Static and Cyclic Fatigue of Zirconia Materials Measured by Double Torsion

1996 ◽  
pp. 45-60
Author(s):  
J. Chevalier ◽  
C. Olagnon ◽  
G. Fantozzi
Keyword(s):  
Cyclic Fatigue ◽  
Double Torsion

Crack Propagation Behavior of Alumina with Different Grain Sizes under Static and Cyclic Fatigue

2006 ◽  
Vol 317-318 ◽  
pp. 449-452 ◽  
Author(s):  
Hassan El Attaoui ◽  
Malika Saâdaoui ◽  
Jérôme Chevalier ◽  
Gilbert Fantozzi
Keyword(s):  
Torsion Test ◽  
Cyclic Fatigue ◽  
Fatigue Threshold ◽  
Cyclic Loads ◽  
Grain Sizes ◽  
Propagation Behavior ◽  
Fine Grain ◽  
Grain Bridging ◽  
Crack Propagation Behavior ◽  
Double Torsion

A compliance function is used to quantify the shielding capacity of grain bridging, the degradation of which is the main cyclic fatigue mechanism in alumina. Materials with different grain sizes were processed and the fatigue experiments were performed using the double torsion test. Significant degradation is observed in the coarse grain material and a marked sensitivity to the loading level is outlined. At moderate loads, bridging degradation occurs prior to fatigue crack growth during an incubation period. At low cyclic loads, the shielding capacity can be entirely degraded, leading to a cyclic fatigue threshold equivalent to that of the fine grain material.

Cyclic fatigue comparison among endodontic instruments with similar cross section and different surface coating

2019 ◽  
Vol 68 (2) ◽  
Author(s):  
Eugenio Pedullà ◽  
Gianluca Plotino ◽  
Mauro Scibilia ◽  
Nicola M. Grande ◽  
Daniele De Santis ◽  
...  
Keyword(s):  
Cross Section ◽  
Surface Coating ◽  
Cyclic Fatigue

scholarly journals Effect of synchronous irrigation on cyclic fatigue of nickel-titanium instrument in the dynamic and static models

2021 ◽  
Vol 19 ◽  
pp. 228080002098740
Author(s):  
Haiyun Liu ◽  
Yanfeng Li ◽  
Guangquan Chai ◽  
Yuan Lv ◽  
Changjian Li ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Flow Rate ◽  
Dynamic Control ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Control Group ◽  
Time To Failure ◽  
Dynamic Tests ◽  
Significant Difference ◽  
Experimental Group

Objective: To evaluate the effect of synchronous water irrigation on the fatigue resistance of nickel-titanium instrument. Methods: A standardized cyclic fatigue test models were established, and five types of nickel-titanium instruments (PTU F1, WO, WOG, RE, and M3) were applied. Each instrument was randomly divided into two groups ( N = 12). There was synchronous water irrigation in the experimental group, and no water irrigation in the control group. Besides, ProTaper Universal F1 was randomly divided into 10 groups ( N = 20). In the static group, nickel-titanium instruments were divided into one control group (no irrigation, N = 20) and six experimental group (irrigation, N = 20) based on different flow rate, angle and position; while in the dynamic group, instruments were divided into one control group (no irrigation, N = 20) and two experimental group (irrigation, N = 20) based on different flow rate. The rotation time (Time to Failure, TtF) of instruments was recorded and analyzed. Results: According to the static experiments, the TtF of instruments in all experimental groups was significantly higher than that in the static control group. Besides, the dynamic tests of PTU F1 showed that the TtF in the experimental group was significantly higher than that in the dynamic control group. Compared with control group, the TtF in the experimental groups increased by at least about 30% and up to 160%. The static and dynamic tests of PTU F1 showed that the TtF of nickel-titanium instrument in all experimental groups was significantly higher than that in the control group. However, there was no significant difference between any two experimental groups. Conclusion: Regardless of dynamic or static model, TtF with irrigation was longer than that with non-irrigation, indicating that synchronous irrigation can increase the fatigue resistance of nickel-titanium instrument. However, different irrigation conditions may have the same effect on the fatigue resistance.

scholarly journals The Effects of Sterilization Procedures on the Cutting Efficiency of Endodontic Instruments: A Systematic Review and Network Meta-Analysis

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1559
Author(s):  
Mario Dioguardi ◽  
Enrica Laneve ◽  
Michele Di Cosola ◽  
Angela Pia Cazzolla ◽  
Diego Sovereto ◽  
...  
Keyword(s):  
Systematic Review ◽  
Selection Process ◽  
Meta Analysis ◽  
Indirect Comparison ◽  
Physical And Mechanical Properties ◽  
Surface Characteristics ◽  
Cyclic Fatigue ◽  
P Value ◽  
Cutting Efficiency ◽  
Dental Instruments

Sterilization processes guarantee the sterility of dental instruments but can negatively affect instrument features by altering their physical and mechanical properties. The endodontic instrumentation can undergo a series of alterations, ranging from corrosion to variation in the cutting angle and then changes in the torsional properties and torsional fatigue resistance. This systematic literature review and meta-analysis aims to investigate alterations to the cutting efficiency of endodontic instruments that are induced by procedures for their disinfection and sterilization. Methodologies adopted for this investigation follow the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. The following were used as search terms on PubMed and Scopus: “endodontic sterilization”, “endodontic autoclave”, “cyclic fatigue”, “torsional”, “cutting efficiency”, “sterilization”, “surface characteristics”, and “corrosion”. At the end of the selection process, 36 articles were identified, and seven of them are included in this systematic review. The results of a meta-analysis conducted for the use of 10 autoclaving cycles shows a standardized mean difference (SMD) of 0.80 with a p-value equal to 0.04 with respect to effect on cutting efficiency. The network meta-analysis, through direct and indirect comparison between the different autoclave cycles (0, 1, 5, 10, and 15 cycles), revealed that treatment involving 15 autoclave cycles produced the most robust results in terms of having the greatest effects in terms of altered cutting efficiency with a probability of 57.7% and a SUCRA (surface under the cumulative ranking) of 80%. The alterations in the effects on cutting efficiency appear to be triggered after five cycles of sterilization by heat (autoclave). In conclusion, the meta-analysis of the data indicates that the autoclave sterilization protocol must not be repeated more than five times to preserve cutting efficiency. Within the limitations of this review, we can therefore establish that sterilization by autoclaving alone results in steel and NiTi instruments becoming less efficient in cutting after five cycles, as measured by a reduction in cutting efficiency.

Influence of surrounding temperature and angle of file access on cyclic fatigue resistance of two single file nickel‐titanium instruments

2020 ◽  
Author(s):  
Giusy Rita Maria La Rosa ◽  
Carlotta Palermo ◽  
Sebastiano Ferlito ◽  
Gaetano Isola ◽  
Francesco Indelicato ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
File Access ◽  
Single File

scholarly journals Shaping and Centering Ability, Cyclic Fatigue Resistance and Fractographic Analysis of Three Thermally Treated NiTi Endodontic Instrument Systems

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5823
Author(s):  
Saulius Drukteinis ◽  
Vytaute Peciuliene ◽  
Ruta Bendinskaite ◽  
Vilma Brukiene ◽  
Rasmute Maneliene ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Fractographic Analysis ◽  
Significance Level ◽  
Root Canals ◽  
Topographic Features ◽  
New Instrument ◽  
Before And After ◽  
Number Of Cycles ◽  
Thermally Treated

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel–titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. µCT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 °C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey’s test was used for statistical analysis of the data; the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p > 0.05), but demonstrated significantly different resistance to cyclic fatigue (p < 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.

Evaluation of Asphalt Mixture Performance Using Cracking and Durability Tests at a Full-Scale Pavement Facility

2021 ◽  
pp. 036119812110218
Author(s):  
Amir Golalipour ◽  
Varun Veginati ◽  
David J. Mensching
Keyword(s):  
Performance Test ◽  
Asphalt Mixture ◽  
Performance Testing ◽  
Field Performance ◽  
Optimization Procedure ◽  
Cyclic Fatigue ◽  
Intermediate Temperature ◽  
Index Test ◽  
Reclaimed Asphalt ◽  
Indirect Tensile

In the asphalt materials community, the most critical research need is centered around a paradigm shift in mixture design from the volumetric process of the previous 20-plus years to an optimization procedure based on laboratory-measured mechanical properties that should lead to an increase in long-term pavement performance. This study is focused on advancing the state of understanding with respect to the value of intermediate temperature cracking tests, which may be included in a balanced mix design. The materials included are plant-mixed, laboratory-compacted specimens reheated from the 2013 Federal Highway Administration’s (FHWA’s) Accelerated Loading Facility (ALF) study on reclaimed asphalt pavement/reclaimed asphalt shingle (RAP/RAS) materials. Six commonly discussed intermediate temperature (cracking and durability) performance testing (i.e., Asphalt Mixture Performance Tester [AMPT] Cyclic Fatigue, Cantabro, Illinois Flexibility Index Test [I-FIT], Indirect Tensile Cracking [ITC, also known as IDEAL-CT], Indirect Tensile Nflex, and Texas Overlay Test) were selected for use in this study based on input from stakeholders. Test results were analyzed to compare differences between the cracking tests. In addition, statistical analyses were conducted to assess the separation among materials (lanes) for each performance test. Cyclic fatigue and IDEAL-CT tests showed the most promising results. The ranking from these two tests’ index parameters matched closely with ALF field performance. Furthermore, both showed reasonable variability of test data and they were successful in differentiating between different materials.

scholarly journals Cyclic fatigue resistance of 2Shape, Twisted File and EndoSequence Xpress nickel-titanium rotary files at intracanal temperature

2018 ◽  
Vol 12 (4) ◽  
pp. 283-287 ◽  
Author(s):  
Gülşah Uslu ◽  
Taha Özyürek ◽  
Mustafa Gündoğar ◽  
Koray Yılmaz
Keyword(s):  
Fatigue Resistance ◽  
Statistical Significance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Bonferroni Correction ◽  
Significant Difference ◽  
Inner Diameter ◽  
The Difference ◽  
Number Of Cycles ◽  
Analyze Data

Background. The aim of this study was to compare the cyclic fatigue resistance of 2Shape, Twisted File (TF) and EndoSequence Xpress (ESX) nickel-titanium rotary files at intracanal temperature (35°C). Methods. Twenty 2Shape TS1 (25/.04), 20 TF (25/.04) and 20 ESX (25/.04) files were tested for cyclic fatigue at intracanal temperature (35°C). All the instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 60° angle of curvature and a radius curvature of 5 mm until fracture occurred; the time to fracture was recorded in seconds using a digital chronometer and the number of cycles to fracture (NCF) for each file was calculated. Kruskal-Wallis test with Bonferroni correction was performed to statistically analyze data using SPSS 21.0. Statistical significance was set at P<0.05. Results. NCF values revealed that the 2Shape had significantly the highest cyclic fatigue resistance, followed by TF and ESX at intracanal temperature (P<0.05). The difference was significant between the TF and ESX groups (P<0.05). There was no significant difference among the 2Shape, TF and ESX files with respect to the lengths of the fractured file fragments (P>.05). Conclusion. Within the limitations of present study, it was concluded that the cyclic fatigue resistance of 2Shape files at the intracanal temperature is higher than that of TF and ESX files.

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