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Stress distribution of three NiTi rotary files under bending and torsional conditions using a mathematic analysis
Author(s) -
Kim T. O.,
Cheung G. S. P.,
Lee J. M.,
Kim B. M.,
Hur B.,
Kim H. C.
Publication year - 2009
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.1365-2591.2008.01481.x
Subject(s) - nickel titanium , materials science , structural engineering , bending , stress (linguistics) , orthodontics , composite material , engineering , medicine , shape memory alloy , linguistics , philosophy
Aim To compare and evaluate the stress distribution of three NiTi instruments of various cross‐sectional configurations under bending or torsional condition using a finite‐element analysis model. Methodology Three NiTi files (ProFile, ProTaper and ProTaper Universal) were scanned using Micro‐CT to produce a three‐dimensional digital model. The behaviour of the instrument under bending or torsional loads was analysed mathematically in software (ABAQUS V6.5‐1), taking into consideration the nonlinear mechanical characteristic of NiTi material. Results ProFile showed the greatest flexibility, followed by ProTaper Universal and ProTaper. The highest stress was observed at the surface near the cutting edge and the base of (opposing) flutes during cantilever bending. Concentration of stresses was observed at the bottom of the flutes in ProFile and ProTaper Universal instruments in torsion. The stress was more evenly distributed over the surface of ProTaper initially, which then concentrated at the middle of the convex sides when the amount of angular deflection was increased. Conclusion Incorporating a U‐shaped groove in the middle of each side of the convex‐triangular design lowers the flexural rigidity of the origin ProTaper design. Bending leads to the highest surface stress at or near the cutting edge of the instrument. Stress concentration occurs at the bottom of the flute when the instrument is subjected to torsion.