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

  • Torsional Resistance of heat treated nickel titanium instruments under different temperature conditions
    Materials, 2021
    Co-Authors: Sang Won Kwak, Hyeon-cheol Kim, Sung Kyo Kim
    Abstract:

    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.

  • Torsional Resistance of waveone gold and reciproc blue according to the loading methods
    Journal of Endodontics, 2021
    Co-Authors: Sang Won Kwak, Ibrahim H Abutahun, Hyeon-cheol Kim
    Abstract:

    INTRODUCTION This study aimed to compare the Torsional Resistances and fracture modes of WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) using the repetitive Torsional loading (RTL) method and the conventional single-rotation (STL) method. METHODS A 3-mm file tip was fixed with a brass plate, and a Torsional load was applied using a custom device. In the RTL method, the file was driven counterclockwise at 50 rpm until it achieved the preset torque of 0.5 Ncm; thereafter, it was returned to its original position. This recovery of the file to its original position was defined as 1 Torsional loading cycle; the number of repetitive load cycles until fracture was counted. In the STL method, the files were rotated at a constant rate of 2 rpm in a counterclockwise direction until file fracture. The fragments fractured by the 2 methods were compared under a scanning electron microscope to examine the topographic features of the fractured surfaces and longitudinal aspects. RESULTS With the RTL method, Reciproc Blue showed a higher number of repetitive load cycles until fracture than WaveOne Gold (P < .05). With the STL method, Reciproc Blue also had a higher ultimate strength than WaveOne Gold (P < .05). Scanning electron microscopic findings of the fractured specimens from the 2 test methods showed different features of Torsional failure. CONCLUSIONS Within the study limitations, both the RTL and STL methods conferred similar Torsional Resistance. Therefore, the clinically relevant RTL method with repetitive and reciprocation motion can be used for testing Torsional Resistance.

  • effect of shaft length on the Torsional Resistance of rotary nickel titanium instruments
    Journal of Endodontics, 2020
    Co-Authors: Vasfiye Isik, Ibrahim H Abutahun, Sang Won Kwak, Mehmet Baybora Kayahan, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction This study was conducted to evaluate the effect of file length on the Torsional Resistance of nickel-titanium rotary files. Methods Forty-five new files with a #25 tip size and variable taper for ProTaper Next (PTN; Dentsply Sirona, York PA), ProTaper Gold (PTG, Dentsply Sirona), and HyFlex CM (HCM; Coltene-Whaledent, Allstetten, Switzerland) were divided into 3 subgroups (n = 15) according to the file length (21, 25, and 31 mm). Torsional tests were performed using a custom-made device (AEndoS; DMJ System, Busan, Korea). The maximum Torsional load and distortion angle were measured until file fracture occurred. The toughness was calculated using these data. All data were statistically analyzed using 2-way analysis of variance at a confidence level of 95%. One-way analysis of variance and Duncan post hoc comparison were also conducted to assess the difference among the independent variables, shaft length, and file system. Results A statistically significant interaction was observed between the file system and instrument length with respect to the maximum Torsional load (P Conclusions Within the limitations of this study, the instrument with a longer shaft may have higher maximum Torsional load or toughness than that with a shorter shaft.

  • effect from rotational speed on Torsional Resistance of the nickel titanium instruments
    Journal of Endodontics, 2017
    Co-Authors: Sang Won Kwak, Sung Kyo Kim, Asgeir Sigurdsson, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction The purpose of this study was to evaluate differences in Torsional Resistance using up-regulated speed of rotational spindle. Methods Three NiTi rotary instrument systems were selected in this study: K3XF (SybronEndo, Glendora, CA), BLX (B&L Biotech, Ansan, Korea), and OneShape (MicroMega, Besancon, France). The tip size and taper for all files were #25 and 0.06. Experimental groups ( n  = 10/group) were assigned to 2-, 60-, 350-, and 600-rpm groups by the rotational speed of spindle. Forty new files were used for each test. The file tip of 5-mm length was secured between brass plates. While keeping the file straight, it was rotated clockwise at a constant rotational speed until fracture occurred. The parameters of Torsional Resistance, Torsional load (Ncm), and distortion angle (°) were measured using an AEndoS- k (DMJ System, Busan, Korea), and the toughness until fracture was computed from these data. The 1-way analysis of variance test was used to analyze the Torsional Resistance at a significance level of 95%. All fractured fragments were observed under a scanning electron microscope to evaluate the topographic features of the fractured surfaces. Results No significant difference in Torsional Resistance was found among groups when they were compared for ultimate strength at the maximum torque, fracture angle, and toughness. Scanning electron microscopic examination of the fractured cross-sectional surfaces revealed typical features of Torsional fractures, concentric abrasion marks, and fibrous dimples from the Torsional center. Conclusions Under the conditions of the study, the Torsional Resistances of the rotary instruments were not affected by the rotational speed.

  • the effects of Torsional preloading on the Torsional Resistance of nickel titanium instruments
    Journal of Endodontics, 2017
    Co-Authors: Sang Won Kwak, Woocheol Lee, Shin Wook Ahn, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction This study evaluated the effect of Torsional preloading on the Torsional Resistance of nickel-titanium (NiTi) endodontic instruments. Methods WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper Universal F2 (Dentsply Maillefer) files were used. The ultimate Torsional strength until fracture was determined for each instrument. In the phase 1 experiment, the ProTaper and WaveOne files were loaded to have a maximum load from 2.0 up to 2.7 or 2.8 Ncm, respectively. In the phase 2 experiment, the number of repetitions of preloading for each file was increased from 50 to 200, whereas the preloading torque was fixed at 2.4 Ncm. Using Torsionally preloaded specimens from phase 1 and 2, the Torsional Resistances were calculated to determine the ultimate strength, distortion angle, and toughness. The results were analyzed using 1-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of 5 specimens per group were examined under a scanning electron microscope. Results All preloaded groups showed significantly higher ultimate strength than the unpreloaded groups (P  Conclusions Torsional preloading within the ultimate values could enhance the Torsional strength of NiTi instruments. The total energy until fracture was maintained constantly, regardless of the alloy type.

Sang Won Kwak - One of the best experts on this subject based on the ideXlab platform.

  • Torsional Resistance of heat treated nickel titanium instruments under different temperature conditions
    Materials, 2021
    Co-Authors: Sang Won Kwak, Hyeon-cheol Kim, Sung Kyo Kim
    Abstract:

    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.

  • Torsional Resistance of waveone gold and reciproc blue according to the loading methods
    Journal of Endodontics, 2021
    Co-Authors: Sang Won Kwak, Ibrahim H Abutahun, Hyeon-cheol Kim
    Abstract:

    INTRODUCTION This study aimed to compare the Torsional Resistances and fracture modes of WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) using the repetitive Torsional loading (RTL) method and the conventional single-rotation (STL) method. METHODS A 3-mm file tip was fixed with a brass plate, and a Torsional load was applied using a custom device. In the RTL method, the file was driven counterclockwise at 50 rpm until it achieved the preset torque of 0.5 Ncm; thereafter, it was returned to its original position. This recovery of the file to its original position was defined as 1 Torsional loading cycle; the number of repetitive load cycles until fracture was counted. In the STL method, the files were rotated at a constant rate of 2 rpm in a counterclockwise direction until file fracture. The fragments fractured by the 2 methods were compared under a scanning electron microscope to examine the topographic features of the fractured surfaces and longitudinal aspects. RESULTS With the RTL method, Reciproc Blue showed a higher number of repetitive load cycles until fracture than WaveOne Gold (P < .05). With the STL method, Reciproc Blue also had a higher ultimate strength than WaveOne Gold (P < .05). Scanning electron microscopic findings of the fractured specimens from the 2 test methods showed different features of Torsional failure. CONCLUSIONS Within the study limitations, both the RTL and STL methods conferred similar Torsional Resistance. Therefore, the clinically relevant RTL method with repetitive and reciprocation motion can be used for testing Torsional Resistance.

  • effect of shaft length on the Torsional Resistance of rotary nickel titanium instruments
    Journal of Endodontics, 2020
    Co-Authors: Vasfiye Isik, Ibrahim H Abutahun, Sang Won Kwak, Mehmet Baybora Kayahan, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction This study was conducted to evaluate the effect of file length on the Torsional Resistance of nickel-titanium rotary files. Methods Forty-five new files with a #25 tip size and variable taper for ProTaper Next (PTN; Dentsply Sirona, York PA), ProTaper Gold (PTG, Dentsply Sirona), and HyFlex CM (HCM; Coltene-Whaledent, Allstetten, Switzerland) were divided into 3 subgroups (n = 15) according to the file length (21, 25, and 31 mm). Torsional tests were performed using a custom-made device (AEndoS; DMJ System, Busan, Korea). The maximum Torsional load and distortion angle were measured until file fracture occurred. The toughness was calculated using these data. All data were statistically analyzed using 2-way analysis of variance at a confidence level of 95%. One-way analysis of variance and Duncan post hoc comparison were also conducted to assess the difference among the independent variables, shaft length, and file system. Results A statistically significant interaction was observed between the file system and instrument length with respect to the maximum Torsional load (P Conclusions Within the limitations of this study, the instrument with a longer shaft may have higher maximum Torsional load or toughness than that with a shorter shaft.

  • effect from rotational speed on Torsional Resistance of the nickel titanium instruments
    Journal of Endodontics, 2017
    Co-Authors: Sang Won Kwak, Sung Kyo Kim, Asgeir Sigurdsson, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction The purpose of this study was to evaluate differences in Torsional Resistance using up-regulated speed of rotational spindle. Methods Three NiTi rotary instrument systems were selected in this study: K3XF (SybronEndo, Glendora, CA), BLX (B&L Biotech, Ansan, Korea), and OneShape (MicroMega, Besancon, France). The tip size and taper for all files were #25 and 0.06. Experimental groups ( n  = 10/group) were assigned to 2-, 60-, 350-, and 600-rpm groups by the rotational speed of spindle. Forty new files were used for each test. The file tip of 5-mm length was secured between brass plates. While keeping the file straight, it was rotated clockwise at a constant rotational speed until fracture occurred. The parameters of Torsional Resistance, Torsional load (Ncm), and distortion angle (°) were measured using an AEndoS- k (DMJ System, Busan, Korea), and the toughness until fracture was computed from these data. The 1-way analysis of variance test was used to analyze the Torsional Resistance at a significance level of 95%. All fractured fragments were observed under a scanning electron microscope to evaluate the topographic features of the fractured surfaces. Results No significant difference in Torsional Resistance was found among groups when they were compared for ultimate strength at the maximum torque, fracture angle, and toughness. Scanning electron microscopic examination of the fractured cross-sectional surfaces revealed typical features of Torsional fractures, concentric abrasion marks, and fibrous dimples from the Torsional center. Conclusions Under the conditions of the study, the Torsional Resistances of the rotary instruments were not affected by the rotational speed.

  • the effects of Torsional preloading on the Torsional Resistance of nickel titanium instruments
    Journal of Endodontics, 2017
    Co-Authors: Sang Won Kwak, Woocheol Lee, Shin Wook Ahn, Hyeon-cheol Kim
    Abstract:

    Abstract Introduction This study evaluated the effect of Torsional preloading on the Torsional Resistance of nickel-titanium (NiTi) endodontic instruments. Methods WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper Universal F2 (Dentsply Maillefer) files were used. The ultimate Torsional strength until fracture was determined for each instrument. In the phase 1 experiment, the ProTaper and WaveOne files were loaded to have a maximum load from 2.0 up to 2.7 or 2.8 Ncm, respectively. In the phase 2 experiment, the number of repetitions of preloading for each file was increased from 50 to 200, whereas the preloading torque was fixed at 2.4 Ncm. Using Torsionally preloaded specimens from phase 1 and 2, the Torsional Resistances were calculated to determine the ultimate strength, distortion angle, and toughness. The results were analyzed using 1-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of 5 specimens per group were examined under a scanning electron microscope. Results All preloaded groups showed significantly higher ultimate strength than the unpreloaded groups (P  Conclusions Torsional preloading within the ultimate values could enhance the Torsional strength of NiTi instruments. The total energy until fracture was maintained constantly, regardless of the alloy type.

Victor Talarico Leal Vieira - One of the best experts on this subject based on the ideXlab platform.

  • effects of clinical use of niti reciprocating instruments on cyclic and Torsional Resistance and on roughness
    Brazilian Oral Research, 2021
    Co-Authors: Edson Jorge Lima Moreira, Victor Talarico Leal Vieira, Henrique Dos Santos Antunes, Daniele Moreira Cavalcante, Henrique Eduardo Oliveira, Diogo Da Silva Oliveira, Gustavo Dedeus, Emmanuel Joao Nogueira Leal Silva
    Abstract:

    The aim of the present study was to evaluate the cyclic fatigue, Torsional Resistance and surface roughness of Reciproc R25 instruments in four different situations, namely as new instruments and as instruments tested after clinical preparation of one, two or three maxillary molars with four root canals. The total time required to perform each root canal preparation was recorded. Cyclic fatigue Resistance was determined by the time to fracture using a customized testing device (n = 10 per group). The Torsional test evaluated the torque and angle of rotation to failure according to ISO 3630-1 (n = 10 per group). The roughness of the working parts of new and used instruments was evaluated with a profilometer (n = 5 per group). Statistical analysis was performed using one-way ANOVA and Tukey's test. The level of significance was set at 5%. No fractures or deformations were observed after clinical use. Higher preparation time was needed during the third use of the instruments for all root canals (p 0.05). Regarding the roughness measurements, groove depth was higher on new and one- versus two- or three-maxillary-molar-prepared instruments (p < 0.05). It can be concluded that the clinical use of Reciproc instruments increased preparation time and decreased surface roughness. However, clinical use did not affect the cyclic fatigue or Torsional Resistance of the Reciproc instruments.

  • bending buckling and Torsional Resistance of rotary and reciprocating glide path instruments
    International Endodontic Journal, 2020
    Co-Authors: Weber S P Lopes, Helio Pereira Lopes, Victor Talarico Leal Vieira, Emmanuel Joao Nogueira Leal Silva, M C D Silva, Flavio R F Alves, F R Pires
    Abstract:

    Aim To evaluate the bending, buckling and Torsional Resistance of ProGlider (PG) (Dentsply Sirona, Ballaigues, Switzerland), R-Pilot (RP) (VDW, Munich, Germany) and WaveOne Gold Glider (WOGG) (Dentsply Sirona). Methodology Ninety instruments were used: 30 PG (size 0.16, .02v taper), 30 RP (size 0.125, .04 taper) and 30 WOGG (size 0.15, .02v taper). The bending Resistance test was performed on 10 randomly selected instruments of each system according to ISO 3630-1 specifications. For the buckling Resistance test, a loading was applied in the axial direction of each instrument using a universal test machine, with a 20 N cell and 15 mm min-1 speed, in the axial direction. When a lateral elastic displacement of 1 mm occurred, the force was registered. The Torsional Resistance test was performed according to ISO 3630-1 specifications. Statistical analysis was performed using one-way anova and post hoc Student-Newman-Keuls test (P Results WOGG had the lowest bending Resistance, whilst RP had the highest bending Resistance (P 0.05). Conclusion The glide path instruments had different behaviours in term of bending, buckling and Torsional Resistance.

  • cyclic fatigue and Torsional Resistance of four martensite based nickel titanium reciprocating instruments
    European Endodontic Journal, 2020
    Co-Authors: Emmanuel Nogueira Da Silva, Victor Talarico Leal Vieira, C O De Lima, Henrique Dos Santos Antunes, Edson Jorge Lima Moreira, Marco Aurelio Versiani
    Abstract:

    OBJECTIVE To evaluate cyclic fatigue and Torsional Resistance of Reciproc Blue R25 (VDW, Munich, Germany), WaveOne Gold Primary (Dentsply Maillefer, Ballaigues, Switzerland), ProDesign R (Easy Equipamentos Odontologicos, Belo Horizonte, Brazil), and X1 Blue File (MK Life, Porto Alegre, Brazil) nickel titanium (NiTi) martensite reciprocating instruments. METHODS In each group, ten instruments were tested for cyclic fatigue Resistance using a stainless-steel artificial canal (curvature angle of 80° and radius of 3 mm) and ten instruments for Torsional failure according to ISO 3630-1 standard. The surface of the fractured instruments was examined under scanning electron microscopy (SEM) at ×250 magnification. The results were compared statistically with one-way ANOVA and post hoc Tukey tests and the alpha-type error was set at 5%. RESULTS X1 blue file and ProDesign Rinstruments showed highest time to fracture than Reciproc Blue and Wave One Gold (P 0.05). In addition, Reciproc Blue demonstrated highest time to fracture than WaveOne Gold (P<0.05). The lowest Torsional Resistance (1.0±0.2 N.cm) and angle of rotation (412o±46) was observed in the ProDesign R group (P<0.05). SEM analyses of fractured surfaces showed a crack initiation area and overload fast fracture zone after cyclic fatigue test, and concentric abrasion marks with microvoids at the centre of rotation after Torsional failure experiment. CONCLUSION Overall, X1 Blue File and ProDesign R showed higher cyclic fatigue Resistance than Reciproc Blue and WaveOne Gold instruments, while ProDesign R had the lowest Torsional Resistance and angular rotation values to fracture. SEM analysis of all instruments demonstrated typical failures features in both cyclic fatigue and Torsional failure tests.

  • influence of heat treatment on Torsional Resistance and surface roughness of nickel titanium instruments
    International Endodontic Journal, 2019
    Co-Authors: Emmanuel Joao Nogueira Leal Silva, Victor Talarico Leal Vieira, J F N Giraldes, C O De Lima, Carlos N Elias, Henrique Dos Santos Antunes
    Abstract:

    Aim To evaluate the influence of controlled memory (CM) thermal treatment on the Torsional Resistance and surface roughness of nickel-titanium instruments with identical geometric and dimensional characteristics. The influence of environmental temperature on Torsional Resistance was also evaluated. Methodology A sample of 25 conventional NiTi alloy and 25 CM thermal-treated NiTi instruments, with an identical geometric design and a nominal size of 0.25 mm at D0 and a nominal taper of .06 mm mm-1 were selected. The Torsional strength and the angle of rotation of the instruments were tested following ISO 3630-1 at two temperatures: 21 and 35 °C. The fracture surfaces of all tested instruments were verified with a scanning electron microscope. The surface roughness of the blades of conventional NiTi alloy and CM wire files was evaluated by using a New View 7100 Profilometer. Statistical analysis was performed using Student's t-test and paired t-test to analyse the Torsional Resistance and surface roughness at a significance level of P Results The Torsional strength of thermally-treated instruments was significantly lower than nontreated instruments (P 0.05) and the angular rotation (P > 0.05) of the instruments. Regarding the roughness measurements, groove depth was lower at the surface of thermally-treated instruments when compared to nontreated instruments (P Conclusion Thermal treatment influenced the Torsional Resistance and surface roughness of NiTi instruments with identical geometric and dimensional characteristics. Temperature did not affect Torsional behaviour.

  • Torsional fatigue Resistance of blue treated reciprocating instruments
    Journal of Endodontics, 2018
    Co-Authors: Emmanuel Joao Nogueira Leal Silva, Carlos N Elias, Henrique Dos Santos Antunes, Gustavo Dedeus, Fernanda Hecksher, Victor Talarico Leal Vieira
    Abstract:

    Abstract Introduction The aim of the present study was to evaluate the influence of blue thermal treatment on the Torsional Resistance behavior of M-Wire Reciproc files (VDW, Munich, Germany). Methods Ten M-Wire Reciproc R25 (25/0.08v) and 10 Reciproc Blue R25 (25/0.08v, VDW) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. Three millimeters of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Results were statistically analyzed using the Student t test at a significance level of P  Results The maximum Torsional strength of M-Wire Reciproc was higher than Reciproc Blue instruments (P  Conclusions Reciproc Blue instruments showed a higher angle of rotation to fracture but a lower torque to failure than M-Wire Reciproc instruments.

Emmanuel Joao Nogueira Leal Silva - One of the best experts on this subject based on the ideXlab platform.

  • effects of clinical use of niti reciprocating instruments on cyclic and Torsional Resistance and on roughness
    Brazilian Oral Research, 2021
    Co-Authors: Edson Jorge Lima Moreira, Victor Talarico Leal Vieira, Henrique Dos Santos Antunes, Daniele Moreira Cavalcante, Henrique Eduardo Oliveira, Diogo Da Silva Oliveira, Gustavo Dedeus, Emmanuel Joao Nogueira Leal Silva
    Abstract:

    The aim of the present study was to evaluate the cyclic fatigue, Torsional Resistance and surface roughness of Reciproc R25 instruments in four different situations, namely as new instruments and as instruments tested after clinical preparation of one, two or three maxillary molars with four root canals. The total time required to perform each root canal preparation was recorded. Cyclic fatigue Resistance was determined by the time to fracture using a customized testing device (n = 10 per group). The Torsional test evaluated the torque and angle of rotation to failure according to ISO 3630-1 (n = 10 per group). The roughness of the working parts of new and used instruments was evaluated with a profilometer (n = 5 per group). Statistical analysis was performed using one-way ANOVA and Tukey's test. The level of significance was set at 5%. No fractures or deformations were observed after clinical use. Higher preparation time was needed during the third use of the instruments for all root canals (p 0.05). Regarding the roughness measurements, groove depth was higher on new and one- versus two- or three-maxillary-molar-prepared instruments (p < 0.05). It can be concluded that the clinical use of Reciproc instruments increased preparation time and decreased surface roughness. However, clinical use did not affect the cyclic fatigue or Torsional Resistance of the Reciproc instruments.

  • bending buckling and Torsional Resistance of rotary and reciprocating glide path instruments
    International Endodontic Journal, 2020
    Co-Authors: Weber S P Lopes, Helio Pereira Lopes, Victor Talarico Leal Vieira, Emmanuel Joao Nogueira Leal Silva, M C D Silva, Flavio R F Alves, F R Pires
    Abstract:

    Aim To evaluate the bending, buckling and Torsional Resistance of ProGlider (PG) (Dentsply Sirona, Ballaigues, Switzerland), R-Pilot (RP) (VDW, Munich, Germany) and WaveOne Gold Glider (WOGG) (Dentsply Sirona). Methodology Ninety instruments were used: 30 PG (size 0.16, .02v taper), 30 RP (size 0.125, .04 taper) and 30 WOGG (size 0.15, .02v taper). The bending Resistance test was performed on 10 randomly selected instruments of each system according to ISO 3630-1 specifications. For the buckling Resistance test, a loading was applied in the axial direction of each instrument using a universal test machine, with a 20 N cell and 15 mm min-1 speed, in the axial direction. When a lateral elastic displacement of 1 mm occurred, the force was registered. The Torsional Resistance test was performed according to ISO 3630-1 specifications. Statistical analysis was performed using one-way anova and post hoc Student-Newman-Keuls test (P Results WOGG had the lowest bending Resistance, whilst RP had the highest bending Resistance (P 0.05). Conclusion The glide path instruments had different behaviours in term of bending, buckling and Torsional Resistance.

  • mechanical performance and metallurgical features of protaper universal and 6 replicalike systems
    Journal of Endodontics, 2020
    Co-Authors: Jorge N R Martins, Emmanuel Joao Nogueira Leal Silva, Duarte Marques, Mario Rito Pereira, Antonio Ginjeira, Rui J C Silva, Francisco Manuel Braz Fernandes, Marco Aurelio Versiani
    Abstract:

    Abstract Introduction This study aimed to compare the ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland) system with 6 replicalike instruments regarding instrument design, mechanical performance, and alloy characteristics. Methods New rotary instruments (size 20/.07v) of PTU and 6 replicalike systems (EdgeTaper [EdgeEndo, Johnson City, TN], U-File [Dentmark, Ludhiana, India], Go-Taper Universal [Access, Shenzhen, China], Super Files [Flydent, Shenzhen, China], Multitaper [Proclinic Expert, Besancon, France], and Pluri Taper [Bestdent, Shenzhen, China]) (n = 329) were selected and evaluated regarding their design, mechanical performance, and metallurgical characteristics. The results were compared using the nonparametric Mood median test and 1-way analysis of variance with the significance level set at 0.05. Results Replicalike instruments were similar to PTU regarding design, maximum torque to fracture (P > .05), and ratio of nickel and titanium elements. Scanning electron microscopy revealed differences in the geometry of the tip and finishing surfaces. Time to fracture of Go-Taper Universal (50.0 seconds) was similar to PTU (44.0 seconds) (P > .05), but the U-File (63.5 seconds), Edge Taper (87.5 seconds), and Super Files (130 seconds) showed significantly higher values (P .05). The angle of rotation before rupture of the Multitaper (574°) and Pluri Taper (481°) was higher than PTU (354°) (P Conclusions Overall, replicalike instruments were similar to PTU regarding the Torsional Resistance, geometric design, and near equiatomic proportions of nickel and titanium elements. In 3 of the 4 mechanical tests, the EdgeTaper (torque, angle of rotation, and bending load) and Go-Taper Universal (time to fracture, torque, and angle of rotation) systems were similar to PTU.

  • influence of heat treatment on Torsional Resistance and surface roughness of nickel titanium instruments
    International Endodontic Journal, 2019
    Co-Authors: Emmanuel Joao Nogueira Leal Silva, Victor Talarico Leal Vieira, J F N Giraldes, C O De Lima, Carlos N Elias, Henrique Dos Santos Antunes
    Abstract:

    Aim To evaluate the influence of controlled memory (CM) thermal treatment on the Torsional Resistance and surface roughness of nickel-titanium instruments with identical geometric and dimensional characteristics. The influence of environmental temperature on Torsional Resistance was also evaluated. Methodology A sample of 25 conventional NiTi alloy and 25 CM thermal-treated NiTi instruments, with an identical geometric design and a nominal size of 0.25 mm at D0 and a nominal taper of .06 mm mm-1 were selected. The Torsional strength and the angle of rotation of the instruments were tested following ISO 3630-1 at two temperatures: 21 and 35 °C. The fracture surfaces of all tested instruments were verified with a scanning electron microscope. The surface roughness of the blades of conventional NiTi alloy and CM wire files was evaluated by using a New View 7100 Profilometer. Statistical analysis was performed using Student's t-test and paired t-test to analyse the Torsional Resistance and surface roughness at a significance level of P Results The Torsional strength of thermally-treated instruments was significantly lower than nontreated instruments (P 0.05) and the angular rotation (P > 0.05) of the instruments. Regarding the roughness measurements, groove depth was lower at the surface of thermally-treated instruments when compared to nontreated instruments (P Conclusion Thermal treatment influenced the Torsional Resistance and surface roughness of NiTi instruments with identical geometric and dimensional characteristics. Temperature did not affect Torsional behaviour.

  • Torsional fatigue Resistance of blue treated reciprocating instruments
    Journal of Endodontics, 2018
    Co-Authors: Emmanuel Joao Nogueira Leal Silva, Carlos N Elias, Henrique Dos Santos Antunes, Gustavo Dedeus, Fernanda Hecksher, Victor Talarico Leal Vieira
    Abstract:

    Abstract Introduction The aim of the present study was to evaluate the influence of blue thermal treatment on the Torsional Resistance behavior of M-Wire Reciproc files (VDW, Munich, Germany). Methods Ten M-Wire Reciproc R25 (25/0.08v) and 10 Reciproc Blue R25 (25/0.08v, VDW) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. Three millimeters of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Results were statistically analyzed using the Student t test at a significance level of P  Results The maximum Torsional strength of M-Wire Reciproc was higher than Reciproc Blue instruments (P  Conclusions Reciproc Blue instruments showed a higher angle of rotation to fracture but a lower torque to failure than M-Wire Reciproc instruments.

Ove A Peters - One of the best experts on this subject based on the ideXlab platform.

  • an in vitro assessment of the physical properties of novel hyflex nickel titanium rotary instruments
    International Endodontic Journal, 2012
    Co-Authors: Ove A Peters, A K Gluskin, R A Weiss, J T Han
    Abstract:

    Peters OA, Gluskin AK, Weiss RA, Han JT. An in vitro assessment of the physical properties of novel Hyflex nickel–titanium rotary instruments. International Endodontic Journal, 45, 1027–1034, 2012. Abstract Aim  To determine several properties including Torsional and fatigue limits, as well as torque during canal preparation, of Hyflex, a rotary instrument manufactured from so-called controlled memory nickel–titanium alloy. Methodology  The instruments were tested in vitro using a special torque bench that permits both stationary torque tests according to ISO3630-1 and fatigue limit determination, as well as measurement of torque (in Ncm) and apical force (in N) during canal preparation. Fatigue limit (in numbers of cycles to failure) was determined in a 90°, 5 mm radius block-and-rod assembly. Simulated canals in plastic blocks were prepared using both a manufacturer-recommended single-length technique as well as a generic crown-down approach. anova with Bonferroni post hoc procedures was used for statistical analysis. Results  Torque at failure ranged from 0.47 to 1.38 Ncm, with significant differences between instrument sizes (P < 0.0001). Fatigue life ranged from 260 to 2565, with the shortest and longest lifespan for instruments size 20, .04 taper and size 25, .08 taper, respectively. Torque during canal preparation was significantly higher for small instruments used in the single-length technique but lower for the size 40, .04 taper, compared to a crown-down approach. No instrument fractured; 82% of the instruments used were plastically deformed; however, only 37% of these remained deformed after a sterilization cycle. Conclusions  Hyflex rotary instruments are bendable and flexible and have similar Torsional Resistance compared to instruments made of conventional NiTi. Fatigue Resistance is much higher, and torque during preparation is less, compared to other rotary instruments tested previously under similar conditions.

  • effect of immersion in sodium hypochlorite on torque and fatigue Resistance of nickel titanium instruments
    Journal of Endodontics, 2007
    Co-Authors: Ove A Peters, Jan O Roehlike, Michael Baumann
    Abstract:

    This study investigated the effect of immersion in sodium hypochlorite (NaOCl) on torque and fatigue Resistance of two nickel-titanium files. Size 25 .04 ProFile and RaCe files were immersed in 5.25% NaOCl for 1 or 2 hours at temperatures of 21°C and 60°C. Torque and angle at failure were measured according to ISO 3630-1. Resistance to cyclic fatigue was determined by counting rotations to breakage in a 90° curve with a 5-mm radius. Data were analyzed by 2-way analysis of variance. Torsional Resistance of both rotaries was not significantly affected by immersion in NaOCl, except after 2 hours of immersion at 60°C. Resistance to cyclic fatigue decreased significantly for ProFile and RaCe instruments after immersion in NaOCl. Spontaneous fractures occurred in 28 of 160 files during immersion in NaOCl. In conclusion, nickel-titanium rotaries have reduced Resistance to cyclic fatigue after contact with heated NaOCl and may then be considered single-use instruments.

  • effect of cyclic fatigue on static fracture loads in protaper nickel titanium rotary instruments
    Journal of Endodontics, 2005
    Co-Authors: Cheryl J Ullmann, Ove A Peters
    Abstract:

    The aim of the present study was to evaluate static fracture loads of ProTaper Nickel-Titanium instruments that had been subjected to various degrees of cyclic fatigue. Torque and angle at failure of new instruments and instruments that had been stressed to 30, 60, or 90% of their cyclic fatigue rotations in a simulated canal (90 degrees and 5 mm radius) were tested according to ISO 3630-1. With unused ProTaper instruments, Resistance to cyclic fatigue decreased with diameter increase and ranged from 158 to 450 rotations. Torque at failure ranged from 0.5 to 2.1 Ncm and showed a strong linear relationship to instrument diameter (r = 0.9) while angle at failure was weakly related to diameter (r = 0.46). Cyclic prestressing significantly reduced Torsional Resistance in finishing files, while shaping files were largely unaffected. In conclusion, build-up of tension within NiTi rotary instruments depends on instrument diameter. Clinically, larger instruments that have been subjected to some cyclic fatigue should be used with great care or discarded.

  • effect of cyclic fatigue on static fracture loads in protaper nickel titanium rotary instruments
    Journal of Endodontics, 2005
    Co-Authors: Cheryl J Ullmann, Ove A Peters
    Abstract:

    Abstract The aim of the present study was to evaluate static fracture loads of ProTaper Nickel-Titanium instruments that had been subjected to various degrees of cyclic fatigue. Torque and angle at failure of new instruments and instruments that had been stressed to 30, 60, or 90% of their cyclic fatigue rotations in a simulated canal (90° and 5 mm radius) were tested according to ISO 3630-1. With unused ProTaper instruments, Resistance to cyclic fatigue decreased with diameter increase and ranged from 158 to 450 rotations. Torque at failure ranged from 0.5 to 2.1 Ncm and showed a strong linear relationship to instrument diameter ( r 2 = 0.9) while angle at failure was weakly related to diameter ( r 2 = 0.46). Cyclic prestressing significantly reduced Torsional Resistance in finishing files, while shaping files were largely unaffected. In conclusion, build-up of tension within NiTi rotary instruments depends on instrument diameter. Clinically, larger instruments that have been subjected to some cyclic fatigue should be used with great care or discarded.