TY - JOUR
T1 - Multimethod analysis of three rotary instruments produced by electric discharge machining technology
AU - Silva, Emmanuel J. N. L.
AU - Ajuz, Natasha C.
AU - Martins, Jorge N. R.
AU - Antunes, Bernardo R.
AU - Lima, Carolina O.
AU - Vieira, Victor T. L.
AU - Braz-Fernandes, Francisco Manuel
AU - Versiani, Marco A.
N1 - Funding Information:
The authors deny any conflicts of interest related to this study. This study was partially funded by CNPq and FAPERJ. 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. Fernanda Carvalho is acknowledged for running the DSC tests on the instruments.
Publisher Copyright:
© 2023 British Endodontic Society. Published by John Wiley & Sons Ltd.
PY - 2023/6
Y1 - 2023/6
N2 - Aim: This study aimed to compare three rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability. Methodology: HyFlex EDM (25/~), Neoniti (25/.06), EDMax (25/.06) and ProTaper Gold (25/.08v) instruments (n = 58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way anova post-hoc Tukey and Kruskal–Wallis post-hoc Dunn's tests (α = 5%). Results: All instruments had asymmetrical blades, no radial lands, no major defects and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21°C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p >.05), while EDMax and ProTaper Gold had similar time to fracture (p =.841), maximum bending load (p =.729), and cutting ability (p =.985). ProTaper Gold showed the highest torque to failure (p <.001) and HyFlex EDM had the lowest buckling resistance (p <.001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p >.05). Conclusions: Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.
AB - Aim: This study aimed to compare three rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability. Methodology: HyFlex EDM (25/~), Neoniti (25/.06), EDMax (25/.06) and ProTaper Gold (25/.08v) instruments (n = 58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way anova post-hoc Tukey and Kruskal–Wallis post-hoc Dunn's tests (α = 5%). Results: All instruments had asymmetrical blades, no radial lands, no major defects and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21°C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p >.05), while EDMax and ProTaper Gold had similar time to fracture (p =.841), maximum bending load (p =.729), and cutting ability (p =.985). ProTaper Gold showed the highest torque to failure (p <.001) and HyFlex EDM had the lowest buckling resistance (p <.001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p >.05). Conclusions: Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.
KW - differential scanning calorimetry
KW - endodontics
KW - mechanical properties
KW - micro-CT
KW - nickel–titanium alloy
KW - scanning electron microscopy
UR - http://www.scopus.com/inward/record.url?scp=85153584431&partnerID=8YFLogxK
U2 - 10.1111/iej.13915
DO - 10.1111/iej.13915
M3 - Article
C2 - 36942476
AN - SCOPUS:85153584431
SN - 0143-2885
VL - 56
SP - 775
EP - 785
JO - International Endodontic Journal
JF - International Endodontic Journal
IS - 6
ER -