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Subramanian SK, Joshi V, Kalra S, Adhikari S. Unveiling the fatigue life of NiTi endodontic files: An integrated computational-experimental study. J Mech Behav Biomed Mater 2024; 157:106657. [PMID: 39024733 DOI: 10.1016/j.jmbbm.2024.106657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 07/03/2024] [Accepted: 07/07/2024] [Indexed: 07/20/2024]
Abstract
Nickel-titanium (NiTi) rotary files used in root canal treatments experience fatigue and shear damage due to the complex curved geometries and operating conditions encountered within the root canal. This can lead to premature file fracture, causing severe complications. A comprehensive understanding of how different factors contribute to file damage is crucial for improving their functional life. This study investigates the combined effects of root canal curvature radius, file canal curvature, and rotational speed on the fatigue life and failure modes of NiTi endodontic files through an integrated computational and experimental approach. Advanced finite element simulations precisely replicating the dynamic motion of files inside curved canal geometries were conducted. Critical stress/strain values were extracted and incorporated into empirical fatigue models to predict the functional life of endodontic files. Extensive experiments with files rotated inside artificial curved canals at various canal curvatures and speeds provided validation. Increasing the canal curvature beyond 60∘ and shorter curvature radii below 5 mm dramatically reduced the functional life of the endodontic file, especially at rotational speeds over 360 rpm. The Coffin-Manson fatigue model based on strain amplitude showed the closest agreement with experiments. Shear stresses dominated damage at low canal curvatures, while the combined shear-fatigue loading effects were prominent at higher canal curvatures. This conclusive study elucidates how operational parameters like canal curvature radii, canal curvature, and rotational speed synergistically influence the fatigue damage processes in NiTi files. The findings offer valuable guidelines to optimize these factors, significantly extending the functional life of endodontic files and reducing the risk of intra-operative failures. The validated computational approach provides a powerful tool for virtual testing and estimation of the functional life of the new file designs before manufacturing.
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Affiliation(s)
| | - Vivek Joshi
- Department of Mechanical Engineering, Indian Institute of Technology Jammu, India.
| | - Sahil Kalra
- Department of Mechanical Engineering, Indian Institute of Technology Jammu, India.
| | - Sondipon Adhikari
- James Watt School of Engineering, The University of Glasgow, Glasgow G12 8QQ, UK.
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Kyaw MS, Ebihara A, Iino Y, Thu M, Maki K, Kimura S, Htun PH, Okiji T. Effect of repetitive up-and-down movements on torque/force generation, surface defects and shaping ability of nickel-titanium rotary instruments: an ex vivo study. BMC Oral Health 2024; 24:986. [PMID: 39180005 PMCID: PMC11344434 DOI: 10.1186/s12903-024-04689-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 07/30/2024] [Indexed: 08/26/2024] Open
Abstract
BACKGROUND The screw-in effect is a tendency of a nickel-titanium (NiTi) rotary endodontic file to be pulled into the canal, which can result in a sudden increase in stress leading to instrument fracture, and over-instrumentation beyond the apex. To reduce screw-in force, repeated up-and-down movements are recommended to distribute flexural stress during instrumentation, especially in curved and constricted canals. However, there is no consensus on the optimal number of repetitions. Therefore, this study aimed to examine how repeated up-and-down movements at the working length affect torque/force generation, surface defects, and canal shaping ability of JIZAI and TruNatomy instruments. METHODS An original automated root canal instrumentation device was used to prepare canals and to record torque/force changes. The mesial roots of human mandibular molars with approximately 30˚ of canal curvature were selected through geometric matching using micro-computed tomography. The samples were divided into three groups according to the number of up-and-down movements at the working length (1, 3, and 6 times; n = 24 each) and subdivided according to the instruments: JIZAI (#13/0.04 taper, #25/0.04 taper, and #35/0.04 taper) or TruNatomy (#17/0.02 taper, #26/0.04 taper, and #36/0.03 tape) (n = 12 each). The design, surface defects, phase transformation temperatures, nickel-titanium ratios, torque, force, shaping ability, and surface deformation were evaluated. Data were analyzed with the Kruskal-Wallis and Dunn's tests (α = 0.05). RESULTS The instruments had different designs and phase transformation temperatures. The 3 and 6 up-and-down movements resulted in a smaller upward force compared to 1 movement (p < 0.05). TruNatomy generated significantly less maximum torque, force, and surface wear than JIZAI (p < 0.05). However, TruNatomy exhibited a larger canal deviation (p < 0.05). No statistical differences in shaping ability were detected between different up-and-down movements. CONCLUSIONS Under laboratory conditions with JIZAI and TruNatomy, a single up-and-down movement at the working length increased the screw-in force of subsequent instruments in severely curved canals in the single-length instrumentation technique. A single up-and-down movement generated more surface defects on the file when using JIZAI. TruNatomy resulted in less stress generation during instrumentation, while JIZAI better maintained the curvature of root canals.
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Affiliation(s)
- Moe Sandar Kyaw
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
- Division of Operative Dentistry, Department of Ecological Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Arata Ebihara
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
| | - Yoshiko Iino
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Myint Thu
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Keiichiro Maki
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Shunsuke Kimura
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Pyae Hein Htun
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Takashi Okiji
- Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
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Kökan EC, Atik Y, Özüpek Ş, Podnos E, Erişen R. Finite element study of the fatigue behaviour of nickel-titanium endodontic files utilised with pecking motion technique. AUST ENDOD J 2024; 50:97-109. [PMID: 37994546 DOI: 10.1111/aej.12813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 10/18/2023] [Accepted: 10/30/2023] [Indexed: 11/24/2023]
Abstract
The purpose of the study is to evaluate the influence of the pecking motion (reciprocal axial motion) surgical technique on the durability behaviour of the Nickel-Titanium endodontic files using Finite Element Analysis (FEA). A commonly used endodontic file, ProTaper Universal F2, is selected for the study. Root canal treatment procedure is simulated on a test-bench (simulated root canal) proposed by G. Gambarini for cyclic fatigue loading of endodontic files with and without the pecking motion via FEA. The hysteresis energy density is used as evaluation criteria for low cycle fatigue life estimation of Shape Memory Alloy files. In an additional study, the root canal treatment procedure is also simulated for an FEA model of a molar tooth with significant root canal curvature to understand the influence of the realistic curvature of a root canal on the fatigue behaviour of endodontic files. For the simulated root canal, analysis accurately predicts the endodontic file's failure location, and fatigue life estimation based on the hysteresis energy density is shown to increase significantly with the introduction of the pecking motion, an observation confirmed by reported experimental results. Molar tooth simulations reveal greater file fatigue resistance than in simulated root canals, confirming the pecking motion's efficacy in enhancing file durability, even in real root canal conditions. Simulations indicate that the pecking motion technique increases the fatigue life of endodontic files for simulated as well as real root canals and the hysteresis energy is confirmed as an acceptable parameter to quantify fatigue life of Nickel-Titanium endodontic files.
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Affiliation(s)
- Eyüp Can Kökan
- Department of Mechanical Engineering, Boğaziçi University, İstanbul, Turkey
| | - Yasin Atik
- Department of Mechanical Engineering, Boğaziçi University, İstanbul, Turkey
| | - Şebnem Özüpek
- Department of Mechanical Engineering, Boğaziçi University, İstanbul, Turkey
| | - Evgeny Podnos
- Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, Texas, USA
| | - Raif Erişen
- Department of Clinical Sciences, Nişantaşı University, İstanbul, Turkey
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Belladonna FG, Guimarães TDM, Silva EJNL, Vieira EDO, Lee JK, Rodrigues EDA, Souza EM, Versiani MA. Exploring the Efficacy of 6 Preparation Systems for Achieving Minimal Root Canal Transportation: A Micro-CT Investigation. J Endod 2023; 49:1722-1732. [PMID: 37717910 DOI: 10.1016/j.joen.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/02/2023] [Accepted: 09/07/2023] [Indexed: 09/19/2023]
Abstract
INTRODUCTION This study aimed to assess the canal transportation with 6 preparation systems. METHODS Sixty curved mesial roots of mandibular molars were scanned, and their root canals (n = 20 per group) were prepared with XP-endo Shaper, BioRace, ProTaper Next, Twisted File Adaptive, Reciproc, or Reciproc Blue systems. After preparation, a new scan was conducted, and transportation was determined by comparing the geometric center of the canal in 13,542 cross-sectional slices. The transport direction frequencies were recorded, and linear transport were compared using a Univariate GLM model and Tukey honestly significant difference tests (α = 5 %). RESULTS Transportation was affected by the preparation system and root third (P < .05), with no significant effect observed for the root canal (P > .05). The Twisted File Adaptive had the highest transport (P < .05), and the lowest transports were observed with XP-endo Shaper, ProTaper Next, and BioRace (P < .05). Reciproc Blue and Reciproc showed intermediate results (P < .05). The apical and coronal third exhibited the lowest and highest transportation, respectively (P < .05). A significant interaction was observed between the preparation system and root third (P < .05). In the coronal third, transportation was mostly toward the disto-inside direction, whereas in the middle and apical thirds, transportation was predominantly toward the mesio-outside direction. CONCLUSIONS XP-endo Shaper had the lowest mean linear transportation followed by the ProTaper Next, BioRace, Reciproc Blue, and Reciproc systems. The Twisted File Adaptive system had the worst performance. The direction of transportation was generally toward the inner aspect of the canal at the coronal third and toward the outer aspect of the curve at the middle and apical thirds.
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Affiliation(s)
| | | | - Emmanuel João Nogueira Leal Silva
- Department of Endodontics, Fluminense Federal University, Rio de Janeiro, Brazil; Department of Endodontics, Grande Rio University (UNIGRANRIO), Rio de Janeiro, Brazil
| | | | - Jong-Ki Lee
- Private Practice, Changwon, Republic of Korea
| | | | - Erick Miranda Souza
- Department of Dentistry II, Federal University of Maranhão, São Luís, Maranhão
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Usta SN, Solana C, Ruiz-Linares M, Baca P, Ferrer-Luque CM, Cabeo M, Arias-Moliz MT. Effectiveness of conservative instrumentation in root canal disinfection. Clin Oral Investig 2023; 27:3181-3188. [PMID: 36867258 PMCID: PMC10264279 DOI: 10.1007/s00784-023-04929-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/22/2023] [Indexed: 03/04/2023]
Abstract
OBJECTIVES The impact of conservative instrumentation on the disinfection of root canals with different curvatures has not yet been determined. This ex vivo study aimed to evaluate and compare the effect of conservative instrumentation with TruNatomy (TN) and Rotate and a conventional rotary system, ProTaper Gold (PTG), on root canal disinfection during chemomechanical preparation of straight and curved canals. MATERIALS AND METHODS Ninety mandibular molars with straight (n = 45) and curved (n = 45) mesiobuccal root canals were contaminated with polymicrobial clinical samples. Teeth were divided into three subgroups (n = 14) according to the file systems and the curvature. Canals were instrumented with TN, Rotate, and PTG, respectively. Sodium hypochlorite and EDTA were used as irrigants. Intracanal samples were taken before (S1) and after (S2) instrumentation. Six uninfected teeth were used as negative controls. The bacterial reduction between S1 and S2 was measured by ATP assay, flow cytometry, and culture methods. Kruskal-Wallis and ANOVA tests were followed by the Duncan post hoc test (p < 0.05). RESULTS Bacterial reduction percentages were similar for the three file systems in straight canals (p > 0.05). However, PTG showed a lower reduction percentage of intact membrane cells in flow cytometry than TN and Rotate (p = 0.036). For the curved canals, no significant differences were obtained (p > 0.05). CONCLUSION Conservative instrumentation of straight and curved canals using TN and Rotate files resulted in similar bacterial reduction compared to PTG. CLINICAL RELEVANCE The disinfection efficacy of conservative instrumentation is similar to conventional instrumentation in straight and curved root canals.
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Affiliation(s)
- Sıla Nur Usta
- Department of Endodontics, Gulhane Faculty of Dentistry, University of Health Sciences, Etlik, Keçiören, 06018 Ankara Turkey
| | - Carmen Solana
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Matilde Ruiz-Linares
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Pilar Baca
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Carmen María Ferrer-Luque
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Monica Cabeo
- Department of Microbiology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
| | - Maria Teresa Arias-Moliz
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
- Department of Microbiology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
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Aminoshariae A, Azarpazhooh A, Diogenes AR, Fouad AF, Glickman GN, He J, Kishen A, Letra AM, Levin L, Setzer FC, Tay FR, Hargreaves KM. Insights into the April 2022 Issue of the Journal of Endodontics. J Endod 2022; 48:427-429. [PMID: 35339235 DOI: 10.1016/j.joen.2022.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | - Amir Azarpazhooh
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Anibal R Diogenes
- University of Texas Health San Antonio School of Dentistry, San Antonio, Texas
| | - Ashraf F Fouad
- University of Alabama at Birmingham, Birmingham, Alabama
| | | | - Jianing He
- Texas A&M College of Dentistry, Dallas, Texas
| | - Anil Kishen
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Ariadne M Letra
- University of Texas Health Science Center at Houston School of Dentistry, Houston, Texas
| | | | - Frank C Setzer
- University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania
| | - Franklin R Tay
- The Dental College of Georgia, Augusta University, Augusta, Georgia
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