Research that matters: studies on fatigue of rotary and reciprocating NiTi root canal instruments

Hülsmann, Michael

doi:10.1111/iej.13194

Cited by 21 publications

(12 citation statements)

References 15 publications

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“…Nickel-titanium rotary instrumentation has gained wide popularity in the endodontic community over the past decades (Bird et al 2009). Whilst there are numerous studies dealing with forces acting on motorized endodontic instruments (Hülsmann 2019), there is little information on the forces these instruments exert on the canal walls and roots (Gambarini et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Effect of dentine cutting efficiency on the lateral force created by torque‐controlled rotary instruments

2020

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AIM To study the impact of dentine cutting efficiency of rotary instruments on the lateral force they create when instrumenting simulated root canals in bovine dentine. METHODOLOGY Lateral cutting efficiency of austenitic files (ProTaper Universal) was compared to that of counterparts of a reported identical geometrical design with a martensite phase component (ProTaper Gold) in bovine dentine disks (n = 6). Instrument shapes were studied using digital microscopy. The intracanal lateral force exerted by the two systems in simulated premolars (n = 9) made from bovine incisor roots containing a standardized narrow root canal of 16 mm length was monitored using a testing apparatus equipped with a torque-controlled endodontic motor/handpiece. Data were compared using parametric statistics, alpha error = 0.05. RESULTS The geometrical design of the two systems under investigation was found to be identical. The martensitic nickel-titanium rotary files had a significantly (t-test, P < 0.05) higher lateral cutting efficiency than austenitic counterparts. This difference, however, did not impact the lateral force that was created when instrumenting simulated premolar root canals. Furthermore, lateral force peaks were generated with the progressively tapered instruments under investigation towards the full working length. Even though a glide path was prepared, the first instrument in the full-length sequence (S1) created the highest lateral force (anova/Tukey's HSD, P < 0.05). CONCLUSIONS The current experimental set-up allows the study of the lateral force generated during root canal instrumentation. This force was not influenced by the dentine cutting efficiency of the instruments under investigation, but rather by their geometrical design.

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Section: Introductionmentioning

confidence: 99%

Effect of dentine cutting efficiency on the lateral force created by torque‐controlled rotary instruments

2020

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“…Recent studies have convincingly demonstrated a higher CF resistance of instruments with new alloys and designs; however, low-cost instruments are being incorporated to the market and a lower reliability has been reported to be expected when using such offerings (12,22). We suggest that minimum criterion be implemented for manufacturers to demonstrate the reliable use of new instruments in clinical settings, before marketing a new product.…”

Section: Discussionmentioning

confidence: 91%

Testing Cyclic Fatigue Resistance of Nickel Titanium Rotary Endodontic Instruments: A Validation Study for a Minimum Quality Criterion in a Standardized Environment

et al. 2021

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Introduction: Cyclic fatigue resistance of rotary endodontic instruments has been extensively studied in the last two decades, yet with no standardization. While new low-cost instruments are now manufactured, a standard is lacking to guarantee a minimum quality. This study aimed to validate a new model for CF testing through a fixture proposed for ISO Specification 3630-1 and to establish a minimum quality standard based on testing conditions and material characteristics.Materials and methods: Size 25/0.06 instruments of ProFile Vortex (PF) and Vortex Blue (VB) were run until failure in curved metallic fixtures (5 or 7.5 mm radius) built according to a proposal for an additional test for the ISO 3630-1 standard. High resolution videos were recorded, number of cycles to failure (NCF) registered and apical fragments measured with a digital caliper. Surface strain was determined from test dimensions and fragment lengths. Mean life, β and η parameters were calculated with Weibull analysis. NCF data were compared using student's t-tests and referenced to a minimum required cycles at fracture (Cmin) based on austenite finish temperatures, testing temperature and deformation.Results: VB instruments were statistically more resistant than PF in both 7.5 mm radius curve (p = 0.001) and 5 mm radius curve (p = 0.002) simulated canals. Weibull probability plots showed higher mean life for VB than PV. NCF for both instruments were higher than Cmin.Conclusions: The NCF results in this study support the findings of previous studies where VB and PF were compared. The novel test design appears a suitable addition to ISO 3630-1.

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“…Using this method, it is possible to increase the internal validity and reproducibility test, allowing a better comprehension of the resistance behaviour of the instrument and minimising biases like speed and amplitude movements that, although possible to reproduce in the dynamic model, are, in clinical situations, operator‐dependent (27). Therefore, although some editorials (29,30) present conclusions that criticise such tests' performance, they are still valid and allow the verification of several factors associated with the instruments' performance, such as changes caused by temperature and factors associated with the instrument’s geometrical features.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the mechanical properties of different nickel–titanium retreatment instruments

et al. 2020

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This study investigated the cyclic fatigue, bending, torsional resistance and angular deflection of Pro‐R 25.08, Logic RT 25.08, MK Retreatment 25.08 (MK RT) and ProTaper Retreatment D2 instruments. Cyclic fatigue test was performed until fracture in a custom stainless‐steel device with water bath equipment to simulate body temperature. Fracture time was recorded. A number of cycles were calculated. Resistance to bending at 45°, torsional resistance and angular deflection were evaluated. The fracture surfaces were examined by scanning electron microscopy. Statistical analysis was performed with one‐way ANOVA and Tukey and Kruskal–Wallis and Dunn tests. Pro‐R and Logic RT presented the highest cyclic fatigue (P < 0.05). D2 had higher strength to bend than Pro‐R and Logic RT (P < 0.05). Logic RT showed the highest torque and angular deflection (P < 0.05), without differences when compared to D2 (P > 0.05). Instrument performances were dependent on their geometrical features and heat treatments.

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Research that matters: studies on fatigue of rotary and reciprocating NiTi root canal instruments

Cited by 21 publications

References 15 publications

Effect of dentine cutting efficiency on the lateral force created by torque‐controlled rotary instruments

Effect of dentine cutting efficiency on the lateral force created by torque‐controlled rotary instruments

Testing Cyclic Fatigue Resistance of Nickel Titanium Rotary Endodontic Instruments: A Validation Study for a Minimum Quality Criterion in a Standardized Environment

Evaluation of the mechanical properties of different nickel–titanium retreatment instruments

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