title: Comparison of cyclic fatigue and torsional resistance in reciprocating single-file systems and continuous rotary instrumentation systems.
abstract: As compared with continuous rotary systems, reciprocating motion is believed to increase the fatigue resistance of NiTi instruments. We compared the cyclic fatigue and torsional resistance of reciprocating single-file systems and continuous rotary instrumentation systems in simulated root canals. Eighty instruments from the ProTaper Universal, WaveOne, MTwo, and Reciproc systems (n = 20) were submitted to dynamic bending testing in stainless-steel simulated curved canals. Axial displacement of the simulated canals was performed with half of the instruments (n = 10), with back-and-forth movements in a range of 1.5 mm. Time until fracture was recorded, and the number of cycles until instrument fracture was calculated. Cyclic fatigue resistance was greater for reciprocating systems than for rotary systems (P < 0.05). Instruments from the Reciproc and WaveOne systems significantly differed only when axial displacement occurred (P < 0.05). Instruments of the ProTaper Universal and MTwo systems did not significantly differ (P > 0.05). Cyclic fatigue and torsional resistance were greater for reciprocating systems than for continuous rotary systems, irrespective of axial displacement.
authors.affiliation: Department of Endodontics, Paulista University.
authors.forename: Matheus F
authors.initials: MF
authors.lastname: da Frota
authors.forename: Camila G
authors.initials: CG
authors.lastname: Espir
authors.forename: Fábio L C V
authors.initials: FL
authors.lastname: Berbert
authors.forename: André A F
authors.initials: AA
authors.lastname: Marques
authors.forename: Emílio C
authors.initials: EC
authors.lastname: Sponchiado-Junior
authors.forename: Mario
authors.initials: M
authors.lastname: Tanomaru-Filho
authors.forename: Lucas F R
authors.initials: LF
authors.lastname: Garcia
authors.forename: Idomeo
authors.initials: I
authors.lastname: Bonetti-Filho
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004548:Elasticity; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D018583:Pliability; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D019415:Torque; D054159:Torsion, Mechanical
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium