NiTi Rotary Endodontic Instruments Research Articles

Endodontic Ni-Ti Rotary Instruments for Glide-path, Are They Still Necessary and How to Think about the Ideal Instrument?

How to cite this article: Reda R, Maccari E, Bhandi S. Endodontic Ni-Ti Rotary Instruments for Glide-path, Are They Still Necessary and How to Think about the Ideal Instrument? J Contemp Dent Pract 2024;25(6):505-506. Keywords: Alloy, Endodontics, Glide Path, NiTi Rotary Instruments, Patency.

New Indications Regarding the Use of Endodontic Ni-Ti Rotary Instruments, How Is Shaping Changing?

New Indications Regarding the Use of Endodontic Ni-Ti Rotary Instruments, How Is Shaping Changing?

Impact of endodontic irrigants on surface roughness of various nickel-titanium rotary endodontic instruments

BackgroundThe aim of the current study is to assess the surface roughness of several recent nickel-titanium (Ni-Ti) rotary endodontic instruments, namely: Protaper next (PTN); Hyflex CM (CM); Hyflex EDM (EDM); WaveOne gold (WOG); and trunatomy (TN), before and after application of 5.25% sodium hypochlorite (NaOCl) irrigant solution.MethodsIn this in vitro study, five recently introduced rotary endodontic instruments of different metallurgical properties and designs were subjected to Atomic Force Microscopy (AFM) analysis, and then each file was rotated in 5.25% NaOCl for 15 min., with speed and torque according to manufacturer’s instructions. The instruments were then subjected to AFM analysis again. The surface roughness average (Sa) parameter was calculated. Data were analyzed by Paired T test, One-way ANOVA and Tukey tests.ResultsThere was a statistically significant decrease in the surface roughness of all rotary endodontic instruments after immersion in irrigants (P ≤ 0.05).ConclusionThe new TN and PTN instruments showed the least surface roughness. All tested Ni-Ti rotary endodontic instruments after irrigants exposure showed a varying increase in surface roughness.

FEM analysis of NiTi rotary endodontic instruments to fatigue stress conditions: influence of geometrical parameters and design optimization

FEM analysis of NiTi rotary endodontic instruments to fatigue stress conditions: influence of geometrical parameters and design optimization

Are the Current Research Methods Reliable for Evaluating the Mechanical Performance of NiTi Endodontic Rotary Instruments?

Technological innovation and the modernization of manufacturing procedures have thoroughly redefined the field of nickel–titanium (NiTi) rotary and reciprocating endodontic instruments [...]

Influence of nickel-titanium rotary systems with varying cross-sectional, pitch, and rotational speed on deflection and cyclic fatigue: a finite element analysis study

The effectiveness of endodontic file preparation depends, among others, on the material, geometric shape, and the drive system. This study aimed to analyze the effect of cross-sectional, pitch, and rotational speed on cyclic fatigue and deflection of NiTi files using finite element analyses. A total of 18 NiTi endodontic rotary instruments ProTaper Gold F2 #25.08 and Hyflex CM #25.04 (n=9) modeling were designed using Autodesk software. Subjects were divided into two groups, the design group of square and convex triangles. Static simulation was then carried out to each group with force on the instrument’s tip by 1N, 2N, and 3N. The file’s cycling fatigue was analyzed at rotating speeds of 200 rpm, 300 rpm, and 400. The data were analyzed by using the three-way Analysis of variance (ANOVA) test followed by LSD (p< 0.05). The results showed the cross-sectional shape and force effect on the deflection value and cyclic fatigue received by the endodontic files (p< 0.05). The convex triangle design presented the lowest cyclic fatigue than square. The convex triangular cross-section design showed a higher deflection value than the square cross-section design.

The Effect of Multiple Autoclave Sterilization on the Cyclic Fatigue of Three Heat-Treated Nickel-Titanium Rotary Files: EdgeFile X7, Vortex Blue, and TRUShape

Objective The purpose of this study was to evaluate the effect of repeated autoclave sterilization on the cyclic fatigue resistance of heat-treated NiTi rotary endodontic instruments. Materials and Methods Three NiTi rotary endodontic instruments (EdgeFile X7, EFX7 0.30/0.4; Vortex Blue, VB 0.30/0.4; and TRUShape, TS 0.30/0.6) were selected. Each group (n = 24 each) was divided into 2 subgroups (n = 12 each): sterilized instruments and nonsterilized instruments. The sterilized instruments were subjected to 10 cycles of autoclave sterilization. Twelve instruments from each different subgroups were tested for cyclic fatigue resistance, and the number of cycles to failure (NCF) was calculated. Means and standard deviations were calculated for each group, and data were statistically analyzed using the SPSS program (P < 0.05). Results Sterilized and nonsterilized EFX7 files showed the highest NCF compared with other file subgroups. Comparing the results between sterilized and nonsterilized instruments for each type of files, there was a statistically significant difference (P < 0.05) only between sterilized and nonsterilized EFX7 files (1198 versus 755 NCF). The other instruments did not show significant differences (P > 0.05) in the mean NCF as a result of sterilization cycles (VB, 606 versus 568 NCF; TS, 487 versus 442 NCF). Conclusion Repeated cycles of autoclave sterilization increased the NCF of the new heat-treated files, with EFX7 showing statistically significant superior results compared with other files tested.

Experimental study of factors affecting the failure of the cyclical nature of rotary endodontic instruments

Relevance. The properties of shape memory, superelasticity and plasticity in nickel-titanium tools make the visual prediction of breakage as difficult as possible. Therefore, an important role is given to research, the purpose of which is to predict the time of their work and to identify the main factors affecting the probability of a fracture.Aim. Comparison of cyclic fatigue resistance of Ni-Ti rotary endodontic instruments of various manufacturers.Materials and methods. The influence of the autoclaving procedure and the angle of bending of the root canal on the resistance of a rotating endodontic instrument to cyclic loads was studied using an author's patented device that simulates the rotation of an instrument in a real channel; the number of cycles completed by each instrument before its fracture was recorded. The morphology of fractures, the microstructure of specimens under fractures, and the microhardness of specimens of endodontic instruments after testing were studied.Results. It has been established that resistance to fatigue fractures of instruments of various endodontic systems decreases with an increase in the bending angle of the root canal. For Endostar E3 Basic Rotary System tools, the number of cycles decreased by 1.2 times, for Protaper Universal tools by 2.9 times. The tools of the Protaper Next system reduced the number of cycles at a bending angle of the artificial root canal of 60 degrees by 1.5 times compared with the number of cycles at a bending angle of 45 degrees. At the same time, statistical data and the study of the microstructure of samples of new and past 6 cycles of autoclave tools did not show a connection between the autoclaving procedure and a decrease in their resistance to cyclic loads.Conclusions. When working in complex bent over 45 degrees channels, it is rational to choose an endodontic instrument that has undergone heat treatment at the production stage (in the framework of this study, it was Protaper Next 25/06 M-Wire alloy). This will reduce the likelihood of a file fracture and associated dangerous complications of endodontic treatment.

Endodontic Retreatment of a Mandibular Second Premolar with Four Roots and Four Canals: A Case Report

It is a well-recognised fact that incomplete cleaning, shaping and obturation of root canals will lead to endodontic failure. Mandibular second premolars usually have a single root and a single root canal. The presence of four separate roots and four root canals is quite rare. Hence, a comprehensive knowledge about the normal canal configuration along with its variations becomes an indispensable pre-requisite to achieve the success of endodontic treatment. Authors hereby present a case of a 26-year-old male patient and describe its succesful treatment of the mandibular second premolar with four roots and four root canals. The clinical implications of this paper aim at establishing an accurate diagnosis of the root canal system using diagnostic aids such as angulated radiographs and making use of advanced endodontic instruments for successful retreatment of endodontic therapy (C+ files and NiTi rotary endodontic instruments).

Role of the Flat-Designed Surface in Improving the Cyclic Fatigue Resistance of Endodontic NiTi Rotary Instruments.

The aim of this study was to investigate the role of the flat-designed surface in improving the resistance to cyclic fatigue by comparing heat-treated F-One (Fanta Dental, Shanghai, China) nickel–titanium (NiTi) rotary instruments and similar prototypes, differing only by the absence of the flat side. The null hypothesis was that there were no differences between the two tested instruments in terms of cyclic fatigue lifespan. A total of 40 new NiTi instruments (20 F-One and 20 prototypes) were tested in the present study. The instruments were rotated with the same speed (500 rpm) and torque (2 N) using an endodontic motor (Elements Motor, Kerr, Orange, CA, USA) in the same stainless steel, artificial canal (90° angle of curvature and 5 mm radius). A Wilcoxon–Mann–Whitney test was performed to assess the differences in terms of time to fracture and the length of the fractured segment between the flat- and non-flat-sided instruments. Significance was set at p = 0.05. The differences in terms of time to fracture between non-flat and flat were statistically significant (p < 0.001). In addition, the differences in terms of fractured segment length were statistically significant (p = 0.034). The results of this study highlight the importance of flat-sided design in increasing the cyclic fatigue lifespan of NiTi rotary instruments.

Microbial contamination of brand new nickel-titanium endodontic instruments.

This study aims to estimate the microbial presence on the surface of different brand new NiTi endodontic instruments for clinical use. Eleven different types of NiTi rotary endodontic instruments, obtained from their fresh opened original packages, were assigned to three different groups, according to packaging type and sterilization and tested for bacterial contamination. Isolated bacteria were identified by using standard microbiological methods and then counted. Differences observed in groups were analyzed statistically by using the one-way analysis of variance (ANOVA) for dependent samples and the Tukey HSD post hoc test. Statistical differences were found between instruments delivered in plastic boxes which bacterial count resulted higher than those obtained from instruments delivered in blisters (p<0.01). Some brand new endodontic instruments showed degrees of bacterial contamination that both quantitatively and qualitatively deserve to be considered in clinical procedures.

Cyclic fatigue resistance of M-Pro and RaCe Ni-Ti rotary endodontic instruments in artificial curved canals: a comparative in vitro study.

ObjectivesTo compare the flexural cyclic fatigue resistance and the length of the fractured segments (FLs) of recently introduced M-Pro rotary files with that of RaCe rotary files in curved canals and to evaluate the fracture surface by scanning electron microscopy (SEM).Materials and MethodsThirty-six endodontic files with the same tip size and taper (size 25, 0.06 taper) were used. The samples were classified into 2 groups (n = 18): the M-Pro group (M-Pro IMD) and the RaCe group (FKG). A custom-made simulated canal model was fabricated to evaluate the total number of cycles to failure and the FL. SEM was used to examine the fracture surfaces of the fragmented segments. The data were statistically analyzed and comparisons between the 2 groups for normally distributed numerical variables were carried out using the independent Student's t-test. A p value less than 0.05 was considered to indicate statistical significance.ResultsThe M-Pro group showed significantly higher resistance to flexural cyclic fatigue than the RaCe group (p < 0.05), but there was no significant difference in the FLs between the 2 groups (p ≥ 0.05).ConclusionsThermal treatment of nickel-titanium instruments can improve the flexural cyclic fatigue resistance of rotary endodontic files, and the M-Pro rotary system seems to be a promising rotary endodontic file.

Differences in cyclic fatigue lifespan between two different heat treated NiTi endodontic rotary instruments: WaveOne Gold vs EdgeOne Fire

BackgroundAim of this study is to investigate the cyclic fatigue resistance of the Gold treated WaveOne Gold and the Firewire treated EdgeOne Fire instruments. The null hypotesis was that there were no differences between the lifespan of Gold treated and FireWire treated instruments when subjected to cyclic fatigue tests.Material and Methods40 new NiTi instruments with a length of 25 mm were tested: 20 Wave One Gold Medium (WOG), tip size 35 and variable taper (Dentsply Maillefer, Ballaigues, Switzerland) and 20 Edge One Fire (EOF) (EdgeEndo, Albuquerque, New Mexico) tip size 35 and the same variable taper. A mobile support for the electric handpiece and a stainless-steel block containing the artificial canals were used. The same artificial root canal with a 90 degrees angle of curvature and 2 mm radius of curvature was used for all the tested instruments and the WOG counter-clock wise reciprocating motion with an engaging angle of 150° and a disengaging angle of 30° at 300 rpm, was selected for the test. All instruments were inserted at the same length (18mm) and then rotated in the same reciprocating motion until fracture occurred: the time was stopped as soon as the fracture was visible and video-recorded with a 1/100 sec chronometer. Differences among groups were statistically evaluated with an analysis of variance test ANOVA (significance level was set at p<0.05).ResultsMean values of time to fracture (TtF) for EOF instruments were 28,00 seconds (SD +/- 2,64) and for WOG instruments were 14,67 seconds (SD +/- 2,41). Statistical analysis found significant differences between the TtF of the two instruments (p<0,05).ConclusionsFirewire instruments resulted to be about two times more resistant to cyclic fatigue when compared with identical instruments made with Gold treatment. Key words:Endodontics, NiTi, Waveone Gold, EdgeOne Fire, Cyclic Fatigue.

Mechanism of fracture of NiTi superelastic endodontic rotary instruments.

The aim is to investigate the premature catastrophic fracture produced for different periods during clinical endodontic treatment of two brands of NiTi endodontic rotary instruments. 3 samples as-received, 6 samples used with patients for 2 and 7 h and 5 samples fractured were studied for each brand of endodontic NiTi rotary instruments. Transformation temperatures (Ms, Mf, As and Af) and enthalpies of transformation were determined by calorimetry. Critical stresses until fracture (σβ→SIM, σSIM→β) were obtained using an electromechanical testing machine. The samples were also visualized by Scanning Electron Microscopy. Calorimetric studies have shown an increase of the Ms and As transformation temperatures with time of use as well as a decrease of their stress transformations. Moreover, reverse transformation enthalpies decreased along the time. The enthalpies of transformation decreased because martensitic plates were anchored, which prevented their transformation to austenite; thus losing its superelastic effect. The stabilisation of the martensitic plates induced the collapse of the structure and so the main cause for the fracture. The heat treatment proposed has been increased the life in service of NiTi superelastic endodontic instruments recovering theirs superelastic effect.

Periodontal health in children with diabetes mellitus type 1 in Montenegro

Summary Introduction Separation of instruments in the root canal is one of the challenges in endodontic treatment. More specifically, nickel-titanium (NiTi) rotary instruments usually separate without previous deformation. The aim of this pilot study was to assess the effect of torsional stress on endodontic NiTi rotary instruments separation in simulated clinical conditions. Materials and methods Research was conducted on a sample of 20 human teeth in laboratory conditions. Experimental procedure consisted of determining canal curvatures for each root on digital radiographs and root canal treatment using endodontic NiTi rotary instruments. Out of 20 teeth (60 canals), two groups were formed with similar root canal curvatures (10 pairs of teeth) and instrumented using NiTi rotary instrument with or without torque control. Results Wilcoxon matched pair test showed no statistically significant difference in average number of instruments use with or without torque control (p&gt;0.05). Conclusion Even though there is no statistical significance in instrument separation when instruments were used with or without torque, there is tendency to experience sudden fracture of instruments after work without torsional control even after only few uses in clinical work.

Deformation of Nickel-Titanium (NiTi) rotary instruments in cyclic loading – in vitro study

Summary Introduction Separation of instruments in the root canal is one of the challenges in endodontic treatment. More specifically, nickel-titanium (NiTi) rotary instruments usually separate without previous deformation. The aim of this pilot study was to assess the effect of torsional stress on endodontic NiTi rotary instruments separation in simulated clinical conditions. Materials and methods Research was conducted on a sample of 20 human teeth in laboratory conditions. Experimental procedure consisted of determining canal curvatures for each root on digital radiographs and root canal treatment using endodontic NiTi rotary instruments. Out of 20 teeth (60 canals), two groups were formed with similar root canal curvatures (10 pairs of teeth) and instrumented using NiTi rotary instrument with or without torque control. Results Wilcoxon matched pair test showed no statistically significant difference in average number of instruments use with or without torque control (p&gt;0.05). Conclusion Even though there is no statistical significance in instrument separation when instruments were used with or without torque, there is tendency to experience sudden fracture of instruments after work without torsional control even after only few uses in clinical work.

A comparative Study to Evaluate the Effect of Sodium hypochlorite Temperature on Cyclic Fatigue Resistance of Three Types of Rotary Instrument

Background: The fracture of instruments within root canal during endodontictreatment is a common incidence, fracture of fatigue through flexure occursbecause of metal fatigue, NaOCl used for irrigation may have an effect oncorrosion that decrease fracture resistance. This study aimed to assess the effect ofNaOCl temperature on the cyclic fatigue of different type of Endodontic NiTiRotary Instruments and compare among them.Materials and method: three types of rotary instruments with tip size 0.25: ProTaPerF2 (Densply,Malifier) Revo-S SU ( 0.06 taper, MicroMega) and RaCe system(0.06 taper, FKG,Dentaire), Thirty file of each instrument type were used withincanal with 60° angle of curvature , undiluted NaOCl (5.25% ) were used. Ten filewithout immersion in NaOCl, ten were immersed at room temperature (21°C) for5 minute and ten with immersion in NaOCl at 60°C for the same time. Nine groupwere formed for all instruments (total number=90). The testing canal customizedwithin stainless steel block covered with glass face, the time to fracture recordedand the mean of cycles to fracture (MCF) detected for each instrument .Data wereanalyzed statistically by ANOVA, LSD and Independent T-test at 5% significantlevel.Result: there was a highly significant difference in mean of cycles to fracture for eachrotary instrument when temperature of NaOCl increased that the Number of cyclesto fracture decreased as the temperature increased. RaCe revealed the best fractureresistance followed by ProTaper then Revo-s that showed the less resistance.Conclusion: the rotary instruments more prone to fracture when temperature ofNaOCl increased, as well as the rotary instruments differ from each otheraccording to manufacturing process, taper, cross section and other factors.

Current Strategies in Metallurgical Advances of Rotary NiTi Instruments: A Review

Endodontic instruments made of NiTi shape memory alloy have had a revolutionary impact on root canal treatment This development has fostered a significant amount of research that is focused on enhancing metallic properties to improve clinical performance and safety which will significantly affect the outcome of root canal shaping and cleaning The mechanical properties of nickel titanium NiTi instruments are influenced by factors such as cross section flute design raw material and manufacturing processes The integration of surface engineering implantation or electropolishing and or microstructure control heat treatment or innovative manufacturing techniques into the endodontic file design has resulted in more favorable outcomes for instrument flexibility fatigue resistance and cutting efficiency This review will address the modifications in the metallurgy of the contemporary endodontic NiTi rotary instruments

Influence of an Innovative Anti-Corrosive Solution on Resistance of Endodontic NiTi Rotary Instruments: A Preliminary Study.

Objective:To evaluate the effects of deionised water, blood, phosphate-buffered saline (PBS) and a new anti-corrosive solution based on methoxy propyl amine (MOPA) on the cyclic fatigue resistance of endodontic NiTi rotary instruments under in vitro conditions.Methods:Forty ProTaper F1 files were provided and divided to four groups (n=10). Samples were first autoclaved and then stored in deionised water, blood, PBS or MOPA for 24 hours. Cyclic fatigue was tested with a custom-made stainless-steel block including artificial canals (curvature angle=30 degree, radius of curvature=5 mm). After immersion in test solutions, samples were rotated 300 rpm until fracture occurred. The number of cycles to failure (NCF) was calculated using recorded fracture time.Results:Data were analysed by the Kolmogorov–Smirnov, Levene, ANOVA and Scheffe statistical tests. Samples in blood group showed the lowest and samples in MOPA group showed the highest NCF values. Significant difference was observed between groups (P=0.001). NCF value of PBS group was significantly more than the NCF values of samples in blood and deionised water groups (P<0.05).Conclusion:The tested novel anti-corrosive solution significantly increased the fracture resistance of the endodontic NiTi rotary instruments by reducing the cyclic fatigue. In contrast, blood and deionised water caused more corrosion and resulted in earlier file fracture.

A new torquemeter to measure the influence of heat-treatment on torsional resistance of NiTi endodontic instruments

Abstract NiTi endodontic rotary instruments have increased flexibility and strength compared with stainless steel instruments, but they seem to be vulnerable to fracture in clinical situations. Heat treatment (thermal processing) is one of the most fundamental approaches toward adjusting the transition temperatures of NiTi alloys and affecting the fatigue and torsional resistance of NiTi endodontic files. In recent years, novel thermo-mechanical processing and manufacturing technologies such as controlled memory wire (CM-wire), M-Wire and electrical discharge machining (EDM) have been developed to optimize the microstructure of NiTi alloys and their mechanical properties. Aim of this work was to investigate the torsional resistance (maximum torque load, and angular rotation) of NiTi instruments made by different thermo-mechanical and manufacturing processes. For this purpose, a torque device able to perform static and dynamic tests of Ni-Ti instruments for root canal treatment was designed and realized, by performing this device through the design and optimization of the single components and on the system globally.