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Özyürek T, Uslu G, Arıcan B, Gündoğar M, Nekoofar MH, Dummer PMH. Influence of endodontic access cavity design on mechanical properties of a first mandibular premolar tooth: a finite element analysis study. Clin Oral Investig 2024; 28:433. [PMID: 39026036 PMCID: PMC11258061 DOI: 10.1007/s00784-024-05808-x] [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: 03/12/2024] [Accepted: 06/27/2024] [Indexed: 07/20/2024]
Abstract
OBJECTIVES This study aimed to investigate the influence of access cavity designs on the mechanical properties of a single-rooted mandibular first premolar tooth under various static loads using a finite element analysis. MATERIALS AND METHODS 3-dimensional FEA designs were modeled according to the access cavity designs: an intact tooth (control), traditional access cavity (TEC-I), traditional access cavity with Class-II mesio-occlusal cavity design (TEC-II), conservative access cavity (CEC), ninja access cavity (NEC), caries-driven access cavity (Cd-EC), buccal access cavity (BEC) and bucco-occlusal access cavity (BOEC). After the simulated access cavity preparations, root canal treatment was simulated and three different static loads which mimicked oblique and vertical mastication forces were applied to the models. The stress distribution and maximum Von Misses stress values were recorded. The maximum stress values were obtained on both enamel and dentin under multi-point vertical loads. RESULTS The maximum stress values were obtained on both enamel and dentin under multi-point vertical loads. Under all load types, the minimum stress distribution was observed in the control group, followed by CEC, NEC and BEC designs. The highest stress concentration was detected in Cd-EC and TEC-II designs. Under single-point vertical loading, the stress was mostly concentrated in the lingual PCD area, while under multi-point vertical loading, the entire root surface was stress-loaded except for the lingual apical third of the root. CONCLUSION Preserving tooth tissue by simulating CEC, NEC and BEC access cavities increased the load capacity of a single-rooted mandibular first premolar following simulated endodontic treatment.
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Affiliation(s)
- Taha Özyürek
- Department of Endodontics, School of Dental Medicine, Bahçeşehir University, Istanbul, Turkey
| | - Gülşah Uslu
- Department of Endodontics, Faculty of Dentistry, Çanakkale Onsekiz Mart University, Istanbul, Turkey
| | - Burçin Arıcan
- Department of Endodontics, School of Dental Medicine, Bahçeşehir University, Istanbul, Turkey.
| | - Mustafa Gündoğar
- Department of Endodontics, Faculty of Dentistry, Medipol University, Istanbul, Turkey
| | - Mohammad Hossein Nekoofar
- Department of Endodontics, School of Dental Medicine, Bahçeşehir University, Istanbul, Turkey
- Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
- Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Chien PY, Walsh LJ, Peters OA. The extended finite element method in endodontics: A scoping review and future directions for cyclic fatigue testing of nickel-titanium instruments. Clin Exp Dent Res 2024; 10:e893. [PMID: 38770579 PMCID: PMC11106644 DOI: 10.1002/cre2.893] [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: 12/12/2023] [Revised: 04/02/2024] [Accepted: 04/24/2024] [Indexed: 05/22/2024] Open
Abstract
OBJECTIVES The present study reviews the current literature regarding the utilization of the extended finite element method (XFEM) in clinical and experimental endodontic studies and the suitability of XFEM in the assessment of cyclic fatigue in rotary endodontic nickel-titanium (NiTi) instruments. MATERIAL AND METHODS An electronic literature search was conducted using the appropriate search terms, and the titles and abstracts were screened for relevance. The search yielded 13 hits after duplicates were removed, and four studies met the inclusion criteria for review. RESULTS No studies to date have utilized XFEM to study cyclic fatigue or crack propagation in rotary endodontic NiTi instruments. Challenges such as modelling material inputs and fatigue criteria could explain the lack of utilization of XFEM in the analysis of mechanical behavior in NiTi instruments. CONCLUSIONS The review showed that XFEM was seldom employed in endodontic literature. Recent work suggests potential promise in using XFEM for modelling NiTi structures.
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Affiliation(s)
- Philip Yuan‐Ho Chien
- The University of Queensland, School of Dentistry, UQ Oral Health CentreHerstonQLDAustralia
| | - Laurence James Walsh
- The University of Queensland, School of Dentistry, UQ Oral Health CentreHerstonQLDAustralia
| | - Ove Andreas Peters
- The University of Queensland, School of Dentistry, UQ Oral Health CentreHerstonQLDAustralia
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Guler MS, Guler C, Belduz Kara N, Odabasi D, Bekci ML. The stress distribution of a primary molar tooth restored with stainless steel crown using different luting cements. BMC Oral Health 2024; 24:269. [PMID: 38395853 PMCID: PMC10893635 DOI: 10.1186/s12903-024-04038-7] [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: 10/17/2023] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND The aim of this study is to evaluate the stress distributions of a primary molar tooth restored with a stainless steel crown (SSC) using resin and glass ionomer luting cements by Finite Element Analysis (FEA). METHODS Original DICOM data of a primary molar was used to create a 3D model. One model was prepared as a tooth model with SSC. A 30 μm cement layer was used in model. Two different luting cements were tested in the study: self-cure adhesive resin cement, and glass ionomer cement. Vertical and oblique loads of 330 N were applied to simulate maximum bite force and lateral forces in the occlusal contact areas of the models. Maximum von Mises stress values in the models were evaluated as MPa. RESULTS The maximum von Mises stress value was observed in the force application and general occlusal contact areas for all models. The maximum von Mises stress values were higher in the tooth model with SSC using self-cure adhesive resin cement (478.09 MPa and 214.62 MPa) than in the tooth model with SSC using glass ionomer cement (220.06 MPa and 198.72 MPa) in both vertical and oblique loading, respectively. CONCLUSIONS Depending on the magnitude of the bite force on the SSC, fracture of the luting cement materials could occur if the stress exceeds the endurance limit of the luting cement. Cementation with glass ionomer cement may help to reduce stress levels in SSC restorations of primary molars in children.
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Affiliation(s)
- Mehmet Sami Guler
- Department of Machinery and Metal Technologies, Vocational School of Technical Sciences, Ordu University, Ordu, Turkey
| | - Cigdem Guler
- Department of Pediatric Dentistry, Faculty of Dentistry, Ordu University, Ordu, Turkey
| | - Nihal Belduz Kara
- Department of Pediatric Dentistry, Faculty of Dentistry, Ordu University, Ordu, Turkey
| | - Didem Odabasi
- Department of Pediatric Dentistry, Faculty of Dentistry, Ordu University, Ordu, Turkey.
| | - Muhammed Latif Bekci
- Department of Machinery and Metal Technologies, Vocational School of Technical Sciences, Ordu University, Ordu, Turkey
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Iosif L, Dimitriu B, Niţoi DF, Amza O. Endodontic Dentistry: Analysis of Dentinal Stress and Strain Development during Shaping of Curved Root Canals. Healthcare (Basel) 2023; 11:2918. [PMID: 37998410 PMCID: PMC10671542 DOI: 10.3390/healthcare11222918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 10/25/2023] [Accepted: 10/29/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND Endodontic shaping causes stress and strain in the root canal dentin. Dentin microcracks have the potential to be later followed by root fractures occurring under the occlusal load. The aim of our research was to theoretically determine the values of such dentinal states of stress and strain during the endodontic shaping of curved root canals using finite element analysis (FEA). METHODS To highlight the stress concentrations in dentin, two geometric models were created considering the volume of the curved dental root and the contact between the endodontic file and the root canal walls. The application of forces with different values was simulated both on a uniform curved root canal and on a root canal with an apical third curvature of 25° as they would be applied during the preparation of a root canal. RESULTS In the case of the first model, which was acted upon with a force of 5 N, the deformations of the root canal appeared along the entire working length, reaching the highest values in the apical third of the root, although there were no geometric changes in the shape of the root canal. Regarding the second root model, with an apical third curvature of 25°, although the applied force was 2 N, the deformations were accompanied by geometric changes in the shape of the root, especially in the upper part of the apical third. At a higher force of 7 N exerted on the endodontic file, the geometric shape changed, and the deformation reached extreme critical values. The resulting tensile stresses appearing in the experimental structure varied similarly to the deformations. CONCLUSIONS Significant stress and strain can develop, especially in the apical third of curved root canals during their shaping, and the risk of cracks is higher for endodontically treated teeth presenting severe curvatures in the apical third of the root.
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Affiliation(s)
- Laura Iosif
- Faculty of Dentistry, University of Medicine and Pharmacy “Carol Davila” Bucharest, 17–21 Calea Plevnei Street, Sector 1, 010221 Bucharest, Romania; (L.I.); (O.A.)
| | - Bogdan Dimitriu
- Faculty of Dentistry, University of Medicine and Pharmacy “Carol Davila” Bucharest, 17–21 Calea Plevnei Street, Sector 1, 010221 Bucharest, Romania; (L.I.); (O.A.)
| | - Dan Florin Niţoi
- Faculty of Industrial Engineering and Robotics, University POLITEHNICA of Bucharest, 313 Splaiul Independenței Street, 060042 Bucharest, Romania
| | - Oana Amza
- Faculty of Dentistry, University of Medicine and Pharmacy “Carol Davila” Bucharest, 17–21 Calea Plevnei Street, Sector 1, 010221 Bucharest, Romania; (L.I.); (O.A.)
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Ince Yusufoglu S, Saricam E, Ozdogan MS. Finite Element Analysis of Stress Distribution in Root Canals When Using a Variety of Post Systems Instrumented with Different Rotary Systems. Ann Biomed Eng 2023:10.1007/s10439-023-03145-w. [PMID: 36705864 DOI: 10.1007/s10439-023-03145-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 01/11/2023] [Indexed: 01/28/2023]
Abstract
It is very important for clinicians to provide restorative treatments that provide durability for endodontically treated teeth. Trauma, occlusal premature contact, and features of teeth are some of the issues that can cause vertical root fractures (VRFs) in root canal-treated teeth. The aim of this 3-D study was to compare stress distribution on mandibular premolar teeth when using a variety of post designs instrumented with different rotary systems. Six mandibular premolar teeth were instrumented with the following tools: ProTaper Next, WaveOne (WO), Reciproc (R), ReciprocBlue (RB), F6-Skytaper, and TF-Adaptive. Teeth were scanned using cone beam computed tomography (CBCT) and the images were transferred to the Catia V5R25 software. Data were recorded in a stereolithography (STL) format. Four different post systems were used, fabricated from metal, fiber, zirconia, and titanium, respectively. Dentin, gutta, post, core, and crown models were added to the solid model. ANSYS V17.2 finite element analysis (FEA) software was used to determine stress distribution on each assembly. Finite analysis models were created that allowed for the calculation of stress distribution of 250-N loading at a 45° angle and vertical in relation to the roots. The maximum principal stress and von Mises values were higher under oblique loading on the roots. The F6-Skytaper and WO systems showed lower stress than other systems. The TF-Adaptive instrument showed higher stress distribution than the other models. Fiber and titanium posts showed lower stress than others. The F6-Skytaper, R, and RB instruments were found to be most effective in terms of displacement of the crown, resulting in the lowest stress values. Fiber and titanium posts showed better results than other post systems, while root canals instrumented with the F6-Skytaper and WO instruments were less likely to result in root fractures.
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Affiliation(s)
- Selen Ince Yusufoglu
- Department of Endodontics, Faculty of Dentistry, Ankara Yıldırım Beyazit University, Ankara, Turkey.
| | - Esma Saricam
- Department of Endodontics, Faculty of Dentistry, Ankara Yıldırım Beyazit University, Ankara, Turkey
| | - Mahmut Sertac Ozdogan
- Department of Prosthodontics, Faculty of Dentistry, Ankara Yıldırım Beyazit University, Ankara, Turkey
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Xu Z, Chen N, Wang B, Yang J, Liu H, Zhang X, Li Y, Liu L, Wu Y. Creation of the biomechanical finite element model of female pelvic floor supporting structure based on thin-sectional high-resolution anatomical images. J Biomech 2023; 146:111399. [PMID: 36509024 DOI: 10.1016/j.jbiomech.2022.111399] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 10/28/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE The main purpose of this study is to obtain a finite element biomechanical model that accurately mimics pelvic organ prolapse in women, to study pelvic floor supporting structures' biomechanical properties and function. We used thin-sectional high-resolution anatomical images (Chinese Visible Human, CVH) to reconstruct a detailed three-dimensional (3D) biomechanical finite element model of the female pelvic floor supporting structure including cardinal ligament, uterosacral ligament, levator ani muscle (LAM) and perianal body. The Valsalva maneuver was simulated by loading the uterus and bladder with a pressure increasing from 0 to 10 kPa. The stress, strain and displacement of supporting structures were calculated. The cardinal ligament, the uterosacral ligament and the LAM were stressed greatly when the uterus moved downward, and the maximum stress could reach 0.267 MPa, 1.51 MPa and 0.065 MPa respectively, and the maximum strain could reach 0.154, 0.16, 0.265, and the maximum displacement could reach 1.786 cm, 1.946 cm and 0.567 cm. Displacement of the perineal body also occurred, and its stress, strain and displacement were 0.092 MPa, 0.381, 0.73 cm. The stress, strain and displacement of the supporting structure around the urethra were 0.339 MPa, 0.169, 1.491 cm. Our model based on CVH has more detailed anatomical structures, which is superior to that based on MRI. Our simulation results were consistent with previous findings, which verified the unbalance of abdominal pressure and pelvic floor supporting structures will lead to POP, which provide a theoretical basis for pelvic floor anatomy and function as well as obstetrical surgery.
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Affiliation(s)
- Zhou Xu
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Na Chen
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Bingyu Wang
- School of Mechanical and Automotive Engineering, Xiamen University of Technology, Xiamen 36204, China
| | - Jingyi Yang
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Hongjun Liu
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Xiaoqin Zhang
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Ying Li
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Li Liu
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Yi Wu
- Department of Digital Medicine, College of Biomedical Engineering and Medical Imaging, Army Medical University (Third Military Medical University), Chongqing 400038, China.
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What meaningful information are the instruments mechanical testing giving us? A comprehensive review. J Endod 2022; 48:985-1004. [PMID: 35667567 DOI: 10.1016/j.joen.2022.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/21/2022] [Accepted: 05/26/2022] [Indexed: 11/22/2022]
Abstract
Instruments mechanical strength and flexibility are traditionally tested by running cyclic fatigue, torsional, bending, buckling and microhardness tests. Several cyclic fatigue test models have been used in endodontics, all capable of providing a curved trajectory for the instrument to rotate. The cyclic fatigue testing allowed to identify conditions that may affect the fatigue strength outcomes, such as canal radius and degree of curvature, handpiece static vs dynamic motions, test temperature, kinematics, instrument previously wear and sterilization cycles, or instrument's size and metal alloy features. Due to the international test specifications for both torsional and bending tests, the variations of their models are not as many as for cyclic fatigue. These tests have also identified conditions capable of affecting the outcomes, such as kinematics, instrument's preloading, cross-sectional diameters, or alloy heat treatments. Buckling and microhardness are less common, with the metal alloy being considered to have a major influence on the results. Instruments mechanical testing, having all these individual conditions as independent variables, allowed to understand them and moulded the way the technical procedures are performed clinically. Even though the artificiality and simplicity of these tests will hardly mimic real working situations, and independently of being capable of producing cornerstone knowledge, these tests are also associated with inconsistency, lack of reproducibility and low external validity. Several attempts have been made to increase the generalizability of the outcomes by adding test settings that intend to mimic the clinical condition. Although pertinent, these settings may also add variabilities inherent to their concepts and practical applications in the laboratory environment. Although the actual studies should be seen as laboratory mechanical tests that measure very specific parameters under very particular conditions and that by far do not mimic the clinical condition, the lower validity drawback seems to be possible to be minimized when achieving a comprehensive understanding of the instrument behaviour. A Finite Elements Method and/or a multimethod research approach may lead to superior data collection, analysis, and results' interpretation, which when associated with a reliable confounding factors control and proper study designs may be helpful tools and strategies in order to increase the reliability of the outcomes.
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Roda-Casanova V, Pérez-González A, Zubizarreta-Macho A, Faus-Matoses V. Influence of Cross-Section and Pitch on the Mechanical Response of NiTi Endodontic Files under Bending and Torsional Conditions—A Finite Element Analysis. J Clin Med 2022; 11:jcm11092642. [PMID: 35566767 PMCID: PMC9101501 DOI: 10.3390/jcm11092642] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 11/16/2022] Open
Abstract
In this article, the effects of cross-section and pitch on the mechanical response of NiTi endodontic files is studied by means of finite element analyses. The study was conducted over a set of eight endodontic rotary files, whose geometry was obtained from combinations of two cross-sections(square and triangular) and four pitches. Each file was subjected to bending and torsional analyses, simulating the testing conditions indicated in the ISO 3630 Standard, in order to assess their stiffness and mechanical strength. The results indicate that endodontic files with a square cross-section have double the stiffness of those with triangular cross-sections, both in terms of bending and torsion. For both loading modes, endodontic files with a triangular cross-section can undergo larger deformations before overload failure than those with a square cross-section: up to 20% more in bending and 40% in torsion. Moreover, under equivalent boundary conditions, endodontic files with triangular cross-sections present a higher fatigue life than those with square cross-sections: up to more than 300% higher for small pitches. The effect of pitch on the stiffness and strength of the file is smaller than that of the cross-section shape, but smaller pitches could be beneficial when using a triangularcross-section, as they increase the bending flexibility, fatigue life, and torsion stiffness. These results suggest a clinical recommendation for the use of files with a triangular-shaped cross-section and a small pitch in order to minimize ledging and maximize fatigue life. Finally, in this study, we reveal the sensitivity of the orientation of files with respect to the bending direction, which must be taken into account when designing, reporting, and interpreting test results under such loading conditions.
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Affiliation(s)
- Victor Roda-Casanova
- Department of Mechanical Engineering and Construction, Universitat Jaume I, 12071 Castelló de la Plana, Spain; (V.R.-C.); (A.P.-G.)
| | - Antonio Pérez-González
- Department of Mechanical Engineering and Construction, Universitat Jaume I, 12071 Castelló de la Plana, Spain; (V.R.-C.); (A.P.-G.)
| | - Alvaro Zubizarreta-Macho
- Department of Dentistry, Alfonso X el Sabio University, 28691 Madrid, Spain
- Department of Orthodontics, University of Salamanca, 37008 Salamanca, Spain
- Correspondence:
| | - Vicente Faus-Matoses
- Department of Stomatology, Faculty of Medicine and Dentistry, University of Valencia, 46010 Valencia, Spain;
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Ordinola-Zapata R, Lin F, Nagarkar S, Perdigão J. A critical analysis of research methods and experimental models to study the load capacity and clinical behavior of the root filled teeth. Int Endod J 2022; 55 Suppl 2:471-494. [PMID: 35263455 PMCID: PMC9314814 DOI: 10.1111/iej.13722] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 03/04/2022] [Indexed: 12/04/2022]
Abstract
The prognosis of root‐filled teeth depends not only on a successful root canal treatment but also on the restorative prognosis. This critical review discusses the advantages and limitations of various methodologies used to assess the load capacity or clinical survivability of root‐filled teeth and restorations. These methods include static loading, cyclic loading, finite element analysis and randomized clinical trials. In vitro research is valuable for preclinical screening of new dental materials or restorative modalities. It also can assist investigators or industry to decide whether further clinical trials are justified. It is important that these models present high precision and accuracy, be reproducible, and present adequate outcomes. Although in vitro models can reduce confounding by controlling important variables, the lack of clinical validation (accuracy) is a downside that has not been properly addressed. Most importantly, many in vitro studies did not explore the mechanisms of failure and their results are limited to rank different materials or treatment modalities according to the maximum load capacity. An extensive number of randomized clinical trials have also been published in the last years. These trials have provided valuable insight on the survivability of the root‐filled tooth answering numerous clinical questions. However, trials can also be affected by the selected outcome and by intrinsic and extrinsic biases. For example, selection bias, loss to follow‐up and confounding. In the clinical scenario, hypothesis‐based studies are preferred over observational and retrospective studies. It is recommended that hypothesis‐based studies minimize error and bias during the design phase.
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Affiliation(s)
- Ronald Ordinola-Zapata
- Division of Endodontics, Department of Restorative Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Fei Lin
- Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, 100081, China.,Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Sanket Nagarkar
- Park Dental Group, Minneapolis, Minnesota, and Clinical Research Assistant Professor (affiliated), Department of Restorative Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Jorge Perdigão
- Division of Operative Dentistry, Department of Restorative Sciences, University of Minnesota, Minneapolis, Minnesota, USA
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Kwak SW, Shen Y, Liu H, Kim HC, Haapasalo M. Torque Generation of the Endodontic Instruments: A Narrative Review. MATERIALS 2022; 15:ma15020664. [PMID: 35057383 PMCID: PMC8778851 DOI: 10.3390/ma15020664] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 12/21/2021] [Accepted: 12/28/2021] [Indexed: 11/30/2022]
Abstract
As the use of nickel-titanium (NiTi) file systems for root canal therapy has become popular; hence, knowledge and understanding of the characteristics of NiTi files is essential for dentists. Unintended sudden fracture can occur during root canal shaping, and it is important to understand the conditions that may cause instrument fractures. Torque is defined as the force required to rotate the NiTi file and can be considered of as a parameter for the stress generated. The endodontic engine maintains a constant rotational speed by adjusting torque regardless of the root canal conditions. The process of root canal shaping by rotary instruments is a series of actions that requires torque and generates stress to both the teeth and the NiTi instruments. The generated stress may induce the strain accumulation on NiTi instrument and the canal wall and lead to the development of microcrack in the instrument and dentinal wall. Therefore, understanding of torque and stress generated is important to prevent the fractures to the instrument and the teeth. This stress has been measured using various experimental approaches, including microcrack observation by using a microscope or computed tomography, attaching strain gauges to the teeth, and finite element analysis. This review focuses on the stress generated to the teeth and the instrument during instrumentation under various experimental conditions. The factors related to torque generation are also discussed.
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Affiliation(s)
- Sang Won Kwak
- Department of Conservative Dentistry, Dental and Life Science Institute, Dental Research Institute, School of Dentistry, Pusan National University, Yangsan 50612, Korea;
- Department of Oral Biological and Medical Sciences, Division of Endodontics, Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.S.); (H.L.)
| | - Ya Shen
- Department of Oral Biological and Medical Sciences, Division of Endodontics, Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.S.); (H.L.)
| | - He Liu
- Department of Oral Biological and Medical Sciences, Division of Endodontics, Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.S.); (H.L.)
- Department of Stomatology, Affiliated Hospital of Jining Medical University, Jining 272000, China
| | - Hyeon-Cheol Kim
- Department of Conservative Dentistry, Dental and Life Science Institute, Dental Research Institute, School of Dentistry, Pusan National University, Yangsan 50612, Korea;
- Correspondence: (H.-C.K.); (M.H.)
| | - Markus Haapasalo
- Department of Oral Biological and Medical Sciences, Division of Endodontics, Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.S.); (H.L.)
- Correspondence: (H.-C.K.); (M.H.)
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11
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Roda-Casanova V, Pérez-González A, Zubizarreta-Macho Á, Faus-Matoses V. Fatigue Analysis of NiTi Rotary Endodontic Files through Finite Element Simulation: Effect of Root Canal Geometry on Fatigue Life. J Clin Med 2021; 10:jcm10235692. [PMID: 34884394 PMCID: PMC8658234 DOI: 10.3390/jcm10235692] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 10/26/2022] Open
Abstract
This article describes a numerical procedure for estimating the fatigue life of NiTi endodontic rotary files. An enhanced finite element model reproducing the interaction of the endodontic file rotating inside the root canal was developed, which includes important phenomena that allowed increasing the degree of realism of the simulation. A method based on the critical plane approach was proposed for extracting significant strain results from finite element analysis, which were used in combination with the Coffin-Manson relation to predict the fatigue life of the NiTi rotary files. The proposed procedure is illustrated with several numerical examples in which different combinations of endodontic rotary files and root canal geometries were investigated. By using these analyses, the effect of the radius of curvature and the angle of curvature of the root canal on the fatigue life of the rotary files was analysed. The results confirm the significant influence of the root canal geometry on the fatigue life of the NiTi rotary files and reveal the higher importance of the radius of curvature with respect to the angle of curvature of the root canal.
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Affiliation(s)
- Victor Roda-Casanova
- Department of Mechanical Engineering and Construction, Universitat Jaume I, 12071 Castelló de la Plana, Spain; (V.R.-C.); (A.P.-G.)
| | - Antonio Pérez-González
- Department of Mechanical Engineering and Construction, Universitat Jaume I, 12071 Castelló de la Plana, Spain; (V.R.-C.); (A.P.-G.)
| | - Álvaro Zubizarreta-Macho
- Department of Dentistry, Alfonso X el Sabio University, 28691 Madrid, Spain
- Department of Orthodontics, University of Salamanca, 37008 Salamanca, Spain
- Correspondence:
| | - Vicente Faus-Matoses
- Department of Stomatology, Faculty of Medicine and Dentistry, University of Valencia, 46010 Valencia, Spain;
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