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Sheykhrezae MS, Meraji N, Ghanbari F, Nekoofar MH, Bolhari B, Dummer PMH. Effect of blood contamination on the compressive strength of three calcium silicate-based cements. AUST ENDOD J 2017; 44:255-259. [PMID: 28868797 DOI: 10.1111/aej.12227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2017] [Indexed: 11/30/2022]
Abstract
The aim of this study was to investigate the effect of human blood exposure on the compressive strength of various calcium silicate-based cements. Two hundred and eighty-eight customised cylindrical moulds were randomly divided into three groups according to material used: ProRoot MTA, Biodentine or CEM cement (n = 96). Each group was divided into two subgroups according to exposure conditions: PBS or blood. Then, the compressive strength of the specimens was measured after 6 h, 24 h, 72 h and 7 days. The compressive strength of CEM cement could not be measured after 6 and 24 h regardless of the exposure conditions nor could the compressive strength of 6 h blood-exposed ProRoot MTA. The compressive strength of blood-exposed ProRoot MTA was only significantly lower after 6 h, but no difference was seen at other time intervals. Blood exposed did adversely affected the compressive strength of Biodentine. The compressive strength of all groups significantly increased over time (P < 0.005).
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Affiliation(s)
- Mohammad S Sheykhrezae
- Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
| | - Naghmeh Meraji
- Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mohammad H Nekoofar
- Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.,School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Cardiff, UK
| | - Behnam Bolhari
- Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
| | - Paul M H Dummer
- School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Cardiff, UK
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Tanimoto Y, Kitagawa T, Aida M, Nishiyama N. Experimental and computational approach for evaluating the mechanical characteristics of dental composite resins with various filler sizes. Acta Biomater 2006; 2:633-9. [PMID: 16950668 DOI: 10.1016/j.actbio.2006.06.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 05/29/2006] [Accepted: 06/27/2006] [Indexed: 10/24/2022]
Abstract
This study aimed to investigate the influence of particle size of fillers on flexural properties of dental composite resins by laboratory testing with computational analysis validation. Four kinds of silica fillers with mean particle sizes of 3.3, 4.3, 7.9, and 15.5 microm were used. Filler content was kept constant at 70 mass% (or 53.8 vol.%). The three-point bending test was performed with a constant loading speed of 1.0mm/min, and a span length of 20mm using an Instron machine, in order to measure flexural strength and modulus of composite resins with various particle sizes. Test specimens were 2-mm wide, 2-mm thick, and 25-mm long rectangular bars. Furthermore, a numerical simulation using three-dimensional finite element (FE) analysis was performed to investigate stress distribution in composite resins under loading. As a result, flexural strength decreased with increasing particle size of the filler of the composite resins (p<0.05). On the other hand, there was no significant difference in Young's modulus among composite resins with various filler sizes (p>0.05). Moreover, FE analysis indicated that stress concentration increased with increasing particle size in agreement with experimental results of flexural strength. In conclusion, within the limitations of this investigation, we confirmed that flexural strength of composite resins decreased with increasing filler particle size. In addition, FE analysis was effective for evaluating stress distributions of dental composite resins with various filler sizes.
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Affiliation(s)
- Yasuhiro Tanimoto
- Department of Dental Biomaterials, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho Nishi, Matsudo, Chiba 271-8587, Japan.
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Tanimoto Y, Nishiwaki T, Nemoto K, Ben G. Effect of filler content on bending properties of dental composites: Numerical simulation with the use of the finite-element method. ACTA ACUST UNITED AC 2004; 71:188-95. [PMID: 15368244 DOI: 10.1002/jbm.b.30079] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The purpose of this work is to investigate the influence of filler content on the bending properties of dental composites by use of the finite-element method (FEM). The proposed numerical model was constructed from isotropic shell elements representing silica filler, and isotropic beam elements representing the remaining matrix resin. The proposed model was applied to failure analysis under three-point bending conditions. The validity of applying the numerical model to the failure progression analysis of composites was checked through comparison with experimental results. The results show that, in both the analytical and experimental results, the bending properties, such as maximum bending stress and bending modulus, increase with filler content. Also, the proposed method of failure progression analysis could better simulate the failure process of composites under three-point bending conditions. In addition, close agreement between the analytical and experimental results was confirmed. The above results indicate that the proposed numerical model is effective for evaluating the bending properties of dental filler composites of any content range.
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Affiliation(s)
- Yasuhiro Tanimoto
- Department of Dental Materials, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho Nishi, Matsudo, Chiba 271-8587, Japan.
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Tanimoto Y, Nishiwaki T, Nemoto K. Numerical failure analysis of glass-fiber-reinforced composites. ACTA ACUST UNITED AC 2003; 68:107-13. [PMID: 14661255 DOI: 10.1002/jbm.a.20062] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The purpose of this work was to propose a new numerical model for glass-fiber-reinforced composites. The proposed numerical model was constructed with orthotropic shell, isotropic shell, and beam elements representing glass fiber cloth, silica filler, and the remaining matrix resin, respectively. The proposed model was applied to failure analysis under three-point bending conditions. The validity of the numerical model was checked through comparisons with experimental results. Four types of specimens were used: composite resin, and composite resin with neutral, upper, and lower glass-fiber cloth reinforcement insertions. For all types, close agreement between the analytical and experimental results was confirmed. This indicates that the proposed numerical model is effective for evaluating the mechanical behaviors of glass-fiber-reinforced composites.
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Affiliation(s)
- Yasuhiro Tanimoto
- Department of Dental Materials, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho Nishi, Matsudo, Chiba 271-8587, Japan.
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Baran G, Boberick K, McCool J. Fatigue of restorative materials. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2002; 12:350-60. [PMID: 11603506 DOI: 10.1177/10454411010120040501] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Failure due to fatigue manifests itself in dental prostheses and restorations as wear, fractured margins, delaminated coatings, and bulk fracture. Mechanisms responsible for fatigue-induced failure depend on material ductility: Brittle materials are susceptible to catastrophic failure, while ductile materials utilize their plasticity to reduce stress concentrations at the crack tip. Because of the expense associated with the replacement of failed restorations, there is a strong desire on the part of basic scientists and clinicians to evaluate the resistance of materials to fatigue in laboratory tests. Test variables include fatigue-loading mode and test environment, such as soaking in water. The outcome variable is typically fracture strength, and these data typically fit the Weibull distribution. Analysis of fatigue data permits predictive inferences to be made concerning the survival of structures fabricated from restorative materials under specified loading conditions. Although many dental-restorative materials are routinely evaluated, only limited use has been made of fatigue data collected in vitro: Wear of materials and the survival of porcelain restorations has been modeled by both fracture mechanics and probabilistic approaches. A need still exists for a clinical failure database and for the development of valid test methods for the evaluation of composite materials.
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Affiliation(s)
- G Baran
- College of Engineering, Temple University, Philadelphia, PA 19122, USA.
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Baran GR, McCool JI, Paul D, Boberick K, Wunder S. Weibull models of fracture strengths and fatigue behavior of dental resins in flexure and shear. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2000; 43:226-33. [PMID: 9730059 DOI: 10.1002/(sici)1097-4636(199823)43:3<226::aid-jbm2>3.0.co;2-p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In estimating lifetimes of dental restorative materials, it is useful to have available data on the fatigue behavior of these materials. Current efforts at estimation include several untested assumptions related to the equivalence of flaw distributions sampled by shear, tensile, and compressive stresses. Environmental influences on material properties are not accounted for, and it is unclear if fatigue limits exist. In this study, the shear and flexural strengths of three resins used as matrices in dental restorative composite materials were characterized by Weibull parameters. It was found that shear strengths were lower than flexural strengths, liquid sorption had a profound effect on characteristic strengths, and the Weibull shape parameter obtained from shear data differed for some materials from that obtained in flexure. In shear and flexural fatigue, a power law relationship applied for up to 250,000 cycles; no fatigue limits were found, and the data thus imply only one flaw population is responsible for failure. Again, liquid sorption adversely affected strength levels in most materials (decreasing shear strengths and flexural strengths by factors of 2-3) and to a greater extent than did the degree of cure or material chemistry.
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Affiliation(s)
- G R Baran
- Temple University School of Dentistry, Philadelphia, Pennsylvania, USA.
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Baran G, Sadeghipour K, Jayaraman S, Silage D, Paul D, Boberick K. Crack propagation directions in unfilled resins. J Dent Res 1998; 77:1864-73. [PMID: 9823724 DOI: 10.1177/00220345980770110201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Posterior composite restorative materials undergo accelerated wear in the occlusal contact area, primarily through a fatigue mechanism. To facilitate the timely development of new and improved materials, a predictive wear model is desirable. The objective of this study was to develop a finite element model enabling investigators to predict crack propagation directions in resins used as the matrix material in composites, and to verify these predictions by observing cracks formed during the pin-on-disc wear of a 60:40 BISGMA:TEGDMA resin and an EBPADMA resin. Laser confocal scanning microscopy was used to measure crack locations. Finite element studies were done by means of ABAQUS software, modeling a cylinder sliding on a material with pre-existing surface-breaking cracks. Variables included modulus, cylinder/material friction coefficient, crack face friction, and yield behavior. Experimental results were surprising, since most crack directions were opposite previously published observations. The majority of surface cracks, though initially orthogonal to the surface, changed direction to run 20 to 30 degrees from the horizontal in the direction of indenter movement. Finite element modeling established the importance of subsurface shear stresses, since calculations provided evidence that cracks propagate in the direction of maximum K(II)(theta), in the same direction as the motion of the indenter, and at an angle of approximately 20 degrees. These findings provide the foundation for a predictive model of sliding wear in unfilled glassy resins.
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Affiliation(s)
- G Baran
- School of Dentistry, Temple University, Philadelphia, Pennsylvania 19140, USA
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Marker VA, Sakaguchi RL. Editors' remarks: Endings and beginnings. Dent Mater 1996. [DOI: 10.1016/s0109-5641(96)80049-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Huysmans MC, van der Varst PG, Lautenschlager EP, Monaghan P. The influence of simulated clinical handling on the flexural and compressive strength of posterior composite restorative materials. Dent Mater 1996; 12:116-20. [PMID: 9002853 DOI: 10.1016/s0109-5641(96)80078-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES The aim of this study was to investigate the influence of clinical handling on the flexural and compressive strengths of two commercially available posterior composites. METHODS Since the manufacturing of test specimens in a truly clinical situation presents many problems, an in vitro model was developed, consisting of a phantom-head set-up in a clinical operatory. Two composite materials, recommended for use in posterior teeth, were used: P50 APC (3M Dental Products) and Herculite XRV (Kerr, Dental Manufacturing). Beam specimens for 3-point bending tests of both materials and cylindrical specimens for compression test of P50 were made both under ideal laboratory circumstances and under simulated clinical circumstances. RESULTS The difference in mean flexural strength between laboratory prepared and the quasi-clinically prepared specimens was highly significant for both the specimens handled in a clinical manner was 15% of the flexural strength of the P50 specimens made under laboratory conditions, and the difference for Herculite XRV was 29%. No difference in compressive strength could be shown between the laboratory-fabricated and the quasi-clinically made specimens of P50. SIGNIFICANCE The relative flexural strength of composite materials in a clinical situation may differ significantly from that predicted from mechanical properties measured in vitro.
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Affiliation(s)
- M C Huysmans
- TRIKON: Institute for Dental Clinical Research, Department of Cariology and Endodontology, University of Nijmegen, The Netherlands
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Brown D, McCabe JF, Clarke RL, Nicholson J, Curtis R, Sherriff M, Hatton PV, Strang R, Ireland AJ, Watts DC. Dental materials: 1993 literature review. J Dent 1995; 23:67-93. [PMID: 7738270 DOI: 10.1016/0300-5712(95)98973-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- D Brown
- United Medical and Dental Schools, Guy's Hospital, London
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