BACKGROUND: Contemporary nickel-titanium (NiTi) rotary endodontic instruments had a revolutionary impact on the success of root canal treatment. AIM: To evaluate the flexibility, microstructure and elemental analysis of four different recent NiTi rotary instruments, namely; Wave One Gold, TF adaptive, HyFlex EDM and Gr_Reciproc Blue compared to conventional Protaper Universal (F2). MATERIAL AND METHODS: The NiTi rotary files were subjected to cantilever bending test to evaluate their flexibility. The microstructural characteristics and elemental analysis were examined via scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDX). RESULTS: The TF adaptive, HyFlex EDM and Wave One Gold endodontic files showed significantly lower cantilever bending values (i.e., higher flexibility) than Protaper F2 and Gr_Reciproc Blue (p < 0.05). The SEM micrographs showed that the bulk of all examined files showed multiple striations due to the cutting process, on the other hand, their external surfaces were different: The Protaper Universal F2 showed multiple voids, while the TF Adaptive surface exhibited more uniform structure. The Hyflex EDM had a crater-like surface, whereas Wave one Gold showed machining grooves with minimum defects, while Reciproc Blue displayed machining grooves with random scratch lines. There was a significant difference in bulk and surface elemental analysis of the various examined files, yet composed mainly of the same elements. CONCLUSION: Chemical composition, heat treatment, manufacturing process and geometrical design of the NiTi rotary instrument have a great influence on their flexibility and microstructure.

Chitosan, glycidyl methacrylate (synthetic polymer) and magnetite are combined to produce novel magnetic macro-reticular hybrid synthetic–natural materials which are shown to be effective sorbents for RBBR ions.

Different concentrations of nickel oxide (NiO) nanoparticles were successfully inserted into polystyrene (PS) polymer matrix using the solution casting method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high-resolution scanning electron microscope (SEM), and UV-Vis techniques are used to characterize the nanocomposites. XRD, SEM, and FT-IR results indicate that PS and NiO nanoparticles have a good interaction and a high degree of complexity. Using UV-Vis technique, the absorbance of nanocomposites is improved by increasing the nanofiller content. Both the Urbach energy (EU) and the optical energy gap (Eg) were calculated using the Urbach relation and the Tauc model. Refractive indices values of nanocomposites display raising trend with NiO content which promote PS/NiO nanocomposites for use in photonic applications and designing optical devices. Nanocomposites' electrical conductivity was also investigated. The electrical conductivity of the nanocomposites has increased significantly due to the uniform dispersion of NiO nanoparticles and by increasing its content. Conduction is achieved by correlated barrier hopping (CBH).

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