Download - NiTi Briefly

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    Introduction to NiTi The navy worked with NiTi alloy in the

    1950s and 1960s

    They were looking for a non-magnetic,

    waterproof, and salt resistant material

    Initial tests found NiTi to be superelastic

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    NiTi particularly exhibits superelastic

    behavior between 10oC125oC

    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

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    Orthodontics began using NiTi in the late


    NiTi was also useful in wiring fractures in

    orthopedics and oral surgery

    Initial work proved NiTi resisted corrosionin the body and was extremely


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    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 greaterresistance to torsion fractures

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    By 1991 Quality Dental (Johnson City,

    TN), developed a process for grinding NiTialloy 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% morestress than conventional stainless steel

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    University of South Carolina conducted astudy in 1992 with their pre-doctoral


    Fewer cases of broken instruments,

    perforations, and ledges occurred in thegroup using NiTi hand files

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    University of Tennessee conducted a similarstudy in 1993 with their pre-doctoralstudents

    Students using NiTi hand files had

    significantly higher grades, instrumentedthe canals significantly faster, and hadoverall superior results

    NiTi files seemed to work more efficientlyin a reaming motion rather than a filingmotion

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    Table 1: This table illustrates the procedural errors

    made by the students during their proficiency exam

    with the two sets of files. (* Statistically significant)

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    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

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    The first file design, U-File design, which

    continues to be offered today as the Profile,

    GT and LightSpeed, for sizes #15 through


    The second file design, the Sensor File, was

    used in sizes #40-#60 and incorporated twosets of flutes having different helical angles

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    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

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    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

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    In 1993 the University of Tennesseeconducted a study comparing hand stainlesssteel, hand NiTi files, and the NiTiMaticpreparation system with NiTi rotary files

    They found the rotary files to have achieved

    the same shaping goals in about half thetime of the other two groups:

    Rotary 173 s Hand stainless 328 s

    Hand NiTi 351 s

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    The NiTi rotary was found to have maintainedthe apical shape better, indicating fewer ziptype procedural errors

    Amount of material removed at the workinglength:

    Rotary 0.017 mm

    Hand NiTi 0.023 mm

    Hand stainless steel 0.139 mm

    They also found the canal width of the innerwall to be closer to the original width and

    more centered with the rotary group

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    This illustrates the increase in canal width on the

    inside of the curve at the point of curvature.