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Bohner M, Luginbühl R, Reber C, Doebelin N, Baroud G, Conforto E. A physical approach to modify the hydraulic reactivity of alpha-tricalcium phosphate powder. Acta Biomater 2009; 5:3524-35. [PMID: 19470412 DOI: 10.1016/j.actbio.2009.05.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 05/18/2009] [Accepted: 05/19/2009] [Indexed: 11/28/2022]
Abstract
A microsized alpha-tricalcium phosphate (alpha-TCP) powder was calcined at various temperatures (350 degrees C<T<800 degrees C) for various durations (1-24h) and the resulting physico-chemical and reactivity changes were measured. Without calcination, the alpha-TCP powder started reacting within minutes after contacting a 0.2M Na(2)HPO(4) solution as measured by isothermal calorimetry. The overall reaction was finished within a few days. After calcination at 350 degrees C< or =T < or =550 degrees C for 24h, no significant changes in the crystalline composition, crystallite size, particle size or specific surface area were noticed. However, the powder reactivity was progressively changed. More specifically, the hydraulic reaction of the powders calcined at 500 and 550 degrees C only started after 2-3h whereas the overall hydraulic reaction was only slightly postponed, suggesting that physical or chemical changes had occurred at the particle surface. As mainly physical changes were detected at the particle surface during calcination at 500 degrees C, it was speculated that the appearance of this reaction delay (=induction time) was due to the disappearance of surface defects during the calcination step, i.e. to the need to create surface defects to induce dissolution and hence reaction.
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Affiliation(s)
- Marc Bohner
- RMS Foundation, Bischmattstrasse 12, PO Box 203, CH-2544 Bettlach, Switzerland.
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Ehrlich H, Koutsoukos PG, Demadis KD, Pokrovsky OS. Principles of demineralization: modern strategies for the isolation of organic frameworks. Part II. Decalcification. Micron 2008; 40:169-93. [PMID: 18804381 DOI: 10.1016/j.micron.2008.06.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 06/30/2008] [Indexed: 12/15/2022]
Abstract
This is the second paper on principles of demineralization. The initial paper is dedicated to the common definitions and the history of demineralization. In present work we review the principles and mechanisms of decalcification, i.e., removing the mineral Ca-containing compounds (phosphates and carbonates) from the organic matrix in its two main aspects: natural and artificial. Natural chemical erosion of biominerals (cavitation of biogenic calcareous substrata by bacteria, fungi, algae, foraminifera, sponges, polychaetes, and mollusks) is driven by production of mineral and organic acids, acidic polysaccharides, and enzymes (cabonic anhydrase, alkaline and phosphoprotein phosphataes, and H(+)-ATPase). Examples of artifical decalcification includes demineralization of bone, dentin and enamel, and skeletal formations of corals and crustacean. The mechanism and kinetics of Ca-containing biomineral dissolution is analyzed within the framework of (i) diffusion-reaction theory; (ii) surface-reaction controlled, morphology-based theories, and (iii) phenomenological surface coordination models. The application of surface complexation model for describing and predicting the effect of organic ligands on calcium and magnesium dissolution kinetics is also described. Use of the electron microscopy-based methods for observation and visualization of the decalcification phenomenon is discussed.
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Affiliation(s)
- Hermann Ehrlich
- Max Bergmann Center of Biomaterials, Institute of Materials Science, Dresden University of Technology, Budapester Str. 27, D-01069 Dresden, Germany.
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Bohner M, Brunner TJ, Doebelin N, Tang R, Stark WJ. Effect of thermal treatments on the reactivity of nanosized tricalcium phosphate powders. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b804314k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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McCue JT, Cecchini D, Hawkins K, Dolinski E. Use of an alternative scale-down approach to predict and extend hydroxyapatite column lifetimes. J Chromatogr A 2007; 1165:78-85. [PMID: 17706660 DOI: 10.1016/j.chroma.2007.07.053] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/20/2007] [Accepted: 07/23/2007] [Indexed: 11/25/2022]
Abstract
Ceramic hydroxyapatite (CHT) chromatography offers unique selectivity for protein purification. However, columns composed of CHT, a crystalline form of calcium phosphate, often suffer from short column lifetimes, particularly under acidic operating conditions. In this paper, CHT was used under slightly acidic conditions (pH 6) for the production scale purification of a recombinant protein. Under these conditions, the packing quality of production scale CHT columns (45 cm diameter) degraded after 5-10 cycles of operation. This was not reproduced using a conventional scale-down chromatography model, in which a constant column bed height was maintained across scales. Thus, an alternative scale-down model was developed to better predict the lifetime of large scale CHT columns. The alternative approach, which utilized a constant column diameter-to-height aspect ratio, was able to predict column failure that approximated that of the manufacturing scale column. The alternative scale-down approach was then used to test alternate buffer formulations that significantly improved the CHT column lifetime. Screening studies, which assessed the effects of mobile phase pH and composition on the dissolution (weight loss) of CHT, were used to identify the alternative mobile phase formulations. Results from the study showed that slight changes to the existing mobile phase compositions significantly increased the column lifetime, from approximately 10 cycles to approximately 65 cycles of use, without altering the purification of the recombinant protein. The alternative scale-down model, together with relatively rapid mobile phase screening studies, provides a practical approach for predicting and optimizing the useful lifetime of CHT columns for large scale applications.
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Affiliation(s)
- Justin T McCue
- Biogen Idec Corporation, Bioprocess Development, 14 Cambridge Center, MA 02142, USA.
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Barbour ME, Rees JS. The laboratory assessment of enamel erosion: a review. J Dent 2004; 32:591-602. [PMID: 15476953 DOI: 10.1016/j.jdent.2004.05.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2003] [Revised: 05/14/2004] [Accepted: 05/14/2004] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVES To review the various methods and techniques available to assess enamel erosion in vitro. DATA Peer reviewed scientific articles. SOURCES Medline and Web of Science searches and manual searching. STUDY SELECTION Laboratory based assessments only included. CONCLUSIONS A number of macroscopic and microscopic techniques have been used to assess enamel erosion in vitro and in situ. This review examines techniques which are either well established or comparatively novel techniques that are being explored for their potential.
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Affiliation(s)
- M E Barbour
- Division of Restorative Dentistry, Department of Oral and Dental Science, University of Bristol Dental School, Lower Maudlin St., Bristol BS1 2LY, UK
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Barbour ME, Parker DM, Jandt KD. Enamel dissolution as a function of solution degree of saturation with respect to hydroxyapatite: a nanoindentation study. J Colloid Interface Sci 2003; 265:9-14. [PMID: 12927157 DOI: 10.1016/s0021-9797(03)00087-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to investigate human enamel dissolution as a function of degree of saturation (DS) of the surrounding solution with respect to hydroxyapatite. Nanoindentation was used to compare changes in enamel nanomechanical properties due to dissolution by two solutions. Citric acid solution (DS=0.000, pH 3.30) and citric acid solution containing calcium (299 mg/l) and phosphate (54.0 mg/l) (DS=0.032, pH 3.30) were compared with a control mineral water (DS=0.673, pH 7.48). Exposure times were 0, 120, 300, 600, 900, and 1200 s. Compared to untreated enamel, there was a statistically significant change in enamel hardness after 120 s exposure to both citric acid solutions, and in elastic modulus after 300 s exposure. The rate of change of both variables decreased with exposure time. This suggests that dissolution rate is diffusion-limited under these conditions, in agreement with previous studies. There was no statistically significant difference between the hardness or elastic modulus of enamel exposed to the two citric acid solutions at any time. This may be due to a change in solution composition during contact with the enamel.
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Affiliation(s)
- Michele E Barbour
- Department of Oral and Dental Science, Biomedical Engineering and Biomaterials Science Section, University of Bristol, Lower Maudlin Street, Bristol, BS1 2LY, UK.
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Ji X, Chen D, Wei T, Lu X, Wang Y, Shi J. Determination of dissolution kinetics of K2SO4 crystal with ion selective electrode. Chem Eng Sci 2001. [DOI: 10.1016/s0009-2509(01)00333-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Finke M, Jandt KD, Parker DM. The Early Stages of Native Enamel Dissolution Studied with Atomic Force Microscopy. J Colloid Interface Sci 2000; 232:156-164. [PMID: 11071745 DOI: 10.1006/jcis.2000.7200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Food-induced demineralization (erosion) is one of the key factors in surface structural changes of tooth enamel, with soft drinks being a significant etiological agent. The objective of this study was to measure early stages of enamel loss with high accuracy on native enamel surfaces combined with qualitative observations of changes in the surface morphology using the atomic force microscope (AFM). Native unerupted third molar surfaces were partly covered with a gold reference layer. Samples were imaged with the AFM before dissolution (at baseline) and after exposure to three different drinks (mineral water, a "toothkind" blackcurrant drink, and a lemon and lime juice drink) at five different exposure times (15 min, 30 min, 1 h, 2 h, and 3 h). The changes in the surface morphology were investigated qualitatively as well as quantitatively. This study showed that the maximum material loss occurred at the aprismatic parts of the enamel close to the perikymata. The maximum enamel loss was greatest for the lemon and lime juice drink and lowest for water. A two-way ANOVA of the transformed data, employing the natural logarithm, showed a statistically significant difference between both the drinks and the exposure time at a 95% confidence level (P=0.000). This demonstrates that the AFM is a suitable tool for measuring early stages of enamel demineralization. Copyright 2000 Academic Press.
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Affiliation(s)
- M Finke
- Department of Oral and Dental Science, Dental Materials Science and Biomaterials Section, University of Bristol, Lower Maudlin Street, Bristol, BS1 2LY, UK
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Use of Sodium Polyaspartate for the Removal of Hydroxyapatite/Brushite Deposits from Stainless Steel Tubing. Ind Eng Chem Res 1998. [DOI: 10.1021/ie980006l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dorozhkin SV. Acidic dissolution mechanism of natural fluorapatite. I. Milli- and microlevels of investigations. JOURNAL OF CRYSTAL GROWTH 1997; 182:125-132. [DOI: 10.1016/s0022-0248(97)00330-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
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Dorozhkin SV. Acidic dissolution mechanism of natural fluorapatite. II. Nanolevel of investigations. JOURNAL OF CRYSTAL GROWTH 1997; 182:133-140. [DOI: 10.1016/s0022-0248(97)00331-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
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12
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Abstract
New experimental data about surface processes of interaction between natural apatite and phosphoric acid solutions were obtained by scanning electron microscopy, Auger electron spectroscopy, and IR reflection spectroscopy. The interaction was found to occur nonstoichiometrically (incongruently) on the very thin surface layer of apatite. The experimental data obtained were compared and extended with results taken from literature. The following sequence of ionic detachment from the surface of apatite to a solution was suggested: first fluorine for fluorapatite or hydroxyl for hydroxyapatite, next calcium, and afterward phosphate. A new chemical mechanism of apatite dissolution was proposed as a result. The mechanism for the first time described the surface irregularity of the dissolution process at the nanolevel. A comparison between this new dissolution mechanism and earlier mechanisms described in the literature was made.
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Affiliation(s)
- SV Dorozhkin
- Research Institute of Fertilizers and Insectofungicides, Kudrinskaja sq. 1-155, Moscow D-242, 123242, Russia
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Analysis of calcium hydroxyapatite dissolution in non-stoichiometric solutions. Colloids Surf A Physicochem Eng Asp 1997. [DOI: 10.1016/s0927-7757(96)03977-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Poumier F, Schaad P, Haïkel Y, Voegel J, Gramain P. Dissolution of lysozyme-coated hydroxyapatite. Colloids Surf B Biointerfaces 1996. [DOI: 10.1016/0927-7765(96)01277-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Hsu JP, Liu BT. Dissolution of solid particles in liquids: A reaction—diffusion model. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0166-6622(93)80004-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kinetics of dissolution of calcium hydroxyapatite powder IV. Interfacial calcium diffusion controlled process. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0166-6622(91)80057-u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Thomann JM, Voegel JC, Gramain P. Kinetics of dissolution of calcium hydroxyapatite powder. III: pH and sample conditioning effects. Calcif Tissue Int 1990; 46:121-9. [PMID: 2153427 DOI: 10.1007/bf02556096] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The kinetics of dissolution of synthetic hydroxyapatite powder (HAP) were studied at 37 degrees C and constant pH in the pH range 3.7-6.9 by continuously recording proton uptake and calcium release. The effect of sample conditioning was carefully investigated. The powder previously equilibrated in saturated solutions shows an initial dissolution rate higher than the one obtained when dry powder directly added to the dissolution solution is used. This effect is interpreted by considering surface state differences. As previously shown, dry powder contains important amounts of calcium and phosphate ions adsorbed onto apatite surface, ions which are desorbed during equilibration. It is assumed that the initial presence of these ions slows the dissolution rate during the first stage of the process by the formation of a permselective layer. Except for these adsorption phenomena which are less important for human enamel powder (HEP) having a lower specific surface area, it is shown that in spite of structural, morphological, and purity differences, the general dissolution behavior of HAP is quite similar to that of HEP, previously studied, and for which a quantitative model has been proposed. The dissolution rates are stirring dependent in a large range of stirring speeds and are proportional to [H+]0.64. Moreover, it is shown that in the whole range of studied pH, a calcium accumulation process occurs at the interface during the first minutes of the acidic attack. It is concluded that in our experimental conditions, the dissolution process is limited by the diffusion of calcium and/or phosphate ions in the interface.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J M Thomann
- C.T.R. Odontologiques, Inserm U-157, CNRS UA-105, Strasbourg, France
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Thomann J, Voegel J, Gumper M, Gramain P. Dissolution kinetics of human enamel powder. J Colloid Interface Sci 1989. [DOI: 10.1016/0021-9797(89)90255-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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