scholarly journals Advancement of Mechanical Properties of Nickel-Titanium Rotary Endodontic Instruments by Spring Machining on the File Shaft

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5246
Author(s):  
Sangmi Ahn ◽  
Jung-Hong Ha ◽  
Sang Won Kwak ◽  
Hyeon-Cheol Kim
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Significance Level ◽  
Rotary Instruments ◽  
Niti Instruments ◽  
General Dentists ◽  
Niti Rotary Instruments ◽  
Distortion Angle ◽  
Paired T Test

Nickel-titanium (NiTi) endodontic rotary instruments are used extensively in root canal procedures by both general dentists and specialists. However, their vulnerability to fracture is the major reason for clinicians’ concern regarding their use. The objective of this study was to investigate the potential effects of spring machining of the file shaft on the fatigue and torsional resistances of NiTi rotary instruments. Three types of NiTi rotary systems with (S) and without (NS) spring machining were used in this study (n = 15 each): a spring file (SPR; #25/.06, SPR-S, SPR-NS), a ProTaper Next X2 (PTN; #25/variable taper, PTN-S, PTN-NS), and a ProTaper Gold F2 (PTG; #25/variable taper, PTG-S, PTG-NS). Spring machining was adjusted on the 6 mm of each file system’s shaft via a laser cutting process. The number of rotation cycles until fracture (i.e., cyclic fatigue resistance), ultimate torsional strength, the distortion angle, and the toughness of each subgroup were estimated with specially designed devices. The results were analyzed using a paired t-test at a significance level of 95%. NiTi rotary instruments with spring machining exhibited a higher cyclic fatigue resistance than instruments without spring machining. The groups with spring machining exhibited a higher toughness and larger distortion angle than the groups without it (p < 0.05). In conclusion, spring machining on the shank of NiTi instruments may provide a stress-bearing area and attenuate the torsional and cyclic fatigue of NiTi rotary instruments.

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

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2523 ◽  
Author(s):  
Gianluca Gambarini ◽  
Gabriele Miccoli ◽  
Marco Seracchiani ◽  
Tatyana Khrenova ◽  
Orlando Donfrancesco ◽  
...  
Keyword(s):  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Segment Length ◽  
Flat Side ◽  
Heat Treated ◽  
Rotary Instruments ◽  
Time To Fracture ◽  
Niti Instruments ◽  
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.

scholarly journals Information regarding use of rotary nickel -titanium endodontic instruments among general dental practitioners: a questionnaire survey

2016 ◽  
Vol 4 (1) ◽  
pp. 4
Author(s):  
Ritu Meel ◽  
Deepak Raisingani ◽  
Ashwini Prasad ◽  
Rachit Mathur ◽  
Nidha Madan ◽  
...  
Keyword(s):  
Questionnaire Survey ◽  
Nickel Titanium ◽  
Cross Sectional ◽  
Rotary Instruments ◽  
Dental Practitioners ◽  
Instruments And Techniques ◽  
Niti Instruments ◽  
General Dentists ◽  
Niti Rotary Instruments

Aim: A cross-sectional questionnaire survey was conducted to obtain information on the use of rotary nickel –titanium endodontic instruments was conducted among General Dental Practioner A two sectioned questionnaire was mailed to 200 randomly general practioners to obtain information on usage of Nickel –Titanium endodontic instrument and data was collected.Results: Forty-six percent of the general practioners had used rotary NiTi instruments. 76% dentists use NiTi files for five or more times a week. Most of the dentist used NiTi file coronally &apically. General dentists experienced more file fracture at size 20 and 25 with 0.02 and 0.04 taper.Conclusions: Dentists are familiar with limitations of NiTi instruments and techniques. Current study showed the awareness of dentists about benefits of NiTi rotary instruments application comparing to traditional techniques and also the high percent usage of these instruments among general dentists.

scholarly journals Cyclic fatigue resistance of reduced-taper nickel-titanium (NiTi)instruments in doubled-curved (S-shaped) canals at body temperature

2020 ◽  
Vol 14 (2) ◽  
pp. 111-115 ◽  
Author(s):  
Gülsah Uslu ◽  
Mustafa Gündoğar ◽  
Taha Özyürek ◽  
Gianluca Plotino
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Clinical Environment ◽  
Root Canals ◽  
Rotary Instruments ◽  
Niti Instruments ◽  
Student’S T ◽  
Number Of Cycles

Background. This study was conducted to compare the cyclic fatigue resistance of VDW.ROTATE,TruNatomy Prime, HyFlex CM, and 2Shape nickel-titanium (NiTi) rotary instruments in doublecurvedcanals in a simulated clinical environment. Methods. Eighty NiTi files were used for the fatigue testing in stainless steel canals compatible withinstrument sizes until fracture occurred (n=20): VDW.ROTATE (04./25#), TruNatomy Prime (04./26#),HyFlex CM (04./25#) and 2Shape TS04./25#( 1). For each instrument, the number of cycles to fracture(NCF) was calculated, and the fractured fragment length (FL) was measured. To verify that the fileswere fractured due to cyclic fatigue, the fractured surfaces of the files were evaluated under a scanningelectron microscope. Data were statistically analyzed using the Kruskal–Wallis and Student’s t-tests atthe %95 confidence level. Results. The failure of the files due to cyclic fatigue was first seen in the apical curvature before thecoronal curvature (P<0.05). The highest fatigue resistance was observed in VDW.ROTATE and HyFlexCM files in both curvatures (P<0.05). There were no significant differences in the fatigue resistancebetween the HyFlex CM and VDW.ROTATE files or between the 2Shape and the TruNatomy files(P>0.05). There was no difference in the fractured lengths of the files between the apical and coronalcurvatures (P>0.05). Conclusion. In artificial S-shaped root canals, VDW.ROTATE and HyFlex CM files exhibited higherfatigue resistance compared to 2Shape and TruNatomy files.

scholarly journals Mechanical and Metallurgical Properties of Various Nickel-Titanium Rotary Instruments

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Kyu-Sang Shim ◽  
Soram Oh ◽  
KeeYeon Kum ◽  
Yu-Chan Kim ◽  
Kwang-Koo Jee ◽  
...  
Keyword(s):  
Angular Displacement ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Scanning Calorimetry ◽  
Metallurgical Properties ◽  
Rotary Instruments ◽  
Conventional Instrument ◽  
Conventional Alloy ◽  
Niti Instruments ◽  
Niti Rotary Instruments

The aim of this study was to investigate the effect of thermomechanical treatment on mechanical and metallurgical properties of nickel-titanium (NiTi) rotary instruments. Eight kinds of NiTi rotary instruments with sizes of ISO #25 were selected: ProFile, K3, and One Shape for the conventional alloy; ProTaper NEXT, Reciproc, and WaveOne for the M-wire alloy; HyFlex CM for the controlled memory- (CM-) wire; and TF for the R-phase alloy. Torsional fracture and cyclic fatigue fracture tests were performed. Products underwent a differential scanning calorimetry (DSC) analysis. The CM-wire and R-phase groups had the lowest elastic modulus, followed by the M-wire group. The maximum torque of the M-wire instrument was comparable to that of a conventional instrument, while those of the CM-wire and R-phase instruments were lower. The angular displacement at failure (ADF) for the CM-wire and R-phase instruments was higher than that of conventional instruments, and ADF of the M-wire instruments was lower. The cyclic fatigue resistance of the thermomechanically treated NiTi instruments was higher. DSC plots revealed that NiTi instruments made with the conventional alloy were primarily composed of austenite at room temperature; stable martensite and R-phase were found in thermomechanically treated instruments.

scholarly journals Torsional Resistance of Heat-Treated Nickel-Titanium Instruments under Different Temperature Conditions

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5295
Author(s):  
Hyo Jin Jo ◽  
Sang Won Kwak ◽  
Hyeon-Cheol Kim ◽  
Sung Kyo Kim ◽  
Jung-Hong Ha
Keyword(s):  
Nickel Titanium ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Temperature Conditions ◽  
Torsional Resistance ◽  
Heat Treated ◽  
Rotary Instruments ◽  
Single Use ◽  
Niti Instruments ◽  
Niti Rotary Instruments

This study compared the torsional resistance of heat-treated nickel-titanium (NiTi) instruments under different temperature conditions. Four thermomechanically treated single-use NiTi rotary instruments were selected for this study: OneShape (OS), OneCurve (OC), WaveOne Gold (WOG) and HyFlex EDM (HFE). Each instrument was further subdivided by temperature into 2 subgroups. Maximum torque and the distortion angle until fracture occurred were evaluated. Differential scanning calorimetry analysis was performed to measure the phase transformation temperature. Statistical analysis was performed using a two-way ANOVA and t-test (p < 0.05). Fractured fragments were observed using scanning electron microscopy (SEM). The two-way ANOVA showed no significant differences for different temperature conditions. At both room (RT) and body temperature (BT), OS was predominantly austenite while HFE was martensite. OC and WOG were predominantly martensite at RT and mixed phase at BT. At BT, more than half of WOG was martensite, while half of OC was austenite. SEM examination showed no topographical differences between instruments in different temperature groups. In relation to a limitation of this study, there was no difference in torsional resistance of NiTi rotary instruments between the BT and RT conditions. This implies that clinicians do not need to consider a decrease of torsional resistance of heat-treated NiTi instruments at BT.

scholarly journals Effect of Core Mass and Alloy on Cyclic Fatigue Resistance of Different Nickel-Titanium Endodontic Instruments in Matching Artificial Canals

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5734
Author(s):  
Sebastian Bürklein ◽  
Lennart Zupanc ◽  
David Donnermeyer ◽  
Karsten Tegtmeyer ◽  
Edgar Schäfer
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
The Other ◽  
Design Parameters ◽  
Core Mass ◽  
Cross Sectional ◽  
Significance Level ◽  
Cross Sectional Design ◽  
The Impact

Instrument failure during root canal preparation is still a concern among endodontists. However, it remains unclear whether the use of more martensitic alloys or the cross-sectional design parameters (i.e., core mass) significantly improve fracture resistance. The aim of the study was to evaluate the impact of core mass and alloy on dynamic cyclic fatigue resistance of nickel-titanium endodontic instruments in matching artificial canals at body temperature. Two groups were tested. (A) taper 0.04: F360 (Komet, Lemgo, Germany), Twisted file (Sybron Endo, Glendora, CA, USA) (=TF), JIZAI (Mani, Tochigi, Japan) (=J_04) (all size #25) and the variable tapered TruNatomy (Dentsply, Ballaigues, Switzerland) (size #26) (=TN). (B) size #25; taper 0.06: (Mtwo (VDW, Munich, Germany), JIZAI (Mani) (=J_06), and variable tapered Hyflex EDM OneFile (Coltene Whaledent, Altstätten, Switzerland) (=HF). Time, number of cycles to fracture (NCF), and number and length of fractured fragments were recorded and statistically analysed using ANOVA Student-Newman-Keuls, Kruskal–Wallis or Chi-square test (significance level = 0.05). (A) TN showed the significantly shortest time until fracture, followed by TF, F360 and J_04 which also differed significantly, while NCF showed the following order: F360 < TN < TF < J_04 (p < 0.05). Only one J_04 but all instruments of the other groups fractured within the test-limit of 10 min. (B) Mtwo was significantly inferior concerning time until fracture and NCF, compared to J_06 and HF (p < 0.05), which did not differ significantly (p > 0.05). While all Mtwo instruments fractured, only four instruments failed in the other groups (p < 0.05). Within the limitations of this study, alloy and cross-sectional design (i.e., core mass) were critical factors regarding instrument failure, but none of these factors could be determined as a main parameter for increased or decreased time, and cycles to fracture. Rather, it seemed to be the interaction of multiple factors (e.g., longitudinal and cross-sectional design, alloy, and rotational speed) that was responsible for differences in the time and cycles to fracture. Nonetheless, all instruments had lifetimes that allow safe clinical use. However, the superiority or inferiority of an instrument with regard to cyclic fatigue based on laboratory results—even when identical trajectories are guaranteed—may be considered questionable, as the characteristics and design parameters of the instruments vary considerably, and the experimental setups lack additional clinical parameters and thus clinical relevance.

scholarly journals Factors influencing incidents of complications while using nickel-titanium rotary instruments for root canal treatment

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Ahmad A. Madarati
Keyword(s):  
Root Canal ◽  
Nickel Titanium ◽  
Influential Factor ◽  
Common Complication ◽  
Pilot Studies ◽  
Significance Level ◽  
Rotary Instruments ◽  
Chi Squared ◽  
Final Questionnaire ◽  
General Dentists

Abstract Background To investigate the complications associated with the use of nickel titanium rotary instruments (NiTi-RIs) for root canal treatments (RCTs), in Saudi Arabia dental practice, and to explore the influencing factors. Methods After obtaining an ethical approval, two pilot studies were conducted to formulate the final questionnaire. The sample size was measured taking into consideration 60% expected response rates and confidence level of 99.9%. The questionnaire was emailed to 600 general dentists (GDs) randomly selected from the dental register and all of the endodontists (175). The email’s introduction clarified objectives of the study and guaranteed that all of the collected information would remain confidential. A reminder was sent after 10 weeks. The data were collected and analyzed using the chi-squared test at a 0.05 significance level. Results With a 51% overall response rate, 71.9% off the respondents used NiTi-RIs. The majority (83.1%) experienced complications while using NiTi-RIs; with the instruments’ fracture being significantly the most common complication (52.7%) (p < 0.001). The majority (87.7%) experienced NiTi-RIs’ fractureat least once; with more endodontists (94.3%) than GDs (83.3%) (p < 0.001). The greater the number of weekly performed RCTs and participants’ experiences, the more NiTi-RIs fractures and the greater the number of fracture incidents (p < 0.001). While 60% of those who performed 1–3 RCTs per week experienced NiTi-RIs fractures, 100% of those who performed more than 12 RCTs per week did so. The highest percentage of those who experienced more than 10 fractured NiTi-RIs (60%) was within the group who performed more than 12 RCTs per week. Although fracture incidents decreased with a smaller number of reuses, there was no significant correlation between the number of fractured instruments and NiTi-RIs discard strategy (p ≥ 0.05). Conclusion Fracture incidence was the most common complication while using NiTi-RIs, regardless of the clinicians’ experiences and skills. While the single use may reduce NiTi-RIs fractures, to some extent, the greater number of RCTs performed per week was the most influential factor.

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