files • 3) Sonic instrumentation with Shaper-Sonic files • 4) NiTiMatic preparation system with NiTi rotary files

  12. Incidence of zipping, ledging, and elbow formation was found to be the lowest with the use of the NiTiMatic preparation system with NiTi rotary files

  13. In 1993 the University of Tennessee conducted a study comparing hand stainless steel, hand NiTi files, and the NiTiMatic preparation system with NiTi rotary files • They found the rotary files to have achieved the same shaping goals in about half the time of the other two groups: • Rotary 173 s • Hand stainless 328 s • Hand NiTi 351 s

  14. The NiTi rotary was found to have maintained the apical shape better, indicating fewer zip type procedural errors • Amount of material removed at the working length: • Rotary 0.017 mm • Hand NiTi 0.023 mm • Hand stainless steel 0.139 mm • They also found the canal width of the inner wall to be closer to the original width and more centered with the rotary group

  15. This illustrates the increase in canal width on the inside of the curve at the point of curvature.

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