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Mineral Bone Cements: Current Status and Future Prospects

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: closed (31 December 2019) | Viewed by 61085

Special Issue Editors


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Guest Editor
Centre for Translational Bone, Joint and Soft Tissue Research, Faculty of Medicine and University Hospital, Technische Universität Dresden, 01307 Dresden, Germany
Interests: biomaterials; calcium phosphates; biopolymers; 3D printing; tissue engineering
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Functional Materials in Medicine and Dentistry, Würzburg University, Würzburg, Germany
Interests: calcium phosphate cement chemistry; degradable magnesium phosphate cements; additive manufacturing approaches; cement-polymer composites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Self-setting mineral bone cements, mostly based on calcium and magnesium phosphates, but also silicate phases, are important bone replacement materials, successfully used in clinics for many years. In the last decade, significant progress was achieved—for example, concerning the increase in the mechanical strength by fibre reinforcement, modification with biologically-active metal ions, improved drug loading and release capabilities, the development of novel cements with higher degradation ability, and successful utilization of such cements in additive manufacturing technologies. In addition, some composite materials were presented, e.g., by combining the advantages of fast-degrading silicates with mechanically more stable calcium phosphates or the simultaneous formation of a hydrogel and cement phase (dual-setting approach) to create ductile cement–polymer composites.

The present Special Issue aims to provide an overview of the state-of-the-art in self-setting, inorganic biocements for medical applications and give insights on novel research directions in this fast-developing field of research.

We invite all colleagues to submit manuscripts (full papers, communications, and reviews) to this Special Issue. Submitted manuscripts may cover all aspects, ranging from basic investigations into cement chemistry to novel processing approaches, cement modifications to adjust material and biological properties and in vitro and in vivo testing of the materials.

Michael Gelinsky
Uwe Gbureck
Guest Editors

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Keywords

  • bone cement
  • calcium phosphate
  • silicate
  • self-setting
  • bone defect
  • composite
  • reinforcement

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Published Papers (13 papers)

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Research

9 pages, 1267 KiB  
Article
Magnesium Phosphate Cement as Mineral Bone Adhesive
by Theresa Brückner, Markus Meininger, Jürgen Groll, Alexander C. Kübler and Uwe Gbureck
Materials 2019, 12(23), 3819; https://doi.org/10.3390/ma12233819 - 21 Nov 2019
Cited by 21 | Viewed by 3979
Abstract
Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability [...] Read more.
Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability of different magnesium phosphate cements (MPC) to adhere on bovine cortical bone substrates. The cements were obtained from a mixture of farringtonite (Mg3(PO4)2) with different amounts of phytic acid (C6H18O24P6, inositol hexaphosphate, IP6), whereas cement setting occurred by a chelation reaction between Mg2+ ions and IP6. We were able to show that cements with 25% IP6 and a powder-to-liquid ratio (PLR) of 2.0 g/mL resulted in shear strengths of 0.81 ± 0.12 MPa on bone even after 7 d storage in aqueous conditions. The samples showed a mixed adhesive–cohesive failure with cement residues on the bone surface as indicated by scanning electron microscopy and energy-dispersive X-ray analysis. The presented material demonstrated appropriate bonding characteristics, which could enable a broadening of the mineral bone cements’ application field to bone adhesives. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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13 pages, 2148 KiB  
Article
Adhesive Cements That Bond Soft Tissue Ex Vivo
by Xiuwen Li, Michael Pujari-Palmer, David Wenner, Philip Procter, Gerard Insley and Håkan Engqvist
Materials 2019, 12(15), 2473; https://doi.org/10.3390/ma12152473 - 3 Aug 2019
Cited by 17 | Viewed by 6908
Abstract
The aim of the present study was to evaluate the soft tissue bond strength of a newly developed, monomeric, biomimetic, tissue adhesive called phosphoserine modified cement (PMC). Two types of PMCs were evaluated using lap shear strength (LSS) testing, on porcine skin: a [...] Read more.
The aim of the present study was to evaluate the soft tissue bond strength of a newly developed, monomeric, biomimetic, tissue adhesive called phosphoserine modified cement (PMC). Two types of PMCs were evaluated using lap shear strength (LSS) testing, on porcine skin: a calcium metasilicate (CS1), and alpha tricalcium phosphate (αTCP) PMC. CS1 PCM bonded strongly to skin, reaching a peak LSS of 84, 132, and 154 KPa after curing for 0.5, 1.5, and 4 h, respectively. Cyanoacrylate and fibrin glues reached an LSS of 207 kPa and 33 kPa, respectively. αTCP PMCs reached a final LSS of ≈110 kPa. In soft tissues, stronger bond strengths were obtained with αTCP PMCs containing large amounts of amino acid (70–90 mol%), in contrast to prior studies in calcified tissues (30–50 mol%). When αTCP particle size was reduced by wet milling, and for CS1 PMCs, the strongest bonding was obtained with mole ratios of 30–50% phosphoserine. While PM-CPCs behave like stiff ceramics after setting, they bond to soft tissues, and warrant further investigation as tissue adhesives, particularly at the interface between hard and soft tissues. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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19 pages, 4617 KiB  
Article
Adsorption of Serum Albumin onto Octacalcium Phosphate in Supersaturated Solutions Regarding Calcium Phosphate Phases
by Ryo Hamai, Kaori Tsuchiya and Osamu Suzuki
Materials 2019, 12(14), 2333; https://doi.org/10.3390/ma12142333 - 23 Jul 2019
Cited by 12 | Viewed by 7013
Abstract
Octacalcium phosphate (OCP) has been shown to enhance new bone formation, coupled with its own biodegradation, through osteoblasts and osteoclast-like cell activities concomitant with de novo hydroxyapatite (HA) formation and serum protein accumulation on its surface. However, the nature of the chemical environment [...] Read more.
Octacalcium phosphate (OCP) has been shown to enhance new bone formation, coupled with its own biodegradation, through osteoblasts and osteoclast-like cell activities concomitant with de novo hydroxyapatite (HA) formation and serum protein accumulation on its surface. However, the nature of the chemical environment surrounding OCP and how it affects its metabolism and regulates protein accumulation is unknown. The present study examined how the degree of supersaturation (DS) affects the bovine serum albumin (BSA) adsorption onto OCP in 150 mM Tris-HCl buffer at 37 °C and pH 7.4, by changing the Ca2+ ion concentration. The amount of BSA adsorbed onto OCP increased as the DS increased. In addition, the amount of newly formed calcium phosphate, which could be OCP, was increased, not only by increases in DS, but also at lower equilibrium concentrations of BSA. The increased adsorption capacity of BSA was likely related to the formation of calcium phosphate on the adsorbed OCP. Together the results suggested that the formation of new calcium phosphate crystals is dependent on both the DS value and the adsorbate protein concentration, which may control serum protein accumulation on the OCP surface in vivo. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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16 pages, 5458 KiB  
Article
Strontium-Substituted Dicalcium Silicate Bone Cements with Enhanced Osteogenesis Potential for Orthopaedic Applications
by Wenjuan Liu, Zhiguang Huan, Min Xing, Tian Tian, Wei Xia, Chengtie Wu, Zhihua Zhou and Jiang Chang
Materials 2019, 12(14), 2276; https://doi.org/10.3390/ma12142276 - 15 Jul 2019
Cited by 15 | Viewed by 4041
Abstract
Incorporating Sr element in biomaterials for bone implants is an effective way to improve their biological performance, as Sr element has been proved to enhance bone regeneration and depress bone resorption activity. In the present study, we developed a Sr-incorporated dicalcium silicate (C2S) [...] Read more.
Incorporating Sr element in biomaterials for bone implants is an effective way to improve their biological performance, as Sr element has been proved to enhance bone regeneration and depress bone resorption activity. In the present study, we developed a Sr-incorporated dicalcium silicate (C2S) bone cement as a potential candidate for bioactive self-setting bone cement in orthopaedics and stomatology. The Sr-C2S powders containing 0.3–6.8% Sr in molar ratio were prepared by means of chemical co-precipitation, and the results of XRD analysis indicated the incorporation of Sr element into the lattice of C2S. Sr-C2S bone cements, as prepared by mixing the powders with water, have a final setting time of 570 to 594 min, and compressive strength higher than that of C2S bone cement within certain incorporation range. The Sr-C2S bone cements possessed good in vitro bioactivity by inducing apatite formation in simulated body fluid (SBF) within 7 days. Moreover, the proliferation activity of human bone marrow mesenchymal stem cells (hBMSCs) with Sr-C2S bone cements was significantly higher than that with C2S bone cement, and the alkaline phosphatase (ALP) activity of hBMSCs was also enhanced with addition of Sr element in Sr-C2S groups. The Sr-C2S might therefore be a bioactive self-setting material with enhanced biological performance and holds the prospect for application in the bone regeneration area. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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13 pages, 2740 KiB  
Article
Development and Bone Regeneration Capacity of Premixed Magnesium Phosphate Cement Pastes
by Andrea Ewald, Dorothea Kreczy, Theresa Brückner, Uwe Gbureck, Melanie Bengel, Andreas Hoess, Berthold Nies, Julia Bator, Uwe Klammert and Andreas Fuchs
Materials 2019, 12(13), 2119; https://doi.org/10.3390/ma12132119 - 1 Jul 2019
Cited by 32 | Viewed by 4688
Abstract
Magnesium phosphate cements (MPC) have been demonstrated to have a superior bone regeneration capacity due to their good solubility under in vivo conditions. While in the past only aqueous MPC pastes have been applied, the current study describes the fabrication and in vitro/in [...] Read more.
Magnesium phosphate cements (MPC) have been demonstrated to have a superior bone regeneration capacity due to their good solubility under in vivo conditions. While in the past only aqueous MPC pastes have been applied, the current study describes the fabrication and in vitro/in vivo testing of an oil-based calcium doped magnesium phosphate (CaMgP) cement paste. Premixed oil-based pastes with CaMgP chemistry combine the advantages of conventional MPC such as high mechanical strength and good resorbability with a prolonged shelf-life and an easier clinical handling. The pastes set in an aqueous environment and predominantly form struvite and achieve a compressive strength of ~8–10 MPa after setting. The implantation into a drill-hole defect at the distal femoral condyle of New Zealand white rabbits over a course of 6 and 12 weeks demonstrated good biocompatibility of the materials without the formation of soft connective tissue or any signs of inflammation. In contrast to a hydroxyapatite forming reference paste, the premixed CaMgP pastes showed subsequent degradation and bony regeneration. The CaMgP cement pastes presented herein are promising bone replacement materials with excellent material properties for an improved and facilitated clinical application. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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24 pages, 6593 KiB  
Article
Setting Mechanism of a CDHA Forming α-TCP Cement Modified with Sodium Phytate for Improved Injectability
by Jan Weichhold, Uwe Gbureck, Friedlinde Goetz-Neunhoeffer and Katrin Hurle
Materials 2019, 12(13), 2098; https://doi.org/10.3390/ma12132098 - 29 Jun 2019
Cited by 13 | Viewed by 3437
Abstract
A calcium deficient hydroxyapatite (CDHA) forming cement with a bimodal grain size distribution, composed of α-TCP and fine grained CDHA at a weight ratio of 9:1, was modified by the addition of sodium phytate (IP6) in variable amounts ranging from 0.25 to 2 [...] Read more.
A calcium deficient hydroxyapatite (CDHA) forming cement with a bimodal grain size distribution, composed of α-TCP and fine grained CDHA at a weight ratio of 9:1, was modified by the addition of sodium phytate (IP6) in variable amounts ranging from 0.25 to 2 wt.%, related to the powder content. The injectability of the cement paste was drastically increased by the IP6 addition, independent of the amount of added IP6. Additionally, the cement paste viscosity during the first minutes decreased. These effects could be clearly related to a slightly more negative zeta potential. Furthermore, IP6 was shown to strongly retard the setting reaction, as can be seen both in the calorimetry and X-ray diffraction measurements. In addition, octacalcium phosphate (OCP) was identified as a further setting product. All measurements were performed at 23 °C and 37 °C to assess the effect of temperature on the setting reaction for both clinical handling by the surgeon and the final hardening in the bone defect. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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16 pages, 3644 KiB  
Article
Development and Characterization of Composites Consisting of Calcium Phosphate Cements and Mesoporous Bioactive Glass for Extrusion-Based Fabrication
by Richard Frank Richter, Tilman Ahlfeld, Michael Gelinsky and Anja Lode
Materials 2019, 12(12), 2022; https://doi.org/10.3390/ma12122022 - 24 Jun 2019
Cited by 24 | Viewed by 4439
Abstract
Calcium phosphate cements (CPC) and mesoporous bioactive glasses (MBG) are two degradable biomaterial groups widely under investigation concerning their applicability to treat bone defects. MBG-CPC composites were recently shown to possess enhanced degradation properties in comparison to pure CPC. In addition, modification of [...] Read more.
Calcium phosphate cements (CPC) and mesoporous bioactive glasses (MBG) are two degradable biomaterial groups widely under investigation concerning their applicability to treat bone defects. MBG-CPC composites were recently shown to possess enhanced degradation properties in comparison to pure CPC. In addition, modification of MBG allows an easy incorporation of therapeutically effective ions. Additive manufacturing of such composites enables the fabrication of patient-specific geometries with further improved degradation behavior due to control over macroporosity. In this study, we developed composites prepared from a non-aqueous carrier-liquid (cl) based CPC paste and MBG particles suitable for extrusion-based additive manufacturing (3D plotting). CPC with the addition of up to 10 wt % MBG were processible by adjusting the amount of cl. Scaffolds consisting of a 4, 6 and 8%-MBG-CPC composite were successfully manufactured by 3D plotting. While mechanically characterization of the scaffolds showed an influence of the MBG, no changes of microstructure were observed. During degradation of the composite, the release of Ca2+ and Sr2+ ions could be controlled by the MBG composition and plotted scaffolds with macropores showed a significant higher release than bulk samples of comparable mass. These findings demonstrate a high flexibility regarding ion release of the developed composites and suggest utilizing the drug binding capacities of MBG as a prospective delivery system for biologically active proteins. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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15 pages, 7193 KiB  
Article
Effect of Baghdadite Substitution on the Physicochemical Properties of Brushite Cements
by Young Jung No, Ib Holzmeister, Zufu Lu, Shubham Prajapati, Jeffrey Shi, Uwe Gbureck and Hala Zreiqat
Materials 2019, 12(10), 1719; https://doi.org/10.3390/ma12101719 - 27 May 2019
Cited by 16 | Viewed by 4854
Abstract
Brushite cements have been clinically used for irregular bone defect filling applications, and various strategies have been previously reported to modify and improve their physicochemical properties such as strength and injectability. However, strategies to address other limitations of brushite cements such as low [...] Read more.
Brushite cements have been clinically used for irregular bone defect filling applications, and various strategies have been previously reported to modify and improve their physicochemical properties such as strength and injectability. However, strategies to address other limitations of brushite cements such as low radiopacity or acidity without negatively impacting mechanical strength have not yet been reported. In this study, we report the effect of substituting the beta-tricalcium phosphate reactant in brushite cement with baghdadite (Ca3ZrSi2O9), a bioactive zirconium-doped calcium silicate ceramic, at various concentrations (0, 5, 10, 20, 30, 50, and 100 wt%) on the properties of the final brushite cement product. X-ray diffraction profiles indicate the dissolution of baghdadite during the cement reaction, without affecting the crystal structure of the precipitated brushite. EDX analysis shows that calcium is homogeneously distributed within the cement matrix, while zirconium and silicon form cluster-like aggregates with sizes ranging from few microns to more than 50 µm. X-ray images and µ-CT analysis indicate enhanced radiopacity with increased incorporation of baghdadite into brushite cement, with nearly a doubling of the aluminium equivalent thickness at 50 wt% baghdadite substitution. At the same time, compressive strength of brushite cement increased from 12.9 ± 3.1 MPa to 21.1 ± 4.1 MPa with 10 wt% baghdadite substitution. Culture medium conditioned with powdered brushite cement approached closer to physiological pH values when the cement is incorporated with increasing amounts of baghdadite (pH = 6.47 for pure brushite, pH = 7.02 for brushite with 20 wt% baghdadite substitution). Baghdadite substitution also influenced the ionic content in the culture medium, and subsequently affected the proliferative activity of primary human osteoblasts in vitro. This study indicates that baghdadite is a beneficial additive to enhance the radiopacity, mechanical performance and cytocompatibility of brushite cements. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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12 pages, 2600 KiB  
Article
The Addition of Poly(Vinyl Alcohol) Fibers to Apatitic Calcium Phosphate Cement Can Improve Its Toughness
by Jun Luo, Julien Faivre, Håkan Engqvist and Cecilia Persson
Materials 2019, 12(9), 1531; https://doi.org/10.3390/ma12091531 - 10 May 2019
Cited by 11 | Viewed by 3928
Abstract
Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications. The aim of the [...] Read more.
Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications. The aim of the current study was to improve the toughness of hydroxyapatite cements through fiber reinforcement. The effect of the addition of hydrophilic, poly(vinyl-alcohol) (PVA) fibers to hydroxyapatite cement was evaluated in terms of mechanical properties, including compressive strength, diametral tensile strength and toughness (work of fracture), as well as setting time, phase composition and cement morphology. The fiber reinforcement enhanced the fracture resistance of the hydroxyapatite cement, but also simultaneously reduced the compressive strength and setting time of the cements. However, cement with 5 wt % of fibers (of the powder component) could be considered a good compromise, with a compressive strength of 46.5 ± 4.6 MPa (compared to 62.3 ± 12.8 MPa of that without fibers), i.e., still much greater than that of human trabecular bone (0.1–14 MPa). A significantly higher diametral tensile strength (9.2 ± 0.4 MPa) was found for this cement compared to that without fibers (7.4 ± 1.5 MPa). The work of fracture increased four times to 9.1 ± 1.5 kJ/m2 in comparison to the pristine apatite. In summary, the hydroxyapatite cements could be reinforced by suitable amounts of PVA fibers, which resulted in enhancing the material’s structural integrity and ductility, and increased the material’s resistance to cracking. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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18 pages, 9499 KiB  
Article
Biomechanical Evaluation of Promising Different Bone Substitutes in a Clinically Relevant Test Set-Up
by Theresa Brueckner, Philipp Heilig, Martin Cornelius Jordan, Mila Marie Paul, Torsten Blunk, Rainer Heribert Meffert, Uwe Gbureck and Stefanie Hoelscher-Doht
Materials 2019, 12(9), 1364; https://doi.org/10.3390/ma12091364 - 26 Apr 2019
Cited by 20 | Viewed by 4516
Abstract
(1) Background: Bone substitutes are essential in orthopaedic surgery to fill up large bone defects. Thus, the aim of the study was to compare diverse bone fillers biomechanically to each other in a clinical-relevant test set-up and to detect differences in stability and [...] Read more.
(1) Background: Bone substitutes are essential in orthopaedic surgery to fill up large bone defects. Thus, the aim of the study was to compare diverse bone fillers biomechanically to each other in a clinical-relevant test set-up and to detect differences in stability and handling for clinical use. (2) Methods: This study combined compressive strength tests and screw pullout-tests with dynamic tests of bone substitutes in a clinical-relevant biomechanical fracture model. Beyond well-established bone fillers (ChronOSTM Inject and Graftys® Quickset), two newly designed bone substitutes, a magnesium phosphate cement (MPC) and a drillable hydrogel reinforced calcium phosphate cement (CPC), were investigated. (3) Results: The drillable CPC revealed a comparable displacement of the fracture and maximum load to its commercial counterpart (Graftys® Quickset) in the clinically relevant biomechanical model, even though compressive strength and screw pullout force were higher using Graftys®. (4) Conclusions: The in-house-prepared cement allowed unproblematic drilling after replenishment without a negative influence on the stability. A new, promising bone substitute is the MPC, which showed the best overall results of all four cement types in the pure material tests (highest compressive strength and screw pullout force) as well as in the clinically relevant fracture model (lowest displacement and highest maximum load). The low viscosity enabled a very effective interdigitation to the spongiosa and a complete filling up of the defect, resulting in this demonstrated high stability. In conclusion, the two in-house-developed bone fillers revealed overall good results and are budding new developments for clinical use. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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14 pages, 28100 KiB  
Article
Prefabricated and Self-Setting Cement Laminates
by Theresa Brückner, Andreas Fuchs, Laura Wistlich, Andreas Hoess, Berthold Nies and Uwe Gbureck
Materials 2019, 12(5), 834; https://doi.org/10.3390/ma12050834 - 12 Mar 2019
Cited by 6 | Viewed by 3936
Abstract
Polycaprolactone (PCL) fiber mats with defined pore architecture were shown to provide sufficient support for a premixed calcium phosphate cement (CPC) paste to serve as a flat and flexible composite material for the potential application in 2-dimensional, curved cranial defects. Fiber mats were [...] Read more.
Polycaprolactone (PCL) fiber mats with defined pore architecture were shown to provide sufficient support for a premixed calcium phosphate cement (CPC) paste to serve as a flat and flexible composite material for the potential application in 2-dimensional, curved cranial defects. Fiber mats were fabricated by either melt electrospinning writing (MEW) or solution electrospinning (SES) with a patterned collector. While MEW processed fiber mats led to a deterioration of the cement bending strength by approximately 50%, due to a low fiber volume content in conjunction with a weak fiber-matrix interface, fiber mats obtained by solution electrospinning resulted in a mechanical reinforcement of the cement matrix in terms of both bending strength and absorbed fracture energy. This was attributed to a higher fiber volume content and a large contact area between nanosized fibers and cement matrix. Hydrophilization of the PCL scaffolds prior to lamination further improved composite strength and preserved the comparably higher fracture energy of 1.5 to 2.0 mJ/mm2. The laminate composite approach from this study was successful in demonstrating the limitations and design options of such novel composite materials. However, fiber-cement compatibility remains an issue to be addressed, since a high degree of hydrophilicity does not necessarily provoke a stronger interface. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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20 pages, 6501 KiB  
Article
Tough and Elastic α-Tricalcium Phosphate Cement Composites with Degradable PEG-Based Cross-Linker
by Michaela Rödel, Jörg Teßmar, Jürgen Groll and Uwe Gbureck
Materials 2019, 12(1), 53; https://doi.org/10.3390/ma12010053 - 24 Dec 2018
Cited by 6 | Viewed by 4448
Abstract
Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based [...] Read more.
Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we describe the synthesis of suitable triblock degradable poly(ethylene glycol)-poly(lactide) (PEG-PLLA) cross-linker to improve the resorption capacity of such composites. A study with four different formulations was established. As reference, pure hydroxyapatite (HA) cements and composites with 40 wt% HEMA in the liquid cement phase were produced. Furthermore, HEMA was modified with 10 wt% of PEG-PLLA cross-linker or a test series containing only 25% cross-linker was chosen for composites with a fully degradable polymeric phase. Hence, we developed suitable systems with increased elasticity and 5–6 times higher toughness values in comparison to pure inorganic cement matrix. Furthermore, conversion rate from α-tricalcium phosphate (α-TCP) to HA was still about 90% for all composite formulations, whereas crystal size decreased. Based on this material development and advancement for a dual setting system, we managed to overcome the drawback of brittleness for pure calcium phosphate cements. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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8 pages, 4851 KiB  
Article
Photoluminescent Eu3+-Doped Calcium Phosphate Bone Cement and Its Mechanical Properties
by Annemarie Oesterle, Anne V. Boehm and Frank A. Müller
Materials 2018, 11(9), 1610; https://doi.org/10.3390/ma11091610 - 4 Sep 2018
Cited by 5 | Viewed by 3762
Abstract
Calcium phosphate cements (CPC) are well-established bone replacement materials that have been used in dentistry and orthopedics for more than 25 years. The monitoring of bone cements and the associated healing processes in the human body is difficult and so far has often [...] Read more.
Calcium phosphate cements (CPC) are well-established bone replacement materials that have been used in dentistry and orthopedics for more than 25 years. The monitoring of bone cements and the associated healing processes in the human body is difficult and so far has often been achieved using cytotoxic X-ray contrast agent additives. These additives have a negative effect on the mechanical properties and setting time of the bone cement. In this paper, we present a novel approach to prepare contrastive CPC by the incorporation of luminescent Eu3+-doped hydroxyapatite (Eu:HAp) nanoparticles. Eu-doped CPC (Eu:CPC) exhibited enhanced mechanical properties compared to pure CPC. Furthermore, the red photoluminescence of Eu:CPC may allow the observation of CPC-related healing processes without the use of harmful ionizing radiation. Full article
(This article belongs to the Special Issue Mineral Bone Cements: Current Status and Future Prospects)
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