Fatigue Resistance of Engine-driven Rotary Nickel-Titanium Instruments Produced by New Manufacturing Methods (original) (raw)
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Cyclic Fatigue of Different Nickel-Titanium Rotary Instruments: A Comparative Study
The Open Dentistry Journal, 2009
Since the introduction of nickel-titanium alloy to endodontics, there have been many changes in instrument design, but no significant improvements in the raw material properties, or enhancements in the manufacturing process. Recently, a new method to produce nickel-titanium rotary (NTR) instruments has been developed, in an attempt to obtain instruments that are more flexible and resistant to fatigue. NTR instruments produced using the process of twisting (TF, SybronEndo, Orange, CA) were compared to NTR instruments from different manufacturers produced by a traditional grinding process. The aim of the study was to investigate whether cyclic fatigue resistance is increased for TF NTR files. Tests were performed with a cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (P< .05). In the mean number of cycles to failure when compared to the other tested 06-25 NTR. Hence, it can be concluded that size 06-25 TF NTR instruments were found to be significantly more resistant to fatigue than those produced with the traditional grinding process.
Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2010
Objective. This study examined the effect of the manufacturing methods (ground, electropolished, and twisted) and the cross-sectional area (CSA) of nickel-titanium (NiTi) rotary instruments on their cyclic fatigue resistance. Study design. A total of 80 NiTi rotary instruments (ISO 25/.06 taper) from 4 brands (K3, ProFile, RaCe, and TF) were rotated in a simulated root canal with pecking motion until fracture. The number of cycles to failure (NCF) was calculated. The CSA at 3 mm from the tip of new instruments of each brand was calculated. The correlation between the CSA and NCF was evaluated. All fractured surfaces were analyzed using a scanning electron microscope to determine the fracture mode. Results. The TF instruments were the most resistant to fatigue failure. The resistance to cyclic failure increased with decreasing CSA. All fractured surfaces showed the coexistence of ductile and brittle properties. Conclusion. The CSA had a significant effect on the fatigue resistance of NiTi rotary instruments. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:622-628) Supported by the 2008 SNUDH research fund (4-2008-0023). The first two authors contributed equally to this work.
An In Vitro Cyclic Fatigue Analysis of Different Endodontic Nickel-Titanium Rotary Instruments
Journal of Endodontics, 2012
Introduction: The study compared Twisted File (TF) with 3 traditionally manufactured systems to determine whether changes in the manufacturing process improved the cyclic fatigue resistance. Methods: Four rotary file systems, (1) ProFile (PF), (2) Mtwo, (3) K3, and (4) TF, were tested in artificial canals with 45 and 90 angles of curvature. Ten instruments each of the 4 file systems were tested in both angles of curvature (n = 10). All instruments had identical size and taper (.06/0.25 tip diameter). Results: A statistically significant difference (P < .05) was noted between TF and other nickel-titanium instruments in both 45 and 90 angles of curvature. TF showed the greatest mean number of cycles to failure. There was no statistical difference between PF and K3 (P > .05) in both canal curvatures; however, statistically significant difference (P < .05) was observed between Mtwo and the other 2 traditionally manufactured instruments. Mtwo showed the lowest mean number of cycles to failure. Conclusions: Under the conditions of this study, size .06/0.25 TF was significantly more resistant to fatigue than the other 3 instrument systems produced with the traditional grinding process.
Journal of Endodontics, 2011
Introduction: The aim of this study was to evaluate, by static and dynamic cyclic fatigue tests, the number of cycles to fracture (NCF) 2 types of rotary NiTi instruments: Twisted File (SybronEndo, Orange, CA), which is manufactured by a proprietary twisting process, and RaCe files (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which are manufactured by grinding. Methods: Twenty Twisted Files (TFs) and 20 RaCe files #25/.006 taper instruments were allowed to rotate freely in an artificial curved canal at 310 rpm in a static or a dynamic model until fracture occurred. Results: Measurements of the fractured fragments showed that fracture occurred at the point of maximum flexure in the midpoint of the curved segment. The NCF was significantly lower for RaCe instruments compared with TFs. The NCF was also lower for instruments subjected to the static test compared with the dynamic model in both groups. Scanning electron microscopic analysis revealed ductile morphologic characteristics on the fractured surfaces of all instruments and no plastic deformation in their helical shafts. Conclusions: Rotary NiTi endodontic instruments manufactured by twisting present greater resistance to cyclic fatigue compared with instruments manufactured by grinding. The fracture mode observed in all instruments was of the ductile type. (J Endod 2011;37:1553-1557
Cyclic fatigue resistance of four nickel-titanium rotary instruments: a comparative study
Annali di stomatologia, 2012
The aim of this study is to investigate cyclic fatigue resistance of four nickel - titanium rotary (NTR) instruments produced by a new method or traditional grinding processes. FOUR NTR INSTRUMENTS FROM DIFFERENT BRANDS WERE SELECTED: group 1. Twisted File produced by a new thermal treatment of nickel - titanium alloy; group 2. Revo S SU; group 3. Mtwo and group 4. BioRaCe BR3 produced by traditional grinding processes. A total of 80 instruments (20 for each group) were tested for cyclic fatigue resistance inside a curved artificial canal with a 60 degree angle of curvature and 5 mm radius of curvature. Time to fracture (TtF) from the start of the test until the moment of file breakage and the length of the fractured tip was recorded for each instrument. Means and standard deviations (SD) of TtF and fragment length were calculated. Data were subjected to one-way analysis of variance (ANOVA). Group 1 (Twisted File) showed the highest value of TtF means. Cyclic fatigue resistance of T...
Fatigue Resistance of Engine-Driven Rotary Nickel-Titanium Endodontic Instruments
Journal of Endodontics, 2002
A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.
2013
The aim of this study was to investigate whether cyclic fatigue resistance is increased for nickel titanium instruments manufactured with improved heating processes in clockwise or counterclockwise continuous rotation. The instruments compared were produced either using the R-phase heat treatment (K3XF; SybronEndo, Orange, CA, USA) or the M-wire alloy (ProFile Vortex; DENTSPLY Tulsa Dental Specialties, Tulsa, OK, USA). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments in curved artificial canals. Results indicated no significant difference in resistance to cyclic fatigue when rotary nickel titanium instruments are used in clockwise or counterclockwise continuous rotation. In both directions of rotation, size 04-25 K3XF showed a significant increase (P < 0.05) in the mean number of cycles to failure when compared with size 04-25 ProFile Vortex.
Cyclic fatigue of different nickel-titanium endodontic rotary instruments
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2006
A comparative study of the fatigue resistance of rotary nickel-titanium endodontic instruments was performed with the aim of assessing the influence of both instrument design and surface treatment on flexural fracture. Study design. To evaluate fatigue resistance of different rotary instruments, a total of 120 instruments were tested; these came from different sources: ProFile, RaCe, K3, Hero, and Mtwo. To compare the effect of electro-polishing procedures on fatigue resistance, a group of RaCe instruments (which are normally electro-polished) without surface treatment was used. A scanning electron microscope (SEM) study for each instrument was performed before and after fatigue study to determine the mode of fracture and the aspect of tips and cross-sectional surface areas. Results. ProFile instruments gave the best values for fatigue resistance. It was seen that for RaCe instruments the surface treatment reduces the presence of micro-cracks, surface debris, and machining damage.
A comparison of cyclic fatigue resistance in reciprocating and rotary nickel-titanium instruments
Australian Endodontic Journal, 2011
The cyclic fatigue resistance of four nickel-titanium endodontic instruments was compared. K3, ProFile and GT Series X rotary instruments were examined along with SafeSiders reciprocating instruments. 30/0.04 instruments at 25 mm length were compared. Cyclic fatigue testing was conducted by operating instruments in artificially constructed stainless steel canals with 30°and 45°angles of curvature and 5 mm and 7.5 mm radii of curvature. The time and cycles to failure were recorded for 192 samples. Statistical analysis was performed with three-way ANOVA and the Student-Neuman-Keuls multiple comparisons testing. With a 5 min maximum running time, no SafeSiders samples were observed to separate. ProFile and GT Series X instruments were found to be significantly more resistant than K3 instruments (P < 0.001) for all experiment groups. There was no statistical difference between ProFile and GT Series X files (P < 0.582).