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Dimensional characterization and mechanical behaviour of K3 rotary instruments
Author(s) -
Melo M. C. C.,
Pereira E. S. J.,
Viana A. C. D.,
Fonseca A. M. A.,
Buono V. T. L.,
Bahia M. G. A.
Publication year - 2008
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.1365-2591.2007.01368.x
Subject(s) - materials science , torsion (gastropod) , deflection (physics) , millimeter , torque , bending , bending moment , optics , composite material , structural engineering , physics , engineering , surgery , medicine , thermodynamics
Aim To correlate the mechanical behaviour in torsion, bending and fatigue tests of K3 instruments with their dimensional characteristics. Methodology Instrument length, tip angle, distance between blades (pitch length) and the diameter at each millimetre from the tip of sizes 20, 25 and 30, 0.04 taper and sizes 20 and 25, 0.06 taper K3 rotary instruments were measured in an optical microscope equipped with digital micrometers. The cross‐sectional area at 3 mm from the tip of the same instruments was determined using digital image analysis of scanning electron microscopy images. Maximum torque and angular deflection, as well as bending moment at 45° were measured according to specification of ISO 3630‐1. Fatigue resistance of instruments size 30, 0.04 taper, and sizes 20 and 25, 0.06 taper was determined in a fatigue test bench device. Results The analysed instruments presented no uniformity in the distance between adjacent blades, but the measured diameters at each millimetre from the tip were regular, showing compliance with manufacturing standards. Torque and bending moment of the tested instruments increased significantly with diameter and cross‐sectional area at 3 mm from the instrument tip. The fatigue resistance of the instruments showed a tendency to decrease as the diameter of the instruments increased. Conclusions The bending moment at 45° and the torsional resistance of K3 instruments can be predicted using instrument diameter and cross‐sectional area at 3 mm from the tip. Fatigue resistance decreased as the instrument diameter increased.