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U P Nair - One of the best experts on this subject based on the ideXlab platform.

  • fractographic analysis of separated Endodontic File designs
    Journal of Materials Science: Materials in Medicine, 2020
    Co-Authors: J J Mecholsky, A A Barrett, C T Jones, K M Pace, U P Nair
    Abstract:

    Endodontic rotary Files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of File separation failure. This research employed controlled, dynamic testing to failure of commercial rotary Files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three File designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277-EE; 899-VB; 713-PI) demonstrated significant statistical differences among groups (p < 0.001). Separated apical fragments yielded statistically significant differences (p ≤ 0.05) for varying File design groups. Weibull moduli among groups were statistically equivalent. Fractographic analysis exposed a presence of multiple failure factors in addition to defect distribution, governing cyclic fatigue failure originating at stress concentration points irrespective of File design. Fractographic analysis indicated that a change in File design, specifically at the working edges, in addition to improved surface finish, has the potential of reducing failures by lowering points of stress concentration and reducing fracture initiating surface cracks.

  • Fractographic analysis of separated Endodontic File designs
    Journal of Materials Science: Materials in Medicine, 2020
    Co-Authors: J J Mecholsky, A A Barrett, C T Jones, K M Pace, U P Nair
    Abstract:

    Endodontic rotary Files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of File separation failure. This research employed controlled, dynamic testing to failure of commercial rotary Files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three File designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277—EE; 899—VB; 713—PI) demonstrated significant statistical differences among groups ( p  

Hyeoncheol Kim - One of the best experts on this subject based on the ideXlab platform.

  • torsional behavior of waveone gold Endodontic File with the dedicated motor of the original waveone File
    Materials, 2018
    Co-Authors: Asgeir Sigurdsson, Gustavo Dedeus, Antheunis Versluis, Sang Won Kwak, Hyeoncheol Kim
    Abstract:

    This study compares the safety limits and torsional resistances of WaveOne Gold (WOG) and WaveOne (WO) Endodontic Files while using the original motor. The safety limits for reciprocating angles were tested by measuring the torsional limit before plastic deformation (TLP) after repetitive torsional loading at gradually increasing load, and after single continuous rotation. Statistical analysis was performed by independent t-test at 95% confidence level. The tested specimens were observed under a scanning electron microscope (SEM). Regardless of the test mode, the distortion angle at the TLP was higher for WOG than WO (p < 0.05), and all were greater than the 150-degree rotation of the original motor. The mean values of the distortion angle and torque from the single continuous rotation loading were significantly lower than those with repetitive loading movements. Comparing the two systems under SEM, WO showed a catastrophic change in comparison with WOG. Evaluation of the lateral aspects showed longitudinal micro-cracks after 270-degree repetitive movements. After 150-degree repetitive movements, no distorted machining grooves were found in either group, but WO showed evidence of longitudinal micro-cracks. Under the conditions of this study, the torsional loading from the pre-set mode of the dedicated motor for WO was safe for WOG as well.

  • vibrations generated by several nickel titanium Endodontic File systems during canal shaping in an ex vivo model
    Journal of Endodontics, 2017
    Co-Authors: Dongmin Choi, Sang Won Kwak, Jinwoo Kim, Sehee Park, Kyungmo Cho, Hyeoncheol Kim
    Abstract:

    Abstract Introduction This study aimed to compare the vibration generated by several nickel-titanium (NiTi) File systems and transmitted to teeth under 2 different motions (continuous rotation motion and reciprocating motion). Methods Sixty J-shaped resin blocks (Endo Training Bloc-J; Dentsply Maillefer, Ballaigues, Switzerland) were trimmed to a root-shaped form and divided into 2 groups according to the types of electric motors: WaveOne motor (WOM, Dentsply Maillefer) and X-Smart Plus motor (XSM, Dentsply Maillefer). Each group was further subdivided into 3 subgroups (n = 10 each) according to the designated File systems: ProTaper Next (PTN, Dentsply Maillefer), ProTaper Universal (PTU, Dentsply Maillefer), and WaveOne (WOP, Dentsply Maillefer) systems. Vibration was measured during the pecking motion using an accelerometer attached to a predetermined consistent position. The average vibration values were subjected to 2-way analysis of variance as well as the t test and Duncan test for post hoc comparison at the 95% confidence interval. Results Both motor types and instrument types produced significantly different ranges of average vibrations. Regardless of the instrument types, the WOM group generated greater vibration than the XSM group (P  Conclusions Under the limitations of this study design, the reciprocating NiTi File system may generate greater vibration than the continuous rotation NiTi File systems. The motor type also has a significant effect to amplify the vibrations.

Van T Himel - One of the best experts on this subject based on the ideXlab platform.

  • shaping ability of three nickel titanium Endodontic File systems in simulated s shaped root canals
    Journal of Endodontics, 2012
    Co-Authors: Jeffrey R Burroughs, Brian E Bergeron, Mark D Roberts, Joseph L Hagan, Van T Himel
    Abstract:

    Abstract Introduction The purpose of this study was to determine the shaping ability of 3 nickel-titanium (NiTi) Endodontic File systems by measuring canal transportation. Methods Seventy-two S-shaped canals in resin blocks were randomly allocated into 3 groups ( n  = 24): the Self-Adjusting File (SAF; ReDent Nova, Ra’anana, Israel) group, the Typhoon group (Typhoon rotary Files with Controlled Memory Wire; DS Dental, Johnson City, TN), and the Vortex group (ProFile Vortex rotary Files with M-Wire NiTi; Dentsply Tulsa Dental Specialties, Tulsa, OK). Blocks were secured in a jig for imaging standardization and instrumentation stabilization. Gates Glidden and PathFile drills (25 mm/.02 taper) were used to prepare the glide paths. For the Typhoon and Vortex groups (25 mm/.04 taper), canals were flooded with sterile water and instrumented using a crown-down technique from sizes 40 to 20/.04 and then apically enlarged to size 30/.04. The SAF group (25 mm) was instrumented with constant sterile water irrigation in a light-pecking, transline motion. Pre- and postinstrumentation images were taken at 40× magnification and layered, and canal transportation was measured. Results After adjusting for the level and canal wall side, the mean transportation was significantly higher for the Typhoon ( P P  = .005) groups compared with the SAF group. Additionally, the mean transportation was significantly higher for the Typhoon group versus the Vortex group ( P Conclusions Under the conditions of this study, SAFs showed less canal transportation than ProFile Vortex and Typhoon Files in simulated S-shaped root canals.

  • comparison of autoclaving effects on torsional deformation and fracture resistance of three innovative Endodontic File systems
    Journal of Endodontics, 2011
    Co-Authors: Rhett B Casper, Van T Himel, Mark D Roberts, Howard W Roberts, Brian E Bergeron
    Abstract:

    Abstract Introduction Recent innovative manufacturing techniques have produced nickel-titanium (NiTi) rotary instruments with reports of superior properties compared with standard NiTi Files. These include ProFile Vortex made from M-Wire (PV), Twisted Files (TF), and 10 Series Files made from CM Wire (CM). Sterilization is recommended before use and is repeated if Files are reused and/or carried forward between cases. The purpose for this study was to compare the effects of multiple autoclaving cycles on the torsional load resistance of these 3 new rotary Endodontic Files. Methods PV, TF, and CM Files (n = 100; size 25/.04) were divided into 5 groups (n = 20). Files were steam autoclaved for 1, 2, 3, and 7 sterilization cycles. A control group was not subjected to autoclaving. Files were tested in a torsiometer in general accordance with ISO 3630-1 standards. Torsional load and degrees of rotation to failure were recorded. Mean data were analyzed by using Kruskal-Wallace/Dunn post hoc tests ( P Results Autoclave cycles had no significant overall effect on File performance for any of the instrument systems tested. PV and CM displayed significantly greater resistance to torsional load than TF ( P P > .05). Angular deflection values for TF and CM were significantly higher than for PV ( P P Conclusions Under the conditions of this study, repeated steam autoclaving did not affect torsional resistance for unused Files of the systems evaluated. In addition, CM Wire Files might have a combined advantage of greater torsional strength and high deformation before failure.

R. Arbab Chirani - One of the best experts on this subject based on the ideXlab platform.

  • experimental validation of numerical simulations of a new generation niti Endodontic File under bending
    Journal of Materials Engineering and Performance, 2018
    Co-Authors: Laurent Pino, Sylvain Calloch, Valérie Chevalier, R. Arbab Chirani, S. Arbab Chirani
    Abstract:

    The superelasticity of NiTi shape memory alloy has been used in Endodontics since the 1990s. To study the mechanical behavior of Endodontic instruments, a traditional approach consists in experimental investigations. However, finite element analysis constitutes another way to assess their mechanical behavior and to facilitate their design. The main aim of this study is to compare experimental and numerical bending results on different structures (NiTi wire, spreader, and instruments) to estimate the reliability of the finite element simulations. These investigations were carried out as follows. Firstly, experimental material parameters identification was performed using NiTi wires. These parameters were implemented in an appropriate NiTi model. Bending was numerically applied to the meshed structures generated by the finite element method. Experimental tests were performed on real structures under bending, with exactly the same loading, in order to compare experimental and numerical results. These results were in good agreement for each of the considered structures. This enabled the validation of the simulation results and the use of simulations to design new Endodontic instruments.

  • Mechanical Behavior of a NiTi Endodontic File During Insertion in an Anatomic Root Canal Using Numerical Simulations
    Journal of Materials Engineering and Performance, 2015
    Co-Authors: Vincent Legrand, S. Moyne, Laurent Pino, S. Arbab Chirani, Sylvain Calloch, Valérie Chevalier, R. Arbab Chirani
    Abstract:

    Superelastic NiTi shape memory alloys (SMA) have biomedical applications including rotary Endodontic Files. These alloys are used thanks to their flexibility, which is due to solid-solid martensitic transformation. Unfortunately, the intracanal File separation can occur during canal preparation. To avoid this problem and to have a good idea of the mechanical behavior of these instruments, finite elements simulations taking into account the real shape of root canals are proposed in this study. This is possible by using a well-adapted model describing all the particularities of SMA and representative limit conditions. The behavior model has been validated in previous studies under complex loadings. It is implemented in ABAQUS® finite elements software. The anatomic shapes of root canals are extracted by microtomography using a real tooth. They are applied as limit conditions in realized simulations to be as near as possible to clinical conditions. The mechanical behavior of an Endodontic File is then simulated during insertion in a root canal without and with rotation. This permits to obtain different information like the loading applied to the instrument during its use, the stress, and the phase transformation fields through the File. This is useful not only for clinical use but also for new NiTi Endodontic instruments design.

J J Mecholsky - One of the best experts on this subject based on the ideXlab platform.

  • fractographic analysis of separated Endodontic File designs
    Journal of Materials Science: Materials in Medicine, 2020
    Co-Authors: J J Mecholsky, A A Barrett, C T Jones, K M Pace, U P Nair
    Abstract:

    Endodontic rotary Files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of File separation failure. This research employed controlled, dynamic testing to failure of commercial rotary Files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three File designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277-EE; 899-VB; 713-PI) demonstrated significant statistical differences among groups (p < 0.001). Separated apical fragments yielded statistically significant differences (p ≤ 0.05) for varying File design groups. Weibull moduli among groups were statistically equivalent. Fractographic analysis exposed a presence of multiple failure factors in addition to defect distribution, governing cyclic fatigue failure originating at stress concentration points irrespective of File design. Fractographic analysis indicated that a change in File design, specifically at the working edges, in addition to improved surface finish, has the potential of reducing failures by lowering points of stress concentration and reducing fracture initiating surface cracks.

  • Fractographic analysis of separated Endodontic File designs
    Journal of Materials Science: Materials in Medicine, 2020
    Co-Authors: J J Mecholsky, A A Barrett, C T Jones, K M Pace, U P Nair
    Abstract:

    Endodontic rotary Files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of File separation failure. This research employed controlled, dynamic testing to failure of commercial rotary Files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three File designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277—EE; 899—VB; 713—PI) demonstrated significant statistical differences among groups ( p