Morphological and structural variations of Nickel-Titanium endodontic instruments subjected to instrumentation loads: in vitro study

Abstract

To identify morphological and structural variations in WaveOne Gold Primary® related to artificial canal instrumentation, experiments were conducted on artificial canals fabricated from Diallyl-Phthalate to identify morphological and structural variations in WaveOne-Gold-Primary (n=10) endodontic instruments. The canals were immersed in water at 38° C ± 1°C and irrigated with NaClO-5%. The instruments were examined using optical microscopy to perform Cauchy strain measurements. Lattice parameters, microstrains, and texture were determined using X-ray diffraction. Scanning electron microscopy was employed to identify shear bands and fracture characteristics. Statistical analysis was performed using analysis of variance and Bonferroni tests. Untwisting and elongation were pronounced at approximately 54 pecks; fracture occurred at 62 pecks. Mathematical models were proposed to correlate strains and texture with the number of pecks. Substantial plastic deformations caused by the torsion-adhesion mechanism and associated with ductile fracture were observed, and grain domain alterations were identified. The difference between the sample's relative intensities in X-ray diffraction demonstrated texture changes between 0 and 20 pecks and a subsequent change after 62 pecks.

Keywords

• Endodontic instrument
• NiTi alloy
• Optical microscopy
• XRD
• SEM
• Artificial root canal