title: Cyclic fatigue resistance of newly manufactured rotary nickel titanium instruments used in different rotational directions.
abstract: The aim of this study was to investigate whether cyclic fatigue resistance is increased for nickel titanium instruments manufactured with improved heating processes in clockwise or counterclockwise continuous rotation. The instruments compared were produced either using the R-phase heat treatment (K3XF; SybronEndo, Orange, CA, USA) or the M-wire alloy (ProFile Vortex; DENTSPLY Tulsa Dental Specialties, Tulsa, OK, USA). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments in curved artificial canals. Results indicated no significant difference in resistance to cyclic fatigue when rotary nickel titanium instruments are used in clockwise or counterclockwise continuous rotation. In both directions of rotation, size 04-25 K3XF showed a significant increase (P < 0.05) in the mean number of cycles to failure when compared with size 04-25 ProFile Vortex.
authors.affiliation: Department of Endodontics, La Sapienze University, Rome, Italy Department of Endodontics, Saint Joseph University, Beirut, Lebanon.
authors.forename: Gianlucca
authors.initials: G
authors.lastname: Gambarini
authors.forename: Richard
authors.initials: R
authors.lastname: Gergi
authors.forename: Nicola Maria
authors.initials: NM
authors.lastname: Grande
authors.forename: Nada
authors.initials: N
authors.lastname: Osta
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.forename: Luca
authors.initials: L
authors.lastname: Testarelli
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D004867:Equipment Design; D004868:Equipment Failure; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008669:Metallurgy; D008953:Models, Anatomic; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: clockwise rotation; counterclockwise rotation; cyclic fatigue; heat treatment