title: Comparison of forces generated during root canal shaping and residual stresses of three nickel-titanium rotary files by using a three-dimensional finite-element analysis.
abstract: The study was aimed to compare the stress distribution during simulated root canal shaping and to estimate the residual stress thereafter for some nickel-titanium rotary instruments. Three brands of instruments (ProFile, ProTaper, and ProTaper Universal; Dentsply Maillefer) were scanned with micro-computed tomography to produce a real-size, 3-dimensional model for each. The stresses on the instrument during simulated shaping of a root canal were analyzed numerically by using a 3-dimensional finite-element package, taking into account the nonlinear mechanical behavior of the nickel-titanium material. From the simulation, the original ProTaper design showed the greatest pull in the apical direction and the highest reaction torque from the root canal wall, whereas ProFile showed the least. In ProTaper, stresses were concentrated at the cutting edge, and the residual stress reached a level close to the critical stress for phase transformation of the material. The residual stress was highest in ProTaper followed by ProTaper Universal and ProFile.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Busan, Korea. golddent@pusan.ac.kr <golddent@pusan.ac.kr>
authors.forename: Hyeon-Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Gary Shun-Pan
authors.initials: GS
authors.lastname: Cheung
authors.forename: Chan-Joo
authors.initials: CJ
authors.lastname: Lee
authors.forename: Byung-Min
authors.initials: BM
authors.lastname: Kim
authors.forename: Jeong-Kil
authors.initials: JK
authors.lastname: Park
authors.forename: Soon-Il
authors.initials: SI
authors.lastname: Kang
mesh_terms: D003198:Computer Simulation; D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D004867:Equipment Design; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D009532:Nickel; D044367:Phase Transition; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium