title: Performance of NiTi endodontic instrument under different temperatures.
abstract: The purpose of this study was to test nickel titanium (NiTi) instrument performance under different surrounding temperatures. Twenty-four superelastic NiTi instruments with a conical shape comprising a 0.30-mm-diameter tip and 0.06 taper were equally divided into 3 groups according to the temperature employed. Using a specially designed cyclic fatigue testing apparatus, each instrument was deflected to give a curvature 10 mm in radius and a 30° angle. This position was kept as the instrument was immersed in a continuous flow of water under a temperature of 10, 37, or 50 °C for 20 s to calculate the deflecting load (DL). In the same position, the instrument was then allowed to rotate at 300 rpm to fracture, and the working time was converted to the number of cycles to fracture (NCF). The statistical significance was set at p = 0.05. The mean DL (in N) and NCF (in cycles) of the groups at 10, 37, and 50 °C were 10.16 ± 1.36 and 135.50 ± 31.48, 13.50 ± 0.92 and 89.20 ± 16.44, and 14.70 ± 1.21 and 65.50 ± 15.90, respectively. The group at 10 °C had significantly the lowest DL that favorably resulted in the highest NCF. Within the limitations of this study, the surrounding temperature influences the cyclic fatigue resistance and DL of the superelastic NiTi instruments. Lower temperatures are found to favorably decrease the DL and extend the lifetime of the superelastic NiTi instrument. Further NiTi instrument failure studies should be performed under simulated body temperature.
authors: Department of Restorative and Prosthetic Sciences, College of Dentistry, National Guard Health Affairs, King Saud bin Abdulaziz University for Health Sciences, Khashm Al An, Riyadh, 22490-11426, Saudi Arabia.
authors: Ahmed
authors: A
authors: Jamleh
authors: Division of Endodontology, Department of Conservative Dentistry, Showa University School of Dentistry, 2-1-1, Kitasenzoku, Ota-ku, Tokyo, 145-8515, Japan.
authors: Yoshio
authors: Y
authors: Yahata
authors: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. a.ebihara.endo@tmd.ac.jp.
authors: Arata
authors: A
authors: Ebihara
authors: Department of Conservative Dentistry, Jordan University of Science and Technology, Ar Ramtha, Irbid, 22110, Jordan.
authors: Amre R
authors: AR
authors: Atmeh
authors: Cariology and Operative Dentistry, King Abdulaziz University, Abdullah Sulayman, Jeddah, 22254, Saudi Arabia.
authors: Turki
authors: T
authors: Bakhsh
authors: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
authors: Hideaki
authors: H
authors: Suda
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003762:Dental Instruments; D004548:Elasticity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Deflecting load; Number of cycles to failure; Superelastic NiTi instrument; Temperature