Basic research—technology| Volume 33, ISSUE 12, P1477-1480, December 2007

Influence of Previous Angular Deformation on Flexural Fatigue Resistance of K3 Nickel–Titanium Rotary Instruments

Published:October 16, 2007DOI:


      Several studies have evaluated the influence of torsion and bending loads on the mechanical resistance of nickel-titanium instruments. The aim of the present study was to analyze the influence of previous angular deformation on K3 files resistance to flexural fatigue. New files and files previously submitted to different angular deformation were tested for flexural fatigue, and the number of cycles to fracture was compared. The results indicated that as the angular deformation increases, the number of cycles attained under flexural fatigue condition decreases. A reduction of fatigue resistance was registered even when a significant plastic deformation was not imposed. From the obtained results, it may be suggested that the sequential loading, including torsion and flexural fatigue, can be responsible for instrument separation during clinical practice. Successive torsion overloads, occurring together with flexural fatigue, reduce the mechanical resistance of nickel-titanium files.

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        • Sotokawa T.
        An analysis of clinical breakage of root canal instruments.
        J Endod. 1988; 14: 75-82
        • Ankrum M.T.
        • Hartwell G.R.
        • Truitt J.E.
        K3 Endo, ProTaper, and ProFile systems: breakage and distortion in severely curved roots of molars.
        J Endod. 2004; 30: 234-237
        • Alapati S.B.
        • Brantley W.A.
        • Svec T.A.
        • Powers J.M.
        • Nusstein J.M.
        • Daehn G.S.
        SEM observations of nickel-titanium rotary endodontic instruments that fractured during clinical use.
        J Endod. 2005; 31: 40-43
        • Yared G.M.
        • Bou Dagher F.E.
        • Machtou P.
        Cyclic fatigue of Profile rotary instruments after simulated clinical use.
        Int Endod J. 1999; 32: 115-119
        • Yared G.M.
        • Bou Dagher F.E.
        • Machtou P.
        Cyclic fatigue of ProFile rotary instruments after clinical use.
        Int Endod J. 2000; 33: 204-207
        • Gambarini G.
        Cyclic fatigue of nickel-titanium rotary instruments after clinical use with low- and high-torque endodontic motors.
        J Endod. 2001; 27: 772-774
        • Yared G.
        • Kulkarni G.K.
        • Ghossayn F.
        An in vitro study of the torsional properties of new and used K3 instruments.
        Int Endod J. 2003; 36: 764-769
        • Booth J.R.
        • Scheetz J.P.
        • Lemons J.E.
        • Eleazer P.D.
        A comparison of torque required to fracture three different nickel-titanium rotary instruments around curves of the same angle but of different radius when bound at the tip.
        J Endod. 2003; 29: 55-57
        • Ullmann C.J.
        • Peters O.A.
        Effect of cyclic fatigue on static fracture loads in ProTaper nickel-titanium rotary instruments.
        J Endod. 2005; 31: 183-186
        • Barbosa F.O.G.
        • Gomes J.A.C.P.
        • Araújo M.C.P.
        Influence of sodium hypochlorite on mechanical properties of K3 nickel-titanium rotary instruments.
        J Endod. 2007; 33: 982-985
      1. Barbosa FOG, Gomes JACP, Araújo MCP. A study on the fracture mechanism caused by fatigue of endodontic NiTi rotary files. Proceedings of the 4th Latin American Congress of Artificial Organs and Biomaterials; 2006 Aug 8-11; Caxambu, Brazil.

        • Yared G.M.
        • Bou Dagher F.E.
        • Machtou P.
        Influence of rotational speed, torque and operator’s proficiency on ProFile failures.
        Int Endod J. 2001; 34: 47-53
        • Sattapan B.
        • Nervo G.J.
        • Palamara J.E.A.
        • Messer H.H.
        Defects in rotary nickel-titanium files after clinical use.
        J Endod. 2000; 26: 161-165
        • Walia H.
        • Brantley W.A.
        • Gerstein H.
        An initial investigation of the bending and torsional properties of NiTinol root canal files.
        J Endod. 1988; 14: 346-351
        • Pruett J.P.
        • Clement D.J.
        • Carnes D.L.
        Cyclic fatigue testing of nickel-titanium endodontic instruments.
        J Endod. 1997; 23: 77-85
        • Cheung G.S.P.
        • Peng B.
        • Bian Z.
        • Shen Y.
        • Darvell B.W.
        Defects in ProTaper S1 instruments after clinical use: fractographic examination.
        Int Endod J. 2005; 38: 802-809
        • Yao J.H.
        • Schwartz S.A.
        • Beeson T.J.
        Cyclic fatigue of three types of rotary nickel-titanium files in a dynamic model.
        J Endod. 2006; 32: 55-57