1
|
Novel Approach to Tooth Chemistry. Quantification of the Dental-Enamel Junction. Int J Mol Sci 2021; 22:ijms22116003. [PMID: 34199407 PMCID: PMC8199634 DOI: 10.3390/ijms22116003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 01/02/2023] Open
Abstract
The dentin-enamel junction (DEJ) is known for its special role in teeth. Several techniques were applied for the investigation of the DEJ in human sound molar teeth. The electron (EPMA) and proton (PIXE) microprobes gave consistent indications about the variability of elemental concentrations on this boundary. The locally increased and oscillating concentrations of Mg and Na were observed in the junction, in the layer adhering to the enamel and covering roughly half of the DEJ width. The chemical results were compared with the optical profiles of the junction. Our chemical and optical results were next compared with the micromechanical results (hardness, elastic modulus, friction coefficient) available in the world literature. A strong correlation of both result sets was proven, which testifies to the self-affinity of the junction structures for different locations and even for different kinds of teeth and techniques applied for studies. Energetic changes in tooth strictly connected with crystallographic transformations were calculated, and the minimum energetic status was discovered for DEJ zone. Modeling of both walls of the DEJ from optical data was demonstrated. Comparing the DEJ in human teeth with the same structure found in dinosaur, shark, and alligator teeth evidences the universality of dentin enamel junction in animal world. The paper makes a contribution to better understanding the joining of the different hard tissues.
Collapse
|
2
|
Geng S, Lei Y, Snead ML. Minimal amelogenin domain for enamel formation. JOM (WARRENDALE, PA. : 1989) 2021; 73:1696-1704. [PMID: 34456537 PMCID: PMC8386916 DOI: 10.1007/s11837-021-04687-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/31/2021] [Indexed: 06/13/2023]
Abstract
Amelogenin is the most abundant matrix protein guiding hydroxyapatite formation in enamel, the durable bioceramic tissue that covers vertebrate teeth. Here, we sought to refine structure-function for an amelogenin domain based on in vitro data showing a 42 amino acid amelogenin-derived peptide (ADP7) mimicked formation of hydroxyapatite similar to that observed for the full-length mouse 180 amino acid protein. In mice, we used CRISPR-Cas9 to express only ADP7 by the native amelogenin promoter. Analysis revealed ADP7 messenger RNA expression in developing mouse teeth with the formation of a thin layer of enamel. In vivo, ADP7 peptide partially replaced the function of the full-length amelogenin protein and its several protein isoforms. Protein structure-function relationships identified through in vitro assays can be deployed in whole model animals using CRISPR-Cas9 to validate function of a minimal protein domain to be translated for clinical use as an enamel biomimetic.
Collapse
Affiliation(s)
- Shuhui Geng
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China, 201210
| | - Yaping Lei
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
- Biology and Biologic Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Malcolm L Snead
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
| |
Collapse
|
3
|
Shimizu M, Matsui N, Sayed M, Hamba H, Obayashi S, Takahashi M, Tsuda Y, Takagaki T, Nikaido T, Tagami J. Micro-CT assessment of the effect of silver diammine fluoride on inhibition of root dentin demineralization. Dent Mater J 2021; 40:1041-1048. [PMID: 33775984 DOI: 10.4012/dmj.2020-290] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated the ability of different types of silver diammine fluoride (SDF) to inhibit dentin demineralization using micro-focused X-ray computed-tomography (µCT). Dentin specimens were divided into five groups (n=10); no-treatment (control), 3.8% SDF (RC), 38% SDF, 38% SDF with potassium iodide (SDF/KI), and potassium fluoride (KF). The treated-dentin surfaces were subjected to demineralization for 7-days and assessed using µCT to determine mineral loss (ML) values. Specimens were also analyzed with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The ML values of the SDF and KF groups were significantly lower than those of the RC and SDF/KI groups. EDS detected fluoride ions in the SDF and KF groups but not in the RC and SDF/KI groups. It was concluded that 38% SDF demonstrated a high ability to inhibit dentin demineralization while additional application of KI may diminish the inhibitory effect of SDF. The amount of dentin demineralization with SDF treatments was material dependent.
Collapse
Affiliation(s)
- Miyuki Shimizu
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Naoko Matsui
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Mahmoud Sayed
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Hidenori Hamba
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University.,Department of Operative Dentistry, Cariology and Pulp Biology, Tokyo Dental College
| | - Sho Obayashi
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Motoi Takahashi
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Yuka Tsuda
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| | - Tomohiro Takagaki
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University.,Department of Operative Dentistry, Division of Oral Functional Science and Rehabilitation, School of Dentistry, Asahi University
| | - Toru Nikaido
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University.,Department of Operative Dentistry, Division of Oral Functional Science and Rehabilitation, School of Dentistry, Asahi University
| | - Junji Tagami
- Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University
| |
Collapse
|
4
|
Obayashi S, Hamba H, Nakamura K, Nikaido T, Tagami J. Preventive effect of experimental polymer-based desensitizers with NaF on demineralization of root dentin -observed using micro-CT. Dent Mater J 2020; 39:1050-1056. [PMID: 32684611 DOI: 10.4012/dmj.2019-331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study compared the effect of experimental polymer-based desensitizers with NaF and oxalic acid (OA) for preventing root demineralization via observation using micro-CT. Bovine root dentin surfaces were treated with coating materials: no treatment; MS0(+) (MS Coat One®); MS3000(+) (MS Coat®); MS0(-); MS3000(-); MS7000(+/-); fluoride gel (NaF9000). MS; MS polymer, 0-7000; NaF concentrations, (+/-); OA. The specimens were scanned using micro-CT before and after demineralization (pH4.5, 10 h). Following this, the mean mineral loss (ML) after demineralization was calculated, and the specimens were observed under a scanning electron microscope (SEM). The ML values of MS3000(+), MS7000(-), MS7000(+) and NaF9000 were significantly lower than the other groups (p<0.05). Under an SEM, a membrane structure was observed to have formed on the dentin surface in the presence of the MS, fluoride, and OA. The experimental polymer-based desensitizer with oxalic acid and a high concentration of fluoride is effective for preventing root demineralization.
Collapse
Affiliation(s)
- Sho Obayashi
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University
| | - Hidenori Hamba
- Department of Operative Dentistry, Cariology and Pulp Biology, Tokyo Dental College
| | - Keiki Nakamura
- Department of Operative Dentistry, Cariology and Pulp Biology, Tokyo Dental College
| | - Toru Nikaido
- Department of Operative Dentistry, Division of Oral Functional Science and Rehabilitation, School of Dentistry, Asahi University
| | - Junji Tagami
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University
| |
Collapse
|
5
|
López-Álvarez M, Pérez-Davila S, Rodríguez-Valencia C, González P, Serra J. The improved biological response of shark tooth bioapatites in a comparative in vitro study with synthetic and bovine bone grafts. ACTA ACUST UNITED AC 2016; 11:035011. [PMID: 27271863 DOI: 10.1088/1748-6041/11/3/035011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Autologous bone is considered to be the gold standard for bone tissue regeneration, providing more highly efficient functional responses compared to synthetic materials, and avoiding the rejection risks of allogenic grafts. However, it presents limitations for certain types of surgery due to its high resorption levels and donor site morbidity. Different biphasic synthetic composites, based onnon-apatitic calcium phosphates enriched with apatitic phases-such as hydroxyapatite, and bioderived bone grafts of bovine and porcine origin-are proposed as lower resorption materials due to their higher crystalline structure. The present work proposes two new sources of bioapatites for bone filler applications obtained from the dentine and enameloid of shark teeth, respectively. These bioapatites each present a characteristic apatite-based composition and additional enrichments of specific trace elements, such as magnesium and fluorine, with proven roles in bone metabolism. Their processing and physicochemical characterization (SEM, FT-Raman and XRD) is presented, together with an in vitro evaluation of osteogenic activity compared to a commercial bovine mineralized matrix and synthetic HA/β TCP grafts. The results proved the globular morphology (0.5-1.5 μm) and porosity (~50 μm and ~0.5-1 μm) of shark dentine bioapatites with biphasic composition: apatitic (hydroxyapatite and apatite-(CaF)), non-apatitic (whitlockite), and an apatitic phase (fluorapatite), organized in oriented crystals in enameloid bioapatites. An evaluation of the pre-osteoblast MC3T3-E1 morphology revealed the colonization of pores in dentine bioapatites and an aligned cell growth in the oriented enameloid crystals. A higher proliferation (p < 0.01) was detected at up to 21 d in both the shark bioapatites and synthetic biphasic graft with respect to the bovine mineralized matrix. Finally, the great potential of porous biphasic dentine bioapatites enriched with Mg and the aligned fluorapatite crystals of enameloid bioapatites in promoting greater osteogenic activity was confirmed with a significantly increased ALP synthesis (p < 0.01) compared to the commercial grafts.
Collapse
Affiliation(s)
- M López-Álvarez
- New Materials Group, Applied Physics Department, Institute of Biomedical Research (IBI), University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain
| | | | | | | | | |
Collapse
|
6
|
Withers PJ. Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:20130157. [PMID: 25624521 PMCID: PMC4308984 DOI: 10.1098/rsta.2013.0157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored.
Collapse
Affiliation(s)
- P J Withers
- Manchester X-ray Imaging Facility, School of Materials, Manchester University, Manchester M13 9PL, UK Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK
| |
Collapse
|
7
|
Lodha E, Hamba H, Nakashima S, Sadr A, Nikaido T, Tagami J. Effect of different desensitizers on inhibition of bovine dentin demineralization: micro-computed tomography assessment. Eur J Oral Sci 2014; 122:404-10. [PMID: 25363830 DOI: 10.1111/eos.12155] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2014] [Indexed: 11/26/2022]
Abstract
This study evaluated the effect of two desensitizers on inhibition of dentin demineralization, after immersion in artificial saliva using micro-computed tomography (μCT). Dentin blocks cut from bovine incisors were treated with deionized water (DW, a negative control) or one of three desensitizers: a fluoride varnish (Duraphat, a positive control), a calcium phosphate desensitizer (Teethmate Desensitizer), and a fluoro-alumino-calcium silicate-based desensitizer (Nanoseal). After each treatment, the specimens in Duraphat, Nanoseal, and Teethmate Desensitizer groups were pre-immersed in artificial saliva (pH 6.5) for either 1 d or 1 wk. The mineral loss of the specimens after demineralization (pH 5.0, 3 h) was evaluated by μCT. The treated surface was investigated with scanning electron microscopy. Mineral loss in all treatment groups was significantly lower than that in DW. Duraphat was the most effective treatment against demineralization, followed by Nanoseal. Nanoseal showed significantly better reduction in mineral loss following immersion for 1 wk in artificial saliva than for 1 d. However, Teethmate Desensitizer and Duraphat did not exhibit enhanced inhibition of demineralization over a longer period of immersion in artificial saliva. Scanning electron microscopy images showed deposition of particles on the dentin in both Teethmate Desensitizer. The application of Teethmate Desensitizer and Nanoseal to the exposed dentin surface resulted in inhibition of demineralization, with Nanoseal resulting in improved inhibition after prolonged immersion in artificial saliva.
Collapse
Affiliation(s)
- Ena Lodha
- Department of Cariology and Operative Dentistry, Division of Oral Health Sciences, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
8
|
Piecewise-constant-model-based interior tomography applied to dentin tubules. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:892451. [PMID: 23509603 PMCID: PMC3594914 DOI: 10.1155/2013/892451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/16/2013] [Indexed: 11/17/2022]
Abstract
Dentin is a hierarchically structured biomineralized composite material, and dentin's tubules are difficult to study in situ. Nano-CT provides the requisite resolution, but the field of view typically contains only a few tubules. Using a plate-like specimen allows reconstruction of a volume containing specific tubules from a number of truncated projections typically collected over an angular range of about 140°, which is practically accessible. Classical computed tomography (CT) theory cannot exactly reconstruct an object only from truncated projections, needless to say a limited angular range. Recently, interior tomography was developed to reconstruct a region-of-interest (ROI) from truncated data in a theoretically exact fashion via the total variation (TV) minimization under the condition that the ROI is piecewise constant. In this paper, we employ a TV minimization interior tomography algorithm to reconstruct interior microstructures in dentin from truncated projections over a limited angular range. Compared to the filtered backprojection (FBP) reconstruction, our reconstruction method reduces noise and suppresses artifacts. Volume rendering confirms the merits of our method in terms of preserving the interior microstructure of the dentin specimen.
Collapse
|
9
|
Zhi QH, Lo ECM, Kwok ACY. Anin vitrostudy of silver and fluoride ions on remineralization of demineralized enamel and dentine. Aust Dent J 2013; 58:50-6. [DOI: 10.1111/adj.12033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2012] [Indexed: 11/27/2022]
Affiliation(s)
| | - ECM Lo
- Faculty of Dentistry; University of Hong Kong; Hong Kong; China
| | - ACY Kwok
- Faculty of Dentistry; University of Hong Kong; Hong Kong; China
| |
Collapse
|
10
|
Enax J, Prymak O, Raabe D, Epple M. Structure, composition, and mechanical properties of shark teeth. J Struct Biol 2012; 178:290-9. [PMID: 22503701 DOI: 10.1016/j.jsb.2012.03.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/18/2012] [Accepted: 03/21/2012] [Indexed: 11/17/2022]
Abstract
The teeth of two different shark species (Isurus oxyrinchus and Galeocerdo cuvier) and a geological fluoroapatite single crystal were structurally and chemically characterized. In contrast to dentin, enameloid showed sharp diffraction peaks which indicated a high crystallinity of the enameloid. The lattice parameters of enameloid were close to those of the geological fluoroapatite single crystal. The inorganic part of shark teeth consisted of fluoroapatite with a fluoride content in the enameloid of 3.1 wt.%, i.e., close to the fluoride content of the geological fluoroapatite single crystal (3.64 wt.%). Scanning electron micrographs showed that the crystals in enameloid were highly ordered with a special topological orientation (perpendicular towards the outside surface and parallel towards the center). By thermogravimetry, water, organic matrix, and biomineral in dentin and enameloid of both shark species were determined. Dentin had a higher content of water, organic matrix, and carbonate than enameloid but contained less fluoride. Nanoindentation and Vicker's microhardness tests showed that the enameloid of the shark teeth was approximately six times harder than the dentin. The hardness of shark teeth and human teeth was comparable, both for dentin and enamel/enameloid. In contrast, the geological fluoroapatite single crystal was much harder than both kinds of teeth due to the absence of an organic matrix. In summary, the different biological functions of the shark teeth ("tearing" for Isurus and "cutting" for Galeocerdo) are controlled by the different geometry and not by the chemical or crystallographic composition.
Collapse
Affiliation(s)
- Joachim Enax
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstr. 5-7, 45117 Essen, Germany
| | | | | | | |
Collapse
|
11
|
Stock SR, Veis A, Telser A, Cai Z. Near tubule and intertubular bovine dentin mapped at the 250 nm level. J Struct Biol 2011; 176:203-11. [PMID: 21821132 DOI: 10.1016/j.jsb.2011.07.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/21/2011] [Accepted: 07/23/2011] [Indexed: 11/29/2022]
Abstract
In this study, simultaneous diffraction and fluorescence mapping with a (250nm)(2), 10.1keV synchrotron X-ray beam investigated the spatial distribution of carbonated apatite (cAp) mineral and elemental Ca (and other cations including Zn) around dentin tubules. In 1μm thick sections of near-pulp root dentin, where peritubular dentin (PTD) is newly forming, high concentrations of Zn, relative to those in intertubular dentin (ITD), were observed adjacent to and surrounding the tubule lumens. Some but not all tubules exhibited hypercalcified collars (high Ca signal relative to the surrounding ITD), and, when present, the zone of high Ca did not extend around the tubule. Diffraction rings from cAp 00.2 and 11.2+21.1+30.0 reflections were observed, and cAp was the only crystal phase detected. Profiles of Ca, Zn and cAp diffracted intensities showed the same transitions from solid to tubule lumen, indicating the same cAp content and organization in ITD far from the tubules and adjacent to them. Further, the matching Ca and diffraction profiles demonstrated that all of the Ca is in cAp or that any noncrystalline Ca was uniformly distributed throughout the dentin. Variation of 00.2 and 11.2+21.1+30.0 diffracted intensity was consistent with the expected biaxial crystallographic texture. Extension of X-ray mapping from near 1μm resolution to the 250nm level, performed here for dentin and its tubules, will provide new understanding of other mineralized tissues.
Collapse
Affiliation(s)
- S R Stock
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Mail Code S215, 303 E. Chicago Ave., Chicago, IL 60611-3008, USA.
| | | | | | | |
Collapse
|
12
|
Nano-scale structure and mechanical properties of the human dentine–enamel junction. J Mech Behav Biomed Mater 2011; 4:785-95. [DOI: 10.1016/j.jmbbm.2010.09.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/29/2010] [Accepted: 09/13/2010] [Indexed: 11/19/2022]
|
13
|
Hamba H, Nikaido T, Inoue G, Sadr A, Tagami J. Effects of CPP-ACP with sodium fluoride on inhibition of bovine enamel demineralization: A quantitative assessment using micro-computed tomography. J Dent 2011; 39:405-13. [DOI: 10.1016/j.jdent.2011.03.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 02/21/2011] [Accepted: 03/18/2011] [Indexed: 11/25/2022] Open
|
14
|
Märten A, Fratzl P, Paris O, Zaslansky P. On the mineral in collagen of human crown dentine. Biomaterials 2010; 31:5479-90. [DOI: 10.1016/j.biomaterials.2010.03.030] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 03/15/2010] [Indexed: 11/30/2022]
|
15
|
Almer JD, Stock SR. High energy X-ray scattering quantification of in situ-loading-related strain gradients spanning the dentinoenamel junction (DEJ) in bovine tooth specimens. J Biomech 2010; 43:2294-300. [PMID: 20541209 DOI: 10.1016/j.jbiomech.2010.04.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 04/01/2010] [Accepted: 04/28/2010] [Indexed: 10/19/2022]
Abstract
High energy X-ray scattering (80.7keV photons) at station 1-ID of the Advanced Photon Source quantified internal strains as a function of applied stress in mature bovine tooth. These strains were mapped from dentin through the dentinoenamel junction (DEJ) into enamel as a function of applied compressive stress in two small parallelepiped specimens. One specimen was loaded perpendicular to the DEJ and the second parallel to the DEJ. Internal strains in enamel and dentin increased and, as expected from the relative values of the Young's modulus, the observed strains were much higher in dentin than in enamel. Large strain gradients were observed across the DEJ, and the data suggest that the mantle dentin-DEJ-aprismatic enamel structure may shield the near-surface volume of the enamel from large strains. In the enamel, drops in internal strain for applied stresses above 40MPa also suggest that this structure had cracked.
Collapse
Affiliation(s)
- J D Almer
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | | |
Collapse
|
16
|
Deymier-Black A, Almer J, Stock S, Haeffner D, Dunand D. Synchrotron X-ray diffraction study of load partitioning during elastic deformation of bovine dentin. Acta Biomater 2010; 6:2172-80. [PMID: 19925891 DOI: 10.1016/j.actbio.2009.11.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 11/10/2009] [Accepted: 11/11/2009] [Indexed: 11/25/2022]
Abstract
The elastic properties of dentin, a biological composite consisting of stiff hydroxyapatite (HAP) nano-platelets within a compliant collagen matrix, are determined by the volume fraction of these two phases and the load transfer between them. We have measured the elastic strains in situ within the HAP phase of bovine dentine by high energy X-ray diffraction for a series of static compressive stresses at ambient temperature. The apparent HAP elastic modulus (ratio of applied stress to elastic HAP strain) was found to be 18+/-2GPa. This value is significantly lower than the value of 44GPa predicted by the lower bound load transfer Voigt model, using HAP and collagen volume fractions determined by thermo-gravimetric analysis. This discrepancy is explained by (i) a reduction in the intrinsic Young's modulus of the nano-size HAP platelets due to the high fraction of interfacial volume and (ii) an increase in local stresses due to stress concentration around the dentin tubules.
Collapse
|
17
|
Lo E, Zhi Q, Itthagarun A. Comparing two quantitative methods for studying remineralization of artificial caries. J Dent 2010; 38:352-9. [DOI: 10.1016/j.jdent.2010.01.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 01/05/2010] [Accepted: 01/07/2010] [Indexed: 10/20/2022] Open
|
18
|
Kolmas J, Kalinowski E, Wojtowicz A, Kolodziejski W. Mid-infrared reflectance microspectroscopy of human molars: Chemical comparison of the dentin–enamel junction with the adjacent tissues. J Mol Struct 2010. [DOI: 10.1016/j.molstruc.2009.12.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
19
|
Neues F, Epple M. X-ray microcomputer tomography for the study of biomineralized endo- and exoskeletons of animals. Chem Rev 2008; 108:4734-41. [PMID: 18754688 DOI: 10.1021/cr078250m] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Frank Neues
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 45117 Essen, Germany
| | | |
Collapse
|