Elastic Modulus and Mineral Density of Dentine and Enamel in Natural Caries Lesions

2005 ◽  
Vol 874 ◽  
Author(s):  
Amanpreet K. Bembey ◽  
Michelle L. Oyen ◽  
Ching-Chang Ko ◽  
Andrew J. Bushby ◽  
Alan Boyde
Keyword(s):  
Elastic Modulus ◽  
Mineral Content ◽  
Volume Fraction ◽  
Mineral Density ◽  
Mineral Phase ◽  
Two Phase ◽  
Dental Tissues ◽  
Carious Lesions ◽  
Phase Connectivity ◽  
Composite Mechanics

AbstractDental tissues have been reported to show a considerable decrease in both their mineral content and mechanical properties in carious lesions. The changed properties of dentine and enamel have been shown to be dependent on crystal size and not only mineral content [1], although the connectivity between the mineral crystals has been overlooked. Teeth with carious lesions were sectioned, embedded in polymethylmethacrylate (PMMA) and diamond polished. Nanoindentation and quantitative backscattered electron imaging were used to determine relationships between the elastic modulus and mineral density of sound and carious regions within dentine and enamel. The changes in elastic modulus with decreased mineralization for dentine and enamel could not be explained by simple composite mechanics expressions relating elastic modulus and mineral volume fraction. Finite element modeling of dentine and enamel as a two-phase composite material at the ultrastructure level were used to demonstrate how changes in the mineral phase connectivity can produce changes in the elastic modulus. Tissue models for enamel, in which the mineral phase is both the major component of the structure (∼ 85% by volume) and highly interconnected, were consistent with the modulus of sound enamel. The drastic change in enamel modulus with a relatively small change in mineral volume fraction could be modeled as a decrease in mineral phase connectivity at nearly constant volume fraction. The more gradual trend in the dentine data was also consistent with a structure that is initially highly connected in the mineral phase, consistent with the known structure of dentine, and for which the change in modulus is more directly related to changes in mineral content than mineral connectivity.

Mechanism of Large Elastic Modulus of Bone

2011 ◽  
Vol 689 ◽  
pp. 390-394 ◽  
Author(s):  
Bin Chen ◽  
Da Gang Yin ◽  
Ji Luo ◽  
Quan Yuan ◽  
Jing Hong Fan
Keyword(s):  
Electron Microscope ◽  
Elastic Modulus ◽  
Scanning Electron Microscope ◽  
Large Volume ◽  
Volume Fraction ◽  
Thin Fiber ◽  
Sem Observation ◽  
Large Volume Fraction ◽  
Composite Mechanics ◽  
Scanning Electron

Scanning electron microscope (SEM) observation shows that fibula bone is a kind of bioceramic composite consisting of hydroxyapatite layers and protein matters. The hydroxyapatite layers are further composed of hydroxyapatite sheets. The observation also shows that the hydroxyapatite sheets possess quite large volume fraction and also have very long and thin fiber shape. The mechanism of the large volume fraction of the hydroxyapatite sheets to ensure the larger elastic modulus of the bone was investigated based on the model of the bone composite and the theory of the composite mechanics. The investigated result reveals that the large volume fraction of the hydroxyapatite sheets endows the bone with large elastic modulus.

Finite Element Modeling of Bone Ultrastructure as a Two-phase Composite

2004 ◽  
Vol 844 ◽  
Author(s):  
Michelle L. Oyen ◽  
Ching-Chang Ko
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Aspect Ratio ◽  
Finite Element Modeling ◽  
Experimental Results ◽  
Mineral Phase ◽  
Two Phase ◽  
Element Modeling ◽  
Reinforcing Particles ◽  
Transverse Modulus

ABSTRACTBone is a composite material with a mineral hydroxyapatite (HA) phase and an organic collagen-based phase. Each phase represents about half the material by volume. The precise arrangement of these components at the ultrastructural level is unclear but of great interest in understanding the mechanical functionality of bone. Nanoindentation tests show that the elastic modulus of bone is primarily distributed between 10 GPa and 30 GPa. In this study we examine different ultrastructural arrangements of collagen and apatite phases, to test different proposed models for bone composite ultrastructure within the same finite element modeling framework. Different configurations of the composite are considered, including (a) a compliant phase with stiff reinforcing particles, (b) a stiff phase with compliant reinforcing particles, and (c) an interpenetrating two-phase (co-continuous) composite. An elastic modulus of 100 GPa is used for the mineral phase and 100 MPa for the organic phase, with volume fraction of each phase fixed at 0.5. Stiff phase continuity (as the only continuous phase in 2D and 3D or as one of two continuous phases in 3D) gives rise to effective composite elastic modulus values of 25–35 GPa, similar to the experimental results for bone modulus. Isotropic models with compliant phase continuity only give rise to moduli around 300 MPa, far below experimental results. Anisotropy was evaluated by calculating effective moduli in parallel and transverse directions relative to the primary axes of rectangular particles. High aspect ratio, stiff particles embedded in a compliant matrix do result in a substantially stiffened composite in the direction of the particles when compared to symmetric particles. However, this configuration results in a material with an effective elastic modulus of 2 GPa along the particle direction but a transverse modulus of only 250 MPa. Decreased interparticle spacing in the direction of loading was the mechanism for stiffening parallel to the particle long axis, demonstrating an indirect effect of particle aspect ratio. Although many bone models have considered the mineral as a particle reinforcement phase, the current results suggest this arrangement would not give rise to a material with bonelike properties, particularly when transverse modulus is considered, regardless of the particle geometry. Some degree of continuity of the mineral phase is required for bone-like elastic modulus values and thus a partially to fully co-continuous ultrastructural arrangement of phases is supported.

scholarly journals Comparative Study of the Measurement of Enamel Demineralization and Remineralization Using Transverse Microradiography and Electron Probe Microanalysis

2014 ◽  
Vol 20 (3) ◽  
pp. 937-945 ◽  
Author(s):  
Nathan J. Cochrane ◽  
Youichi Iijima ◽  
Peiyan Shen ◽  
Yi Yuan ◽  
Glenn D. Walker ◽  
...  
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mineral Content ◽  
Atomic Ratio ◽  
Variable Density ◽  
X Rays ◽  
Mineral Density ◽  
Dental Tissues ◽  
Human Enamel ◽  
Dental Hard Tissues

AbstractTransverse microradiography (TMR) and electron probe microanalysis (EPMA) are commonly used for characterizing dental tissues. TMR utilizes an approximately monochromatic X-ray beam to determine the mass attenuation of the sample, which is converted to volume percent mineral (vol%min). An EPMA stimulates the emission of characteristic X-rays from a variable volume of sample (dependent on density) to provide compositional information. The aim of this study was to compare the assessment of sound, demineralized, and remineralized enamel using both techniques. Human enamel samples were demineralized and a part of each was subsequently remineralized. The same line profile through each demineralized lesion was analyzed using TMR and EPMA to determine vol%min and wt% elemental composition and atomic concentration ratio information, respectively. The vol%min and wt% values determined by each technique were significantly correlated but the absolute values were not similar. This was attributable to the complex ultrastructural composition, the variable density of the samples analyzed, and the nonlinear interaction of the EPMA-generated X-rays. EPMA remains an important technique for obtaining atomic ratio information, but its limitations in determining absolute mineral content indicate that it should not be used in place of TMR for determining the mineral density of dental hard tissues.

Biomineralization of Dental Tissues Treated with Silver Diamine Fluoride

2021 ◽  
pp. 002203452110268
Author(s):  
R.M. Sulyanto ◽  
M. Kang ◽  
S. Srirangapatanam ◽  
M. Berger ◽  
F. Candamo ◽  
...  
Keyword(s):  
Primary Teeth ◽  
Spectroscopic Techniques ◽  
Mineral Density ◽  
Silver Diamine Fluoride ◽  
X Ray ◽  
Dental Tissues ◽  
Tertiary Dentin ◽  
Carious Lesions ◽  
Calcium Phosphate Particles

Silver diamine fluoride (SDF) is a dental biomaterial used to arrest dental caries. To better understand SDF’s mechanism of action, we examined the localization of silver within the tissues of SDF-treated teeth. Carious primary teeth fixed within 2 min of SDF application (SDF-minutes, n = 3), at 3 wk after SDF application in vivo (SDF-weeks, n = 4), and at 2 y after multiple SDF applications in vivo (SDF-multiple, n = 1) were investigated in this study. Carious primary teeth without SDF application (no-SDF, n = 3) served as controls. Mineral density and structural analyses were performed via micro–X-ray computed tomography and scanning electron microscopy. Elemental analyses were performed through X-ray fluorescence microprobe and energy-dispersive X-ray spectroscopic techniques. SDF-treated teeth revealed higher X-ray–attenuated surface and subsurface regions within carious lesions, and similar regions were not present in no-SDF teeth. Regions of higher mineral density correlated with regions of silver abundance in SDF-treated teeth. The SDF penetration depth was approximated to 0.5 ± 0.02 mm and 0.6 ± 0.05 mm (mean ± SD) for SDF-minutes and SDF-weeks specimens, respectively. A higher percentage of dentin tubular occlusion by silver or calcium phosphate particles was observed in primary teeth treated with SDF-weeks as compared with SDF-minutes. Elemental analysis also revealed zinc abundance in carious lesions and around the pulp chamber. SDF-weeks teeth had significantly increased tertiary dentin than SDF-minutes and no-SDF teeth. These results suggest that SDF treatment on primary teeth affected by caries promotes pathologic biomineralization by altering their physicochemical properties, occluding dentin tubules, and increasing tertiary dentin volume. These seemingly serendipitous effects collectively contribute to the cariostatic activity of SDF.

A Particle Size-Shape-Dependent Three-Phase Two-Step Mori-Tanaka Method for Studying the Interphase of Polymer/Clay Nanocomposites

2008 ◽  
Author(s):  
Yaning Li ◽  
Anthony M. Waas ◽  
Ellen M. Arruda
Keyword(s):  
Particle Size ◽  
Size Effects ◽  
Volume Fraction ◽  
Empirical Method ◽  
Clay Nanocomposites ◽  
Layer By Layer ◽  
Two Phase ◽  
Experimental Calibration ◽  
Particle Size Effects ◽  
Composite Mechanics

The enhancement of polymers by nano fillers can improve their mechanical properties beyond those achieved in macro, meso and micro composites with the same volume fraction, particle morphology and particle aspect ratio. The basic enhancement mechanism is analogous to traditional composite mechanics and can be partly explained by classical composite theories. However, the much higher enhancement efficiency of fillers at the nano scale, i.e. the particle size effects, can not be explained by classical composite mechanics theories alone. The interphase is a main structural feature of nano composites within which a significant surface-to-volume ratio is achieved, and it plays a crucial role in understanding the size effects and enhancement mechanisms of nanocomposites. In this investigation, a semi-empirical method of determining the interphase thickness and elastic properties is developed by a combination of finite element simulation, thermodynamic formulation and experimental calibration and applied to LBL (layer by layer) polyurethane-clay nanocomposites studied by Podsiadlo, et al. [1, 2] and Li, et al. [3]. Based on this study, the classical two-phase Mori-Tanaka model is extended into three-phases by introducing the interphase through a two-step procedure using the concept of an effective matrix. It is shown that this two-step Mori-Tanaka method can predict the brittle to ductile transition in terms of interphase overlap. Most importantly, this approach overcomes a serious drawback of the classic Mori-Tanaka model: size-independency. Particle size effects as well as shape effects and their interactions can be studied as applications of this method.

Influence of anthropometric parameters on assessment of paediatric bone mineral density and bone mineral content

2013 ◽  
Author(s):  
N Hangartner Thomas ◽  
F Short David ◽  
Gilsanz Vicente ◽  
J Kalkwarf Heidi ◽  
M Lappe Joan ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Bone Mineral Content ◽  
Bone Mineral ◽  
Mineral Content ◽  
Mineral Density ◽  
Anthropometric Parameters

scholarly journals Numerical Study on an Interface Compression Method for the Volume of Fluid Approach

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 80
Author(s):  
Yuria Okagaki ◽  
Taisuke Yonomoto ◽  
Masahiro Ishigaki ◽  
Yoshiyasu Hirose
Keyword(s):  
Linear Theory ◽  
Volume Fraction ◽  
Numerical Study ◽  
Volume Of Fluid ◽  
Interfacial Wave ◽  
Validation Process ◽  
Two Phase ◽  
Numerical Diffusion ◽  
Mesh Resolution ◽  
Water Reactors

Many thermohydraulic issues about the safety of light water reactors are related to complicated two-phase flow phenomena. In these phenomena, computational fluid dynamics (CFD) analysis using the volume of fluid (VOF) method causes numerical diffusion generated by the first-order upwind scheme used in the convection term of the volume fraction equation. Thus, in this study, we focused on an interface compression (IC) method for such a VOF approach; this technique prevents numerical diffusion issues and maintains boundedness and conservation with negative diffusion. First, on a sufficiently high mesh resolution and without the IC method, the validation process was considered by comparing the amplitude growth of the interfacial wave between a two-dimensional gas sheet and a quiescent liquid using the linear theory. The disturbance growth rates were consistent with the linear theory, and the validation process was considered appropriate. Then, this validation process confirmed the effects of the IC method on numerical diffusion, and we derived the optimum value of the IC coefficient, which is the parameter that controls the numerical diffusion.

scholarly journals Intra-Bone Marrow Administration of Mesenchymal Stem/Stromal Cells Is a Promising Approach for Treating Osteoporosis

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hideki Agata ◽  
Yoshinori Sumita ◽  
Tatsuro Hidaka ◽  
Mayumi Iwatake ◽  
Hideaki Kagami ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Mineral Content ◽  
Bone Mineral ◽  
Intravenous Administration ◽  
Stromal Cells ◽  
Mineral Content ◽  
Bone Diseases ◽  
Research Progress ◽  
Bone Thickness ◽  
Mineral Density

Mesenchymal stem/stromal cells (MSCs) are known to be useful for treating local bone diseases. However, it is not known if MSCs are effective for treating systemic bone diseases, as the risk for mortality following intravenous MSC administration has hindered research progress. In this study, we compared the safety and efficacy of intra-bone marrow and intravenous administration of MSCs for the treatment of ovariectomy- (OVX-) induced osteoporosis. Cells capable of forming bone were isolated from the murine compact bones and expanded in culture. Relatively pure MSCs possessing increased potential for cell proliferation, osteogenic differentiation, and inhibition of osteoclastogenesis were obtained by magnetic-activated cell sorting with the anti-Sca-1 antibody. Sca-1-sorted MSCs were administered to OVX mice, which were sacrificed 1 month later. We observed that 22% of the mice died after intravenous administration, whereas none of the mice died after intra-bone marrow administration. With respect to efficacy, intravenous administration improved bone mineral density (BMD) by increasing bone mineral content without affecting bone thickness, whereas intra-bone marrow administration improved BMD by increasing both bone mineral content and bone thickness. These results indicate that intra-bone marrow administration of pure MSCs is a safer and more effective approach for treating osteoporosis.

scholarly journals Effect of Age on Bone Structure Parameters in Laying Hens

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 570
Author(s):  
Masayoshi Yamada ◽  
Chongxiao Chen ◽  
Toshie Sugiyama ◽  
Woo Kyun Kim
Keyword(s):  
Cortical Bone ◽  
Bone Quality ◽  
Bone Mineral ◽  
Volume Fraction ◽  
Bone Structure ◽  
Bone Volume ◽  
Egg Laying ◽  
Medullary Bone ◽  
Mineral Density ◽  
Tibial Diaphysis

Changes in medullary and cortical bone structure with age remain unclear. Twenty Hy-Line W36 hens, 25 or 52 weeks of age, were euthanized, and both tibiae were collected when an egg was present in the magnum. Serial cross sections of the tibiae were stained with Alcian blue. The bones were scanned using micro-computed tomography. Trabecular width (Tb.Wi) was significantly higher (p < 0.05) in 25-week-old hens, whereas medullary bone tissue volume (TV) was significantly higher (p < 0.01) in 52-week-old hens. 25-week-old hens had significantly higher (p < 0.01) bone volume fraction (BVF = calcified tissue / TV). Moreover, the cortical bone parameters were significantly higher (TV and bone mineral content (BMC) at p < 0.05, and bone volume (BV) and BVF at p < 0.01) in younger hens. Open porosity and total porosity, which indicate less density, were significantly higher (p < 0.01) in older hens. Older hens showed significantly higher (p < 0.01) tibial diaphysis TV than younger hens. Younger hens had significantly higher (p < 0.01) BV, BVF and bone mineral density (BMD) of the tibial diaphysis. These findings reveal that reductions in medullary bone quality might be associated with age-related low estrogen levels and stimulation of osteoclastic bone resorption by parathyroid hormone. Cortical bone quality decreased with enlargement of the Haversian canals and loss of volume, with a longer egg-laying period leading to osteoporosis.

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