A Novel Protocol to Characterize Virtual Nickel–Titanium Endodontic Instruments

Publisher Copyright: © 2023 by the authors.The nickel–titanium (NiTi) instruments’ geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.publishersversionpublishe

Design, metallurgical characteristics, and mechanical performance

Funding Information: FMBF acknowledges the funding of CENIMAT/i3N by national funds through the FCT‐Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020‐2023. The authors ackowledge Fernanda Carvalho for running the differential scanning calorimetry tests on the endodontic files. Publisher Copyright: © 2023 The Authors. International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.Aim: To compare two flat-side single-file rotary instruments with three single-file reciprocating systems through a multimethod assessment. Methodology: A total of 290 new NiTi single-file rotary (AF F One Blue 25/0.06 and Platinum V.EU 25/0.06) and reciprocating (One Files Blue R25, Reciproc Blue R25, Reciproc R25) instruments were selected, carefully examined for any major deformations, and evaluated regarding their macroscopic and microscopic design, nickel and titanium elements ratio, phase transformation temperatures, and mechanical performance (time/rotation to fracture, maximum torque, angle of rotation, microhardness, maximum bending, and buckling strengths). One-way anova post hoc Tukey, T-test, and nonparametric Mood's median tests were used for statistical comparisons (α = 5%). Results: Tested instruments had identical blade counts and near-identical helical angles of approximately 24° (rotary instruments) and 151° (reciprocating instruments). The flat-side analysis revealed a few inconsistencies, such as discontinuity segments, different orientations, and gaps in the homogeneity of the bluish colour. Microscopically, flat-side instruments exhibited blade discontinuity and an incomplete S-shaped cross-section. The surface finish was smoother for One Files Blue and more irregular for both rotary instruments. There were distinct phase transformation temperatures amongst all instruments. All heat-treated instruments were in R-phase arrangement, and Reciproc was in R-phase plus austenite at test temperature (20°C). Compared with the reciprocating instruments, both flat-side instruments exhibited lower results in the cyclic fatigue tests using two different clockwise kinematics, maximum torque, angle of rotation, and maximum buckling strength (p <.05). The rotary systems also exhibited low flexibility (p <.05). AF F One Blue had the lowest microhardness, whilst Reciproc had the highest value. Conclusion: This multimethod investigation revealed that the flat-side rotary instruments underperformed the reciprocating instruments regarding cyclic fatigue (with two different clockwise kinematics), maximum torque, angle of rotation, maximum buckling strength, and flexibility. Manufacturing inconsistencies were also observed in some of the flat-side instruments, including discontinuity segments, different orientations, and in the homogeneity of their bluish colour given by the heat treatment.publishersversionpublishe

Multimethod Assessment of Design, Metallurgical, and Mechanical Characteristics of Original and Counterfeit ProGlider Instruments

Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.A multimethod study was conducted to assess the differences between original (PG-OR) and counterfeit (PG-CF) ProGlider instruments regarding design, metallurgical features, and mechanical performance. Seventy PG-OR and PG-CF instruments (n = 35 per group) were evaluated regarding the number of spirals, helical angles, and measuring line position by stereomicroscopy, while blade symmetry, cross-section geometry, tip design, and surface were assessed by scanning electron microscopy. Energy-dispersive X-ray spectroscopy and differential scanning calorimetry were used to identify element ratio and phase transformation temperatures, while cyclic fatigue, torsional, and bending testing were employed to assess their mechanical performance. An unpaired t-test and nonparametric Mann–Whitney U test were used to compare instruments at a significance level of 5%. Similarities were observed in the number of spirals, helical angles, blade symmetry, cross-sectional geometries, and nickel–titanium ratios. Measuring lines were more reliable in the original instrument, while differences were noted in the geometry of the tips (sharper tip for the original and rounded for the counterfeit) and surface finishing with PG-CF presenting more surface irregularities. PG-OR showed significantly more time to fracture (118 s), a higher angle of rotation (440°), and a lower maximum bending load (146.3 gf) (p 0.05). Although the tested instruments had a similar design, the original ProGlider showed superior mechanical behavior. The results of counterfeit ProGlider instruments were unreliable and can be considered unsafe for glide path procedures.publishersversionpublishe

A multimethod analysis

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.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.publishersversionpublishe

A Multimethod Assessment of a New Customized Heat-Treated Nickel–Titanium Rotary File System

Funding Information: Funding was provided by CENIMAT/i3N through national funds obtained through the FCT-Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023, and is acknowledged by F.M.B.F. Fernanda Carvalho is acknowledged for running the DSC tests of the files. This study was also partly funded by the Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), reference E-26/201.249/2021 and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), reference 403655/2021-8. Publisher Copyright: © 2022 by the authors.This study aimed to compare three endodontic rotary systems. The new Genius Proflex (25/0.04), Vortex Blue (25/0.04), and TruNatomy (26/0.04v) instruments (n = 41 per group) were analyzed regarding design, metallurgy, and mechanical performance, while shaping ability (untouched canal walls, volume of removed dentin and hard tissue debris) was tested in 36 anatomically matched root canals of mandibular molars. The results were compared using one-way ANOVA, post hoc Tukey, and Kruskal–Wallis tests, with a significance level set at 5%. All instruments showed symmetrical cross-sections, with asymmetrical blades, no radial lands, no major defects, and almost equiatomic nickel–titanium ratios. Differences were noted in the number of blades, helical angles, cross-sectional design, and tip geometry. The Genius Proflex and the TruNatomy instruments had the highest and lowest R-phase start and finish temperatures, as well as the highest and lowest time and cycles to fracture (p 0.05). No differences among tested systems were observed regarding the maximum torque, angle of rotation prior to fracture, and shaping ability (p > 0.05). The instruments showed similarities and differences in their design, metallurgy, and mechanical properties. However, their shaping ability was similar, without any clinically significant errors. Understanding these characteristics may help clinicians to make decisions regarding which instrument to choose for a particular clinical situation.publishersversionpublishe

A multimethod laboratory study

Funding Information: This study was partially funded by FAPERJ and CNPq. Funding Information: 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 Coordena\u00E7\u00E3o de Aperfei\u00E7oamento de Pessoal de N\u00EDvel Superior \u2010 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.Aim: To evaluate the influence of blade design (conventional, flat and hybrid) and metallurgical properties on the mechanical performance of nickel-titanium endodontic instruments. Methodology: Two hundred and seven NiTi instruments (25 mm in length) with three different blade designs were selected for analysis: conventional (n = 69, CC One Blue, size 25/0.08v), flat (n = 69, Platinum V.EU, size 25/0.06) and hybrid (n = 69, Flash Endo Power, size 25/0.06v). The instruments were evaluated regarding geometric design (scanning electron microscopy), alloy elements composition (energy-dispersive X-ray spectroscopy) and phase transformation temperatures (differential scanning calorimetry). Additionally, their mechanical behaviour was investigated by testing cyclic fatigue resistance, torsional resistance, bending resistance, buckling resistance, cutting efficiency and microhardness. Statistical significance was determined using One-Way anova and Kruskal–Wallis tests (α = 5%). Results: Platinum V.EU and Flash instruments exhibited design inconsistencies within the same lot, including nonstandard positioning and variations in the length of the flat side. All instruments were composed of a nickel-titanium alloy with equiatomic ratios of nickel and titanium. At 20°C, Flash instruments exhibited a mixed R-phase and austenitic arrangement, transitioning fully to austenitic at 36°C, while CC One Blue and Platinum V.EU displayed a complete R-phase at 20°C and retained a mixed R-phase and austenitic arrangement at 36°C. The CC One Blue exhibited superior performance in time to fracture (156 ± 34 s), maximum torque (1.5 N·cm) and buckling strength (372 ± 31 gf) (p <.0001), while no differences were found in maximum rotation angle (p =.602). In terms of flexibility, the Flash (328 gf) and CC One Blue (341 gf) outperformed the Platinum V.EU (376 gf) (p =.006). Flash (121 gf) and CC One Blue (137 gf) also outperformed Platinum V.EU (253 gf) in terms of cutting efficiency (p <.0001). Conversely, the Platinum V.EU demonstrated significantly higher microhardness (386 ± 45 HVN) compared to CC One Blue and Flash (p =.0340). Conclusions: Overall, instruments featuring either flat-side (Platinum V.EU) or hybrid (Flash) active blades demonstrated inferior mechanical performance compared to the conventional nonflat instrument (CC One Blue).publishersversionpublishe

Exploring the Impact of Heat Treatment and Machining Sequences on the NiTi Instruments Properties

Funding Information: This work was supported by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro and Conselho Nacional de Desenvolvimento Científico e Tecnológico. 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). Australian Endodontic Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Endodontology Inc.This study assessed how manufacturing sequence affects the metallurgical and mechanical properties of two nickel-titanium instruments: Procodile Q (heat-treated before machining) and Procodile +HT (heat-treated after machining). Both instruments (n = 74 each, size 25/0.06) were analysed for design, NiTi composition, phase transformation temperatures and mechanical performance (cyclic fatigue at 20°C and 35°C, torsional fatigue, bending load, buckling strength, cutting ability, microhardness and roughness). The Student's t-test and Mann–Whitney test were used for statistical analysis (α = 5%). Results showed that both instruments had similar design and composition. Procodile Q had a slightly higher austenitic start temperature and superior cyclic fatigue resistance at 20°C and 35°C (p 0.05). These findings suggest that the order of machining and heat treatment of Procodile instruments had minimal impact on overall performance, primarily affecting cyclic fatigue resistance and surface roughness.publishersversioninpres