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Diamond-like carbon coating enhances mechanical performance of NiTi rotary instruments
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Resumo(s)
Aim: This study aimed to evaluate the impact of diamond-like carbon (DLC) surface treatment on the mechanical properties of nickel–titanium (NiTi) rotary instruments. Methodology: One hundred and ten nickel–titanium instruments with a size of 25/.06 and a length of 25 mm, both with (n = 55) and without (n = 55) a DLC coating were selected and compared regarding their design (stereomicroscopy, scanning electron microscopy), metallurgy (energy-dispersive X-ray spectroscopy, differential scanning calorimetry), and mechanical performance (time to fracture, bending strength, buckling strength, cutting efficiency, and microhardness). Data were analysed using Mann–Whitney and independent Student's t-test (α = 5%). Results: The design analysis confirmed that both instruments had identical geometric features, similar spiral and tip designs, with DLC-coated instruments showing fewer surface irregularities and a multi-coloured appearance. Metallurgical analysis revealed identical transformation temperatures for both groups, with the R-phase starting at ~32°C, finishing at ~25°C during cooling, and the austenitic finish occurring at ~35°C. DLC-coated instruments demonstrated significantly superior cyclic fatigue resistance (p = 0.0028), lower bending load (p = 0.0294), lower cutting efficiency (p < 0.0001), and higher microhardness (p = 0.0019), whilst no difference was observed in terms of buckling strength (p = 0.3569). Conclusions: Diamond-like carbon surface treatment significantly enhanced cyclic fatigue resistance, flexibility, and microhardness of NiTi rotary instruments without compromising their structural integrity.
Descrição
Funding Information: This study was partially funded by FAPERJ and CNPq. The authors acknowledge Fernanda Carvalho for running the differential scanning calorimetry tests on the endodontic files. The Article Processing Charge for the publication of this research was funded by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) (ROR identifier: 00x0ma614). Publisher Copyright: © 2025 The Author(s). International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.
Palavras-chave
Diamond-like carbon coating Endodontics Mechanical properties Nickel–titanium instruments General Dentistry