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Dai Q, Wang Z, Liu C, Chen X, Cao X. High performance injectable Mg doped bioactive glass bone cement for the regulation of osteogenic immune microenvironment. BIOMATERIALS ADVANCES 2024; 160:213864. [PMID: 38642519 DOI: 10.1016/j.bioadv.2024.213864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/09/2024] [Accepted: 04/17/2024] [Indexed: 04/22/2024]
Abstract
Although calcium phosphate has been extensively utilized in orthopedic applications such as spine, limbs, dentistry, and maxillofacial surgery, the lack of osteoinductive properties often hinders its effectiveness in treating bone defects resulting from pathological micro-environment such as tumor surgery, osteoporosis, osteomyelitis, and diabetic. Therefore, a novel bone cement based on magnesium-doped bioactive glass was developed in this study. The moderate release of magnesium ions improved the mechanical properties by controlling the crystal size of hydroxyapatite. Through detailed discussion of element content and heat treatment temperature, it was found that 2Mg-BG-800 was suitable for the construction of bone cement. 2Mg-BG-BC exhibited favorable initial (15 min) and final (30 min) setting time, compressive strength (29.45 MPa), compressive modulus (1851.49 MPa), injectability, and shape-adaptability. Furthermore, Mg-BG-BC demonstrated the ability to enhance the osteogenic differentiation of BMSCs, and induce macrophage polarization towards the M2 phenotype, suggesting its potential for osteoporotic fracture regeneration.
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Affiliation(s)
- Qiyuan Dai
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, PR China
| | - Zetao Wang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, PR China
| | - Cong Liu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, PR China
| | - Xiaofeng Chen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, PR China; National Engineering Research Centre for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Xiaodong Cao
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, PR China; National Engineering Research Centre for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou 510006, PR China; Zhongshan Institute of Modern Industrial Technology of SCUT, Zhongshan, Guangdong 528437, PR China.
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2
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Xing Y, Zhong X, Chen S, Wu S, Chen K, Li X, Su M, Liu X, Zhong J, Chen Z, Pan H, Chen Z, Liu Q. Optimized osteogenesis of porcine bone-derived xenograft through surface coating of magnesium-doped nanohydroxyapatite. Biomed Mater 2023; 18:055025. [PMID: 37604162 DOI: 10.1088/1748-605x/acf25e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/21/2023] [Indexed: 08/23/2023]
Abstract
As one of the key factors influencing the outcome of guided bone regeneration, the currently used xenografts possess insufficient capability in osteogenesis. With the aim of improving the osteogenic performance of xenografts, porcine bone-derived hydroxyapatite (PHA) was prepared and subsequently coated by magnesium-doped nano hydroxyapatite (nMgHA, 10%, 20%, and 30% of Mg/Ca + Mg) through a straightforward and cost-efficient approach. The physiochemical and biological properties of nMgHA/PHAs were examinedin vitroandin vivo. The inherent three-dimensional (3D) porous framework with the average pore size of 300 μm was well preserved in nMgHA/PHAs. Meanwhile, excess magnesium released from the so-called 'surface pool' of PHA was verified. In contrast, slower release of magnesium at lower concentrations was detected for nMgHA/PHAs. Significantly more newly-formed bone and microvessels were observed in 20%nMgHA/PHA than the other specimens. With the limitations of the present study, it could be concluded that PHA coated by 20%nMgHA may have the optimized osteogenic performance due to the elimination of the excess magnesium from the 'surface pool', the preservation of the inherent 3D porous framework with the favorable pore size, and the release of magnesium at an appropriate concentration that possessed osteoimmunomodulatory effects on macrophages.
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Affiliation(s)
- Yihan Xing
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Xinyi Zhong
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Shoucheng Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Shiyu Wu
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Kaidi Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Xiyan Li
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Mengxi Su
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Xingchen Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Juan Zhong
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Zetao Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Haobo Pan
- Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055, People's Republic of China
| | - Zhuofan Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
| | - Quan Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, People's Republic of China
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Stulajterova R, Giretova M, Medvecky L, Sopcak T, Luptakova L, Girman V. The Influence of Nanosilica on Properties of Cement Based on Tetracalcium Phosphate/Monetite Mixture with Addition of Magnesium Pyrophoshate. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8212. [PMID: 36431697 PMCID: PMC9692293 DOI: 10.3390/ma15228212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/04/2022] [Accepted: 11/14/2022] [Indexed: 06/16/2023]
Abstract
The effect of nanosilica on the microstructure setting process of tetracalcium phosphate/nanomonetite calcium phosphate cement mixture (CPC) with the addition of 5 wt% of magnesium pyrophosphate (assigned as CT5MP) and osteogenic differentiation of mesenchymal stem cells cultured in cement extracts were studied. A more compact microstructure was observed in CT5MP cement with 0.5 wt% addition of nanosilica (CT5MP1Si) due to the synergistic effect of Mg2P2O7 particles, which strengthened the cement matrix and nanosilica, which supported gradual growth and recrystallization of HAP particles to form compact agglomerates. The addition of 0.5 wt% of nanosilica to CT5MP cement caused an increase in CS from 18 to 24 MPa while the setting time increased almost twofold. It was verified that adding nanosilica to CPC cement, even in a low amount (0.5 and 1 wt% of nanosilica), positively affected the injectability of cement pastes and differentiation of cells with upregulation of osteogenic markers in cells cultured in cement extracts. Results revealed appropriate properties of these types of cement for filling bone defects.
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Affiliation(s)
- Radoslava Stulajterova
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia
| | - Maria Giretova
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia
| | - Lubomir Medvecky
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia
| | - Tibor Sopcak
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia
| | - Lenka Luptakova
- Department of Biology and Physiology, University of Veterinary Medicine and Pharmacy in Kosice, Komenskeho 73, 041 81 Kosice, Slovakia
| | - Vladimir Girman
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia
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Stulajterova R, Medvecky L, Giretova M, Sopcak T, Luptakova L, Bures R, Szekiova E. Characterization of Tetracalcium Phosphate/Monetite Biocement Modified by Magnesium Pyrophosphate. MATERIALS 2022; 15:ma15072586. [PMID: 35407918 PMCID: PMC9000233 DOI: 10.3390/ma15072586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/23/2022] [Accepted: 03/25/2022] [Indexed: 11/24/2022]
Abstract
Magnesium pyrophosphate modified tetracalcium phosphate/monetite cement mixtures (MgTTCPM) were prepared by simple mechanical homogenization of compounds in a ball mill. The MgP2O7 was chosen due to the suitable setting properties of the final cements, in contrast to cements with the addition of amorphous (Ca, Mg) CO3 or newberite, which significantly extended the setting time even in small amounts (corresponding ~to 1 wt% of Mg in final cements). The results showed the gradual dissolution of the same amount of Mg2P2O7 phase, regardless of its content in the cement mixtures, and the refinement of formed HAP nanoparticles, which were joined into weakly and mutually bound spherical agglomerates. The compressive strength of composite cements was reduced to 14 MPa and the setting time was 5–10 min depending on the composition. Cytotoxicity of cements or their extracts was not detected and increased proliferative activity of mesenchymal stem cells with upregulation of osteopontin and osteonectin genes was verified in cells cultured for 7 and 15 days in cement extracts. The above facts, including insignificant changes in the pH of simulated body fluid solution and mechanical strength close to cancellous bone, indicate that MgTTCPM cement mixtures could be suitable biomaterials for use in the treatment of bone defects.
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Affiliation(s)
- Radoslava Stulajterova
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia; (R.S.); (M.G.); (T.S.); (R.B.)
| | - Lubomir Medvecky
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia; (R.S.); (M.G.); (T.S.); (R.B.)
- Correspondence:
| | - Maria Giretova
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia; (R.S.); (M.G.); (T.S.); (R.B.)
| | - Tibor Sopcak
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia; (R.S.); (M.G.); (T.S.); (R.B.)
| | - Lenka Luptakova
- Department of Biology and Physiology, University of Veterinary Medicine and Pharmacy in Kosice, Komenskeho 73, 041 81 Kosice, Slovakia;
| | - Radovan Bures
- Division of Functional and Hybrid Systems, Institute of Materials Research of SAS, Watsonova 47, 040 01 Kosice, Slovakia; (R.S.); (M.G.); (T.S.); (R.B.)
| | - Eva Szekiova
- Institute of Neurobiology of Biomedical Research Center of SAS, Soltesovej 4–6, 040 01 Kosice, Slovakia;
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Gelli R, Briccolani-Bandini L, Pagliai M, Cardini G, Ridi F, Baglioni P. Exploring the effect of Mg 2+ substitution on amorphous calcium phosphate nanoparticles. J Colloid Interface Sci 2022; 606:444-453. [PMID: 34399361 DOI: 10.1016/j.jcis.2021.08.033] [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: 07/15/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS The study of Amorphous Calcium Phosphate (ACP) has become a hot topic due to its relevance in living organisms and as a material for biomedical applications. The preparation and characterization of Mg-substituted ACP nanoparticles (AMCP) with tunable Ca/Mg ratio is reported in the present study to address the effect of Mg2+ on their structure and stability. EXPERIMENTS AMCPs particles were synthesized by precipitation of the precursors from aqueous solutions. The particles were analyzed in terms of morphology, crystallinity, and thermal stability, to get a complete overview of their physico-chemical characteristics. Computational methods were also employed to simulate the structure of ACP clusters at different levels of Mg2+ substitution. FINDINGS Our results demonstrate that AMCP particles with tunable composition and crystallinity can be obtained. The analysis of the heat-induced crystallization of AMCP shows that particles' stability depends on the degree of Mg2+ substitution in the cluster, as confirmed by computational analyses. The presented results shed light on the effect of Mg2+ on ACP features at different structural levels and may be useful guidelines for the preparation and design of AMCP particles with a specific Ca/Mg ratio.
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Affiliation(s)
- Rita Gelli
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy; CSGI, Center for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Lorenzo Briccolani-Bandini
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Marco Pagliai
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Gianni Cardini
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Francesca Ridi
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy; CSGI, Center for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
| | - Piero Baglioni
- Department of Chemistry "Ugo Schiff", University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy; CSGI, Center for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
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Gelli R, Tonelli M, Ridi F, Bonini M, Kwaambwa HM, Rennie AR, Baglioni P. Modifying the crystallization of amorphous magnesium-calcium phosphate nanoparticles with proteins from Moringa oleifera seeds. J Colloid Interface Sci 2021; 589:367-377. [DOI: 10.1016/j.jcis.2021.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 01/10/2023]
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Gelli R, Ridi F, Baglioni P. The importance of being amorphous: calcium and magnesium phosphates in the human body. Adv Colloid Interface Sci 2019; 269:219-235. [PMID: 31096075 DOI: 10.1016/j.cis.2019.04.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 11/25/2022]
Abstract
This article focuses on the relevance of amorphous calcium (and magnesium) phosphates in living organisms. Although crystalline calcium phosphate (CaP)-based materials are known to constitute the major inorganic constituents of human hard tissues, amorphous CaP-based structures, often in combination with magnesium, are frequently employed by Nature to build up components of our body and guarantee their proper functioning. After a brief description of amorphous calcium phosphate (ACP) formation mechanism and structure, this paper is focused on the stabilization strategies that can be used to enhance the lifetime of the poorly stable amorphous phase. The various locations of our body in which ACP (pure or in combination with Mg2+) can be found (i.e. bone, enamel, small intestine, calciprotein particles and casein micelles) are highlighted, showing how the amorphous nature of ACP is often of paramount importance for the achievement of a specific physiological function. The last section is devoted to ACP-based biomaterials, focusing on how these materials differ from their crystalline counterparts in terms of biological response.
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Liu R, Qiao W, Huang B, Chen Z, Fang J, Li Z, Chen Z. Fluorination Enhances the Osteogenic Capacity of Porcine Hydroxyapatite. Tissue Eng Part A 2018; 24:1207-1217. [PMID: 29376480 DOI: 10.1089/ten.tea.2017.0381] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In a previous study, we successfully prepared fluorinated porcine hydroxyapatite (FPHA) by immersing porcine hydroxyapatite (PHA) in an aqueous solution of 0.25 M sodium fluoride (NaF) under thermal treatment, and the resulting FPHA showed better physicochemical and biological properties than PHA. The purpose of this study was to further investigate how fluorine incorporation influenced the biocompatibility and osteogenic capacity of PHA. The concentrations of Ca, P, F, and Mg ions in PHA and FPHA extracts were detected by inductively coupled plasma optical emission spectrometry. Rat bone marrow stromal cells (rBMSCs) were treated with PHA and FPHA extracts, and the effects of these extracts on cell proliferation and osteoblastic differentiation were evaluated via Cell Counting Kit-8 assay, alkaline phosphatase assay, and real time-quantitative polymerase chain reaction. For the in vivo assessment, PHA and FPHA were implanted into subcutaneous pockets (n = 6) and rat calvarial defects (diameter = 5 mm, n = 14) for 12 weeks to determine their biocompatibility and osteogenic capacity by using micro-computed tomography (CT) and histological analysis. FPHA extracts, which release higher concentrations of F and Mg ions, better promoted the osteoblastic differentiation of rBMSCs in vitro. The result of biocompatibility evaluation confirmed that the host response and chronic inflammation cells infiltration degree around PHA and FPHA granules were similar. Micro-CT and histological analysis showed newer mineralized bone formation in rats with FPHA-treated defects than in rats with PHA-treated defects. The results of in vitro and in vivo tests consistently indicate that fluorine incorporation effectively enhanced the osteogenic capacity of PHA.
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Affiliation(s)
- Runheng Liu
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Wei Qiao
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Baoxin Huang
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Zetao Chen
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Jinghan Fang
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Zhipeng Li
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
| | - Zhuofan Chen
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology , Guangzhou, People's Republic of China
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Qiao W, Liu R, Li Z, Luo X, Huang B, Liu Q, Chen Z, Tsoi JKH, Su YX, Cheung KMC, Matinlinna JP, Yeung KWK, Chen Z. Contribution of the in situ release of endogenous cations from xenograft bone driven by fluoride incorporation toward enhanced bone regeneration. Biomater Sci 2018; 6:2951-2964. [DOI: 10.1039/c8bm00910d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fluoride incorporation in porcine bone-derived biological apatite can change the surrounding microenvironment via in situ ionic exchange, which accelerates bone formation by activating Wnt/β-catenin pathway.
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10
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Functionalized biomimetic calcium phosphates for bone tissue repair. J Appl Biomater Funct Mater 2017; 15:e313-e325. [PMID: 28574097 DOI: 10.5301/jabfm.5000367] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2017] [Indexed: 12/17/2022] Open
Abstract
The design and development of novel materials for biomineralized tissues is an extremely attractive field of research where calcium phosphates (CaPs)-based materials for biomedical applications play a leading role. The biological performance of these compounds can be enhanced through functionalization with biologically active ions and molecules. This review reports on some important recent achievements in creating functionalized biomimetic CaP materials for applications in the musculoskeletal field. Particular attention is focused on the modifications of these inorganic compounds with bioactive ions, growth factors and drugs, as well as on recent trends in some important CaP applications as biomaterials - namely, as bone cements, coatings of metallic implants and scaffolds for regenerative medicine.
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Hassanali L, Wong FS, Lynch RJM, Anderson P. A Novel Kinetic Method to Measure Apparent Solubility Product of Bulk Human Enamel. Front Physiol 2017; 8:714. [PMID: 28983253 PMCID: PMC5613155 DOI: 10.3389/fphys.2017.00714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 09/04/2017] [Indexed: 11/13/2022] Open
Abstract
Introduction: Tooth enamel mineral loss is influenced by its solubility product value, which is fundamental to the understanding of de- and remineralization resulting from a carious or erosive challenge. Published pKsp values for human enamel and hydroxyapatite range from 110 to 126 suggesting a heterogeneous nature of enamel solubility. However, this range of values may also result from the variety of methods used, e.g., some authors reporting values for suspensions of enamel powder and others for bulk enamel. The aim of this study was to develop a method to measure the solubility of bulk human enamel under controlled in vitro conditions simulating demineralization behavior of enamel within the oral environment using scanning microradiography (SMR). SMR was used to monitor real-time changes in enamel demineralization rates at increasing calcium concentrations in a caries simulating demineralization solution until the concentration at which thermodynamic equilibrium between enamel and solution was achieved. Method: 2 mm thick caries free erupted human enamel slabs with the natural buccal surfaces exposed were placed in SMR cells exposed to circulating caries-simulating 2.0 L 0.1 M pH = 4.0 acetic acid, at 25°C. SMR was used to continuously measure in real-time the decrease in mineral mass during the demineralization at 5 different points from on each slab. Demineralization rates were calculated from a linear regression curve of projected mineral mass against demineralization time. Changes in the demineralization rates were monitored following a series of successive increases in calcium (and phosphate at hydroxyapatite stoichiometric ratios of Ca:P 1.67) were added to the demineralizing solution, until demineralization ceased. The pH was maintained constant throughout. Results: Demineralization halted when the calcium concentration was ~30 mM. At higher calcium concentrations, mineral deposition (remineralization) occurred. By comparison with results from speciation software calculations for the calcium phosphate ternary system, this result suggests that the bulk solubility product of enamel (pKspBEnamel) under the conditions used is 121. Discussion: The apparent pKspBEnamel under these conditions was higher than many previous reported values, and much closer to those previously reported for HAp. However, this is a bulk value, and does not reflect that enamel is a heterogeneous material, nor the influence of ionic inclusions.
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Affiliation(s)
- Linda Hassanali
- Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of LondonLondon, United Kingdom
| | - Ferranti S Wong
- Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of LondonLondon, United Kingdom
| | - Richard J M Lynch
- Innovation Research and Development, Oral Healthcare, GlaxoSmithKlineWeybridge, United Kingdom
| | - Paul Anderson
- Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of LondonLondon, United Kingdom
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