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2011 Fiscal Year Final Research Report

Change of mechanical properties of Ni-Ti rotary instruments through heat treatment

Research Project

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Project/Area Number 22791824
Research Category

Grant-in-Aid for Young Scientists (B)

Allocation TypeSingle-year Grants
Research Field Conservative dentistry
Research InstitutionTokyo Medical and Dental University

Principal Investigator

YAHATA Yoshio  東京医科歯科大学, 歯学部附属病院, 医員 (30549944)

Project Period (FY) 2010 – 2011
Keywordsニッケルチタンファイル / 熱処理 / 機械的特性
Research Abstract

It is known that the mechanical behavior of Ni-Ti rotary instruments is strongly affected by heat treatment. The aim of this study was to investigate the effect of heat treatment on bending properties, shaping abilities and fatigue properties of Ni-Ti rotary instruments.
Raw Ni. Ti files were heat-treated for 30 minutes at 400(group 400), 450(group 450) and 500(group 500) degrees centigrade. Non heat-treated specimens were used as control. A cantilever-bending test was used to evaluate changes in specimen flexibility both elastic and superelastic deformation range caused by heat treatment. Curved canal models were prepared. Deformed and fractured instruments during preparation were recorded. Pre-and post operative images were superimposed. The amounts of resin removed from both the inner and outer sides of the curvature in the apical 6 mm were determined. The rotational bending test was performed at a rate of 250 rpm until fracture. At 2 mm from the tip, each specimen was deflected horizontally to 1. 0 or 1. 5 mm. All specimens were tested under each deflection. The number of cycles until fracture(NCF) was counted.
In the cantilever-bending test, load values of the control group and group 500 were higher than those of groups 400 and 450 at the elastic range(P<0. 05). At the superelastic range, the bending load of the control group was the highest amongst all groups(p<0. 05). Regarding shaping ability, in the control group, root canals at the apex were transported more to the outer side of the curvature compared with those of all heat-treated groups(p<0. 05). In the rotational bending test, as compared to the control group, Groups 450 and 500 showed a higher NCF under 1. 0 and 1. 5 mm deflection, whereas Group 400 showed a higher NCF only under 1. 5 mm deflection(p<0. 05).
In conclusion, heat treatment of files might improve their flexibility and fatigue life, making them more effective for preparation of cured canals.

  • Research Products

    (9 results)

All 2012 2011 Other

All Journal Article (3 results) Presentation (3 results) Book (3 results)

  • [Journal Article] Nano-indentation of NiTi Endodontic Instruments after Cyclic Fatigue2012

    • Author(s)
      Jamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda H
    • Journal Title

      International Endodontic Journal

      Volume: 45

  • [Journal Article] Heat treatment of nickel-titanium rotary endodontic instruments : effects on bending properties and shaping bilities2011

    • Author(s)
      Ebihara A, Yahata Y, Miyara K, Nakano K, Hayashi Y, Suda H
    • Journal Title

      International Endodontic Journal

      Volume: 44 Pages: 843-849

  • [Journal Article] 複雑な根管を呈する下顎小臼歯の歯内治療-歯科用実体顕微鏡とコーンビームCTの有用性-

    • Author(s)
      八幡祥生, 山内隆守, 海老原新, 須田英明
    • Journal Title

      日本歯内療法学会雑誌

      Volume: (in press)

  • [Presentation] Change of fatigue property of Ni-Ti rotary instruments through heat treatment2011

    • Author(s)
      Yahata Y, Miyara K, Jamleh A. O, Hayashi Y, Ebihara A, Suda H
    • Organizer
      American Association of Endodontists 2011 annual session
    • Place of Presentation
      San Antonio Texas, USA
    • Year and Date
      20110000
  • [Presentation] Nanoindentation of NiTi Endodontic Instruments after Cyclic Fatigue2011

    • Author(s)
      Jamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda H
    • Organizer
      The 136th Scientific meeting of Korean Academy of Conservative Dentistry and 13th Scientific joint meeting between JSCD and KACD
    • Place of Presentation
      Seoul, Korea
    • Year and Date
      20110000
  • [Presentation] 新型ニッケルチタンファイルProFile Vortexの曲げ特性および相変態挙動2011

    • Author(s)
      宮良香菜,八幡祥生,海老原新,塙隆夫,須田英明
    • Organizer
      第134回日本歯科保存学会春季学術大会
    • Place of Presentation
      千葉
    • Year and Date
      20110000
  • [Book] 東京医科歯科大学生体材料工学研究所60年史,基礎研究と臨床の懸け橋として2011

    • Author(s)
      八幡祥生,須田英明
    • Total Pages
      28
    • Publisher
      医科歯科BLOOM
  • [Book] Editorial ; ROOTS internationalmagazine of endodontology 72011

    • Author(s)
      Yahata Y
    • Total Pages
      103
    • Publisher
      OemusMedia AG
  • [Book] Editorial ; Dental Tribune AsiaPacific Edition 92011

    • Author(s)
      Yahata Y
    • Total Pages
      4
    • Publisher
      Dental Tribune AsiaPacific Ltd.

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Published: 2013-07-31   Modified: 2015-12-16  

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