Stainless Steel Block Research Articles

Comparison of cyclic fatigue resistance of four pediatric rotary file systems at body temperature: an in vitro study

BackgroundThe aim of this study was to compare the cyclic fatigue resistance (CFR) of the newly developed pediatric nickel-titanium (NiTi) rotary file systems for root canal preparation of primary teeth.MethodsEighty pediatric NiTi rotary file systems files were used in this study, including 20 EasyInSmile X-Baby (25/0.04), 20 Scope miniScope (25/0.04), 20 EndoArt Pedo Gold (25/0.04), and 20 EndoArt Pedo Blue (25/0.04) files. Static CFR tests; performed on a custom-made stainless steel block with an inner diameter of 1.5 mm, an angle of curvature of 60° and a curved artificial canal with a radius of curvature of 5 mm. The test system was filled with distilled water and the temperature was kept constant at 35 ± 1 °C. The files were rotated in the simulated canal until fracture occurred. The number of cycles to failure (NCF) data was recorded, and all the fracture surfaces of the files were evaluated using scanning electron microscopy (SEM). One-way ANOVA and Tukey tests were used for statistical analysis of the data, and the significance level was set at p < 0.05.ResultsEndoArt Pedo Blue showed the highest NCF values (2668.10 ± 755.26), while the miniScope showed the lowest NCF values (453.65 ± 72.51), with a statistically significant difference between all the tested file systems (p < 0.05). There was no statistical difference in terms of fractured fragment lengths among all tested files (p > 0.05).ConclusionThe EndoArt Pedo Blue file system showed the best CFR performance among the four file systems specifically designed for primary teeth.

Effect of Mechanical Compression on Ionic Conductivity of PEO-LiTFSI Solid Polymer Electrolytes

In the field of energy storage materials, the development of robust solid polymer electrolytes for lithium-ion batteries necessitates an understanding of ionic conductivity when subjected to mechanical stress. Accurate determination of ionic conductivity requires knowing the electrolyte thickness, which is subject to volumetric changes during charging and discharging of solid-state batteries. However, compressive stress reduces the thickness of the electrolyte by an indeterminate amount.This work presents experimental measurements of ionic conductivity as a function of compressive stress, using poly(ethylene oxide) and with bis(trifluoromethane) sulfonimide (PEO-LiTFSI). In this study, we not only measure the stress-strain response of the electrolytes directly, but also monitor the extent of compression during electrochemical impedance spectroscopy (EIS). Compression was applied up to 50% strain for three consecutive cycles, and the typical thickness for the fabricated electrolytes was ~50 µm. EIS testing was performed by using an impedance analyzer, with the electrolyte placed between stainless steel blocking electrodes. Bulk resistance was determined by equivalent circuit modeling of impedance between 100 Hz and 2 MHz. Ionic conductivity κ was calculated from bulk resistance Rb , electrolyte thickness h, and cross-sectional area A, according to the equation κ = h/(Rb·A).In order to measure both stress and deformation simultaneously, a custom positioning stage was engineered to apply prescribed compression. The apparatus has an in-line load cell for force measurements and a laser triangulation sensor for position tracking with submicron resolution. We found that the bulk resistance at room temperature decreases exponentially, with magnitude reduced by approximately five-fold when subjected to compressive stress up to 10 MPa. Beyond ~7 MPa, bulk resistance values were no longer dependent on the amount of applied compression.In addition to mechanical measurements, changes in crystalline and amorphous regions were correlated to the magnitude of compressive stress and the measured ionic conductivity of the electrolyte. For optical imaging with simultaneous EIS measurements, glass slides coated with an indium tin oxide (ITO) film were used instead of stainless steel disks. The extent of crystallinity was visualized by optical microscopy of spherulites through a viewing window when compressed between rigid plates.Figure 1. Apparatus (left) and representative ionic conductivity vs. compressive stress (right) data for a PEO-LiTFSI polymer electrolyte. Figure 1

Surface roughness and cyclic fatigue resistance of a novel shaping system: An in-vitro study.

Recently developed Nickel-Titanium (NiTi) instruments with practical changes have resulted in safer instrumentation. In addition, topographical features on the file surface are a contributing factor to clinical durability. Therefore, this study aimed to investigate both the cyclic fatigue resistance and the roughness change of MTwo and Rotate instruments (VDW, Munich, Germany). Each instrument (n = 6/each group) was scanned with an atomic force microscopy prior to and after instrumentation. In addition, cyclic fatigue testing was conducted for each instrument (n = 11/each group) with stainless-steel blocks, including 45°-60°-90° degrees of curvature milled to the instruments' size. The roughness parameters increased for both systems after instrumentation (p<0.05). Both systems presented an increased roughness following instrumentation (p<0.05). The cyclic fatigue resistance was lowest at 90° for both systems (p<0.05), whereas the Rotate files presented a higher resistance than that of the Mtwo files (p<0.05). Compared to the Mtwo files, Rotate files presented better resistance, while the resistance decreased as the curvature increased.

Edge Response and Defect Detectability in Flat Panel Digital Radiography

Defect detectability studies are used in nondestructive testing to ascertain the reliability of the method of inspection. In digital radiography, with the growing prevalence of automation of quality control processes by image processing and machine learning, a threshold detection criterion based on quantifiable data from the digital radiograph could be explored. The use of the parameter contrast-to-noise ratio (CNR) of defect signal as a probability of detection (POD) threshold criterion is explored in this paper. A stainless steel block containing artificial defects of known dimensions and location is radiographed by a flat panel detector, and an empirical POD curve is constructed. Before the POD study, the edge response of the flat panel system is studied to ensure noninterference of adjacent defect signals, gain insights about the lateral spread of the defect signal, and provide information to choose the region of interest for CNR calculation. The effect of noise on the POD using CNR as the threshold criterion is also included in the present study. The use of CNR-based POD models for digital radiography to aid the comparison and development of automatic defect detection models is also discussed.

Fabrication of micro tools using electrochemical machining with a reciprocating block electrode

Micro parts are increasingly being used in many applications. The machining of micro parts is inevitably dependent on micro tools, which play a key role in limiting the feature size and controlling the dimensional accuracy. However, the fabrication of micro tools is currently inefficient. This paper presents a novel electrochemical machining (ECM) method in which a reciprocating block (RBECM) is used as the tool electrode. In RBECM, the cylindrical workpiece reciprocates up and down in a straight line along its axis, while the block electrode simultaneously makes a feed movement. A mathematical model of the cutting edge length and width was derived to predict the size of the cutting edge tools. The results indicate that the model could achieve a good prediction accuracy. In addition, the effects of machining time on cutting edge width were experimentally investigated. Three types of stainless steel cutting edge tools with cutting edge widths of approximately 1/4, 1/2, and 3/4 of the diameter were successfully fabricated using a 5-mm-thick stainless steel block. The experimental results indicate that the machining time could be significantly reduced by 97.83–99.5% compared to the ECM method using a tensioned metal wire as the cathode.

Effect of NaOCl on cyclic fatigue resistance.

The impact of 5.25 percent NaOCL on the resistance offered by TruNatomy, Hero Gold and ProtaperGold against cyclic fracture as against the treatment of NiTi rotary files with distilled water is of interest to dentists. Inside the stainless steel blocks, man-made canals were created for the purpose of testing the cyclic fatigue. 60 endodontic files were taken as study specimens. It was observed that values of number of cycles to fracture in NaOCl among three file systems were in the order of TruNatomy (1053.50 ± 134.81)>Hero Gold (652.66 ± 58.66) > ProtaperGold (494.50 ± 47.69). The TruNatomy file system reflected greatest cyclic fatigue resistance. It was also found that cyclic fatigue resistance in NiTi rotary files studied here is not hampered by 5.25% NaOCl.

Investigation of Performance Estimation Methods Validity of Thermoelectric Module

The thermoelectric cooling system is now widely used in small-capacity applications. This system is designed to remove the heat by using a thermoelectric module thus the selected object can be maintained at the required range of temperature. The performance of the thermoelectric module system can be estimated by using the information from the technical datasheet issued by the manufacturer. Two commonly used methods for estimating the cooling capacity of the system are performance curve and energy balance. This study aims to investigate the accuracy of those two methods compared with the experimental results. The experiment was performed by maintaining the hot side temperature at 50 °C. To estimate the cooling capacity, the heat conduction on the stainless-steel block was calculated. The results showed the estimated cooling capacity of the thermoelectric system was up to 48% and 10.1% higher than the experimental result by using energy balance and performance curve methods, respectively. It implied that the performance curve method is more accurate than the energy balance method.

Comparing the EdgeFile X3, GenEndo, HeroGold, and ProTaper Gold Rotary Instruments Regarding the Effect of Different Concentrations and Temperature of NaOCl on Cyclic Fatigue Resistance.

This research was carried out with the objective of comparison between GenEndo, Protaper Gold, Hero Gold and EdgeFile X3 regarding the effect of different concentrations of NaOCl. About 720 study specimens were included in the study. They were divided into four groups. Each group consisted of 180 files. Group A: GenEndo, Group B: Protaper Gold, Group C: Hero Gold, Group D: EdgeFile X3. Each group of instruments were further subdivided into nine subgroups (n = 20 for each subgroup). Testing of the cyclic fatigue was carried out in artificial canals which were prepared inside the blocks of stainless steel. The stainless steel blocks with artificial canals were established in a receiver that was packed with experimental solutions like distilled water, 5.25% NaOCl and 2.5% NaOCl. The adjustment of temperature was done at 25, 37, and 60°C. The rotation of the instrument was carried out inside the artificial canal as per the instructions of the manufacturer. The instrument was rotated until it got fractured. The time taken by the instrument to fracture was recorded in seconds. The number of cycles to fracture (NCF) was analyzed with the help of the equation (NCF = time to fracture × rpm/60). Surfaces at the site of fracture were examined with the help of a scanning electron microscope (EVOLS10, ZEISS) at magnification (300x and 2000x). It was noticed that there was a statistically significant increase in cyclic fatigue when sodium chloride was used as an endodontic irrigant instead of distilled water. The increase in cyclic fatigue was also observed when 5.25% sodium chloride was used instead of 2.5% sodium hypochlorite. Cyclic fatigue increased on change in temperature from 25 to 37°C and from 37 to 60°C. The difference was statistically significant (p < 0.05). It was observed that resistance against cyclic fatigue on treatment with different irrigation solutions at different temperatures was in the order of GenEndo > Protaper Gold > Hero Gold > EdgeFile X3. The resistance against cyclic fatigue in new NiTi rotary files can be affected significantly by different concentrations of sodium hypochlorite irrigant solution and the GenEndo rotary endodontic instrument has the maximum resistance against cyclic fatigue. Irrigation of the root canal with irrigants, such as sodium hypochlorite (NaOCl) has been recommended strongly. NaOCl is used in the range of 0.5 and 6.5% concentration owing to its antimicrobial activity and tissue dissolution activities, particularly at higher temperatures. It has been postulated that fatigue of rotary endodontic instruments can be influenced by adjoining medium and their concentration.

Experiment and Analysis of Load-Bearing Insulations for Slabs Thermal Breaks composed by H-Shaped Stainless Steel and UHPC Blocks

Experiment and Analysis of Load-Bearing Insulations for Slabs Thermal Breaks composed by H-Shaped Stainless Steel and UHPC Blocks

Influence of sodium hypochlorite on cyclic fatigue resistance of nickel-titanium instruments: A systematic review and meta-analysis of in vitro studies.

This systematic review/meta-analysis investigated the influence of NaOCl on cyclic fatigue resistance of endodontic NiTi instruments. A systematic search until July 2022 in PubMed/MEDLINE, Embase, Scopus, Web of Science, SciELO, Cochrane Library, and grey literature was conducted. According to the PECOS strategy, only in vitro studies evaluating the effects of NaOCl on the cyclic fatigue resistance of NiTi instruments were eligible. Cyclic fatigue resistance was the primary outcome. A modified Joanna Briggs Institute's Checklist was used for risk of bias assessment. Of the 2,445 records screened, 37 studies were included. Most studies used simulated canals made of stainless-steel block with severe to moderate curvatures. NaOCl concentration varied from 1-6%, mainly at 37°C. Regarding fatigue resistance, 23 studies using 1.2% to 6% NaOCl showed a reduction in the resistance compared to the control groups, especially when pre-heated. Four meta-analyses were performed according to the tested NiTi systems. The meta-analyses indicated that the PTU F2 files had higher reduction of fatigue resistance after exposure to 5.25% NaOCl; no differences between NaOCl and no immersion were observed for Reciproc R25, WaveOne 25.08, and WaveOne Gold Primary files. Included studies had low risk of bias. NaOCl appears to reduce cyclic fatigue resistance of certain NiTi files, especially when they are pre-heated, particularly in conventional NiTi files compared to some heat-treated instruments. It is possible that the temperature of the solution may have a greater influence on resistance than NaOCl itself. Important to note that an overall tendency toward no significant influence was observed among various systems. Precautions are necessary when a pre-heated high-concentration NaOCl is used to enhance its properties during root canal preparation, mainly using conventional wire.

Optimization of Process Parameters and Mechanical Properties of 316L Stainless Steel Block via Arc Additive Manufacturing

_ A study was conducted on the influence of current, spacing, current mode, and arc length on the formation of adjacent weld overlays in the 316L stainless steel block melting process using an extremely inert gas-shielded arc additive manufacturing method. The main defect observed during the formation of adjacent weld overlays was the incomplete fusion at the bottom. When using direct current, low current and short arc length could ensure the flatness of the overlay surface, and the fusion at the bottom of the adjacent weld overlays was improved, but the problem of incomplete fusion remained unresolved. When using pulse current, low current, short arc length, and continuous welding method could solve the problem of bottom fusion of adjacent weld overlays. Due to the thermal influence during the accumulation of adjacent weld overlays, the microstructure inside the weld overlay was uneven, and the crystallographic texture in the entire weld overlay was not formed. With a pulse current of 80 A, adjacent weld overlay spacing of 4.5 mm, travel speed of 200 mm/min, dry elongation of 10 mm, and arc length of 2 mm, the tensile strengths of the block in the X, Y, and Z directions were 568.5, 570.3, and 550.7 MPa, respectively, and the fracture elongations were 46%, 48%, and 43.3%, respectively. The strength and plasticity in the Z-direction were lower than those in the X and Y directions. Keywords 316L stainless steel; arc additive manufacturing; incomplete fusion; pulse current

Benchmarking of Stainless Steel Cube Neutron Leakage in Research Center Rez

Integral experiments covering neutron leakage from geometrically simple assemblies with a 252Cf source inside are very valuable tools usable in the validation of transport cross-section data since geometric uncertainties play a much smaller role in simple geometric assemblies than in complex assemblies as for example reactor pressure vessel geometry. Since 252Cf spontaneous fission is a standard neutron source, the uncertainties connected with the source neutron spectrum can be even neglected. The paper refers to validation efforts of neutron leakage from an ~50 × 50 × 50-cm stainless steel block in the Research Center Rez. Both the neutron leakage flux at a distance of 1 m from the center of the cubical assembly using stilbene spectrometry and activation rates at different positions of the assembly were evaluated. In addition to experiments, main sources of uncertainty were identified and evaluated. The results of the stilbene measurements are consistent with the activation measurement results.

Surface morphology evolution of GTD-450 stainless steel during laser powder bed fusion

GTD-450 is a new type of maraging stainless steel. It has a wide application prospect in the additive manufacturing of complex components such as GTD-450 compressor blades using L-PBF technology. In this study, a multi-scale numerical model was used to simulate the whole process of L-PBF forming of GTD-450 stainless steel block. This numerical model can describe the evolution process of L-PBF forming temperature field, melt flow field and melt free surface. With the help of simulation results, the surface morphology of GTD-450 stainless steel formed under different layers is clarified. The experimental and numerical data of surface morphology are in good agreement, which verifies the reliability of the numerical model. Based on the experimental results, the influence mechanism of melt pool behaviour and thermal history on melt solidification behaviour was discussed, and the development process of L-PBF block surface morphology under the influence of melt pool behaviour was explained.

Relationship between Occlusal Vertical Dimension and Tongue Pressure in Complete Denture Wearers

Data on estimating the vertical dimension of occlusion（VDO）for fabricating a complete denture based on tongue pressure, which is related to masticatory and swallowing functions, are scarce. This study aimed to examine the changes in tongue pressure on raising or lowering of the VDO from the most comfortable position（MCP）. Ten edentulous, including Eichner C3, patients with existing dentures（six men and four women; mean age, 78.6±7.14 years）were recruited from a hospital setting. Twelve different height-positioning stimulus stainless-steel blocks were used（from +1 mm to 6 mm and +9 mm and from -1 mm to -4 mm）. VDO from the most comfortable position （MCP）and the tongue pressure at the respective height were measured. One-way analysis of variance（ANOVA）and Dunnett’s test were performed to analyze the differences in tongue pressure at different VDOs. There were no significant differences between the stimulus intervals（-1 to -4 mm, p = 0.99）on lowering VDO from MCP. Tongue pressure decreased marginally when the VDO was raised +5 mm from the MCP（p=0.054）; it continued to show a significant decrease at +6 mm（p=0.041）and +7 mm（p=0.035）from MCP. Tongue pressure did not change significantly when VDO was lowered and raised to +5 mm from MCP. These results suggest that VDO may be set to 5 mm from MCP when fabricating new complete dentures.

The microstructure and mechanical properties of 316L austenitic stainless steel prepared by forge and laser melting deposition

In this study, the 316L austenitic stainless steel blocks were prepared by forge and laser melting deposition (LMD). To clarify the effect of deposition strategy on microstructure and mechanical properties of 316L samples, three different deposition strategies (30°, 67° and 90°) are selected. The results showed that the molten pool of LMDed sample consists of a large number of coarse columnar grains and a few irregular equiaxed grains, which contains plentiful cellular and fiber sub-structures with an average size of ∼4 μm. The LMD process can significantly improve the comprehensive mechanical properties perpendicular to the build direction of 316L austenitic stainless steel, which was mainly attributed to sub-structural strengthening, but also slightly due to the local misorientation and texture distribution. The yield strength and ultimate tensile strength of R90 sample increased to 484.0 MPa and 627.6 MPa from 305.3 MPa to 601.4 MPa of as-forged 316L, and its elongation has a negligible reduction. The sub-structures produced during solidification have the same fine grain strengthening effect as the high-angle grain boundary, and the yield strength and average size of sub-structures conform to the Hall-Petch relationship. The deterioration of the plastic deformation capacity of the R67 sample is attributed to the larger thermal stress and texture distribution with a certain hard orientation. The plastic deformation of as-forged sample is mainly coordinated by multi-system slip, while twinning and slip are activated together during deformation of LMDed 316L austenitic stainless steel. The grain boundary map indicated that the strain location preferentially appears along cell wall of sub-structures, which promotes the formation of sub-grain boundaries during deformation of LMDed samples.

Electrochemical Studies on Poly(Ethylene Oxide) Based Gel-Polymer Electrolytes for Magnesium-Ion Batteries

Research and development works in the field of multi-valent metal-ion batteries are intensified these days because of the abundance of multi-valent elements such as magnesium, aluminum, calcium and so on in the Earth’s crust. Magnesium-ion batteries are particularly important, because they have high theoretical volumetric capacity (3832 mAh cm-3) compared to that of well-known lithium-ion batteries (2062 mAh cm-3). However, there are potential challenges, typically, designing suitable electrolytes with sufficient ambient temperature ionic conductivities is a major challenge. In this work, a set of gel-polymer electrolytes based on poly (ethylene oxide) (PEO) host polymer and magnesium acetate (Mg(CH3COO)2) ionic salt have been synthesized and characterized by electrochemical impedance spectroscopy (EIS), DC polarization and linear sweep voltammetry (LSV) techniques. Among the compositions studied in this work, the optimized PEO-Mg(CH3COO)2-EC-PC electrolyte (6:14:40:40 wt.%) showed an ambient temperature ionic conductivity of 6.1x10-5 S cm-1. Ionic conductivity vs inverse temperature showed Arrhenius behavior with almost same activation energies (0.15 - 0.18 eV) for all the compositions. DC polarization studies performed with stainless steel blocking electrodes under an externally applied voltage of 1V showed that the highest conducting composition is dominantly an ionic conductor with an ionic transference number of 0.99. The electronic contribution to conductivity was found to be almost negligible, which is desirable to avoid short circuits within the cell. The LSV test on highest conducting composition revealed that the electrochemical stability window of these electrolytes is about 2.2 volts.

Comprehensive stainless steel neutron transport libraries validation

Stainless steel is an important material that is relied upon to perform consistently over time in the nuclear industry. The paper focuses on the validation of different stainless steel neutron transport libraries. The validation was performed by means of samples activation in different positions and also the measurement of the fast neutron spectrum in the energy range of 1–12 MeV using a scintillation stilbene detector. Stainless steel was used in the form of a block with a hole for the neutron source. The dosimetric reactions used for validations were 58Ni(n,p)58Co, 93Nb(n,2n)92mNb, 197Au(n,2n)196Au, 63Cu(n,g)64Cu, 197Au(n,g)198Au, 115In(n,ń)115m1In, 115In(n,g)116m1In, 55Mn(n,g)56Mn, and 181Ta(n,g)182Ta. The experimental data were compared with MCNP6.2 calculations employing ENDF/B-VIII.0, ENDF/B-VII.1, JEFF-3.3, JEFF-3.2, CENDL-3.1, JENDL-5 and INDEN transport libraries. These libraries were used for the simulation of the stainless steel block. The activation foils cross sections were taken from the IRDFF-II library. An intense standard neutron 252Cf(sf) source was placed in the centre of the stainless steel block. INDEN library is the best for the calculation of neutron flux in the range of 1–12 MeV. For the activation detectors placed at the various distances inside the block, the best library depends on the reaction studied.

Design and construction of the magnetic mirror magnets of the space plasma environment research facility (SPERF)

The Space Plasma Environment Research Facility aims to research the space plasma physics in the laboratory. Two elliptical magnets are used to form a magnetic mirror field simulating the interplanetary magnetic field to investigate the magnetic reconnection at the magnetopause and magnetotail of the earth on the ground. To perform the research, the issues facing the magnets in terms of high pulsed current, vacuum, plasma, and mechanical support must be resolved. The paper presents their design and construction process to settle these issues. A series of measures are adopted to enhance insulation, reduce the gas leakage, and avoid tip discharge, ranging from the dielectric layers to the Inconel spraying. A transition structure considering the effect of the strong pulsed current is designed for connecting the magnet's leads to the cables of its pulsed power supply. In addition, a supporting and motion mechanism is proposed to hold the magnets and drive them to move. The strength of the mechanism is assessed by the static mechanical analysis for the extreme magnetic force load. Meanwhile, a connection scheme compatible with the supporting and motion mechanism is proposed to guide the cables through the vacuum vessel. The great mechanical stress occurring at the interface between the cables and the stainless-steel blocks due to the sheared magnetic force is reduced considerably by a fixing plate. The results in the paper are valuable for designing the magnet conducting a large pulsed current in the vacuum environment for plasma applications.

지르코니아 나노입자 기반 나노패턴 금속 몰드 제작과 열가소성 재료의 복제성형 응용

Fabrication of a durable and strong nanopatterned mold insert using metal sheet and plate is important for molding of thermoplastic materials. Conventionally, the nickel stamper replicating a master pattern by electroforming process has been used for injection molding of nanotextured products such as Blu-ray media. However, a more facile and cheaper mold fabrication process is highly required for manufacturing of functional products based on nanostructured surface. In this study, zirconia nanoparticles were blended with UV curing polymer to fabricate a polymer nanocompositebased nanopattern mold. Compared to the cured pure Ormostamp, the modulus of elasticity of the nanocomposite filled with approximately 54 vol% of zirconia nanoparticles increased by 160 times. Additionally, the modulus of elasticity reached 197 ㎬ by thermal decomposition of the UV-Cured polymer and post-annealing at 800°C of the nanoparticle layer. The nanopatterns were formed on stainless steel sheet and block, and applied to hot embossing of the PMMA films and injection molding of the COC materials, respectively. No deterioration of the mold occurred during the hot embossing 30 times and the injection molding 600 shots. Nanoparticle-enhanced UV curing nanocomposites or post-heat treatment methods are cost-efficient and easy, because many molds can be manufactured from one master pattern.

In vitro evaluation of cyclic fatigue resistance of thermally treated novel nickel-titanium rotary instruments

The objective of this study was to evaluate the cyclic fatigue resistance of novel NiTi files (subjected to heat treatment) using the in vitro model (artificial canal). Twelve ProDesign Logic instruments - PDL 25/.06 (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil) and 12 Protaper Next X2 instruments - PTN (tip 25) were included in this research. The Static cyclic fatigue test was performed with a grooved stainless steel block simulating a canal of 1,5 mm diameters, a 60o angle of curvature and 5 mm radius. The files were positioned inside the artificial canal and rotated until the fracture occurred. Using the time until fracture (seconds) and the number of rotations per minute (RPM), the number of cycles until fracture (NCF) was calculated and the length of ruptured fragments was registered. Three samples from each group were analyzed in Scanning Electronic Microscopy (SEM) to characterize the metal rupture. Data were analyzed using the Mann-Whitney non-parametric test and the level of significance considered was p&lt;0.05. PDL obtained a mean value of 956,0 NCF (352,0 - SD) and PTN achieved 391,0 NCF (36.7 - SD) with statistical significance between the groups (p &lt; 0.001). There was no statistical difference on fragment length (p &gt; 0.05). SEM analysis showed features compatible with ductile fracture. ProDesign LOGIC files showed higher NCF than Protaper Next X2. There was no difference between groups considering the length of the ruptured fragment.