Brushite Cement Research Articles

Eggshell derived brushite bone cement with minimal inflammatory response and higher osteoconductive potential.

Brushite cements are known for excellent osteoconductive and degradation properties, however, its widespread use is limited due to rapid setting time and poor mechanical properties. The eggshell derived calcium phosphates exhibits improved physical and biological properties due to the presence of biologically relevant ions. In this study, eggshell derived brushite cement (EB) was fabricated using β-tricalcium phosphate synthesized from eggshells. The presence of trace elements in EB prolonged its setting time. The size of brushite crystals in EB was found to be smaller than the pure brushite cement (PB) leading to increased initial compressive strength and higher in vitro degradation rate. The L6 and MG63 cell lines exhibited good biocompatibility with the cement at the end 72 h. In vivo studies of the cements were performed in rat calvarial defect model. Micro CT analysis showed faster degradation and accelerated bone formation in EB filled defect. Histological studies revealed infiltration of inflammatory cells into the implant site for both the cements till 6th week. However, inflammation was found to be significantly reduced at the 12th week in EB compared to PB leading to complete bone bridge formation. Multi-ion substituted EB seems to be a potential bone substitute material with a reasonable setting time for ease of handling, higher mechanical strength, minimal inflammatory response and higher bone regeneration.

Injectable dicalcium phosphate bone cement prepared from biphasic calcium phosphate extracted from lamb bone

Quick setting and poor injectability due to liquid–solid phase separation have limited the clinical use of brushite and monetite cements. The presence of certain ions in the cement during the setting reaction moderate the setting time and properties of the cement. This study reports the preparation of injectable bone cement by using biphasic calcium phosphate (BCP) extracted from femur lamb bone by calcination at 1450 °C. EDX analysis infers the presence of Mg and Na ions as trace elements in BCP. X-ray diffraction patterns of the prepared cement confirmed the formation of brushite (DCPD) along with monetite (DCPA) as a minor phase. DCPA phase diminished gradually with a decrease in powder to liquid ratio (PLR). Initial and final setting time of 5.3 ± 0.5 and 14.67 ± 0.5 min respectively are obtained and within the acceptable recommended range for orthopedic applications. Exceptional injectability of ≈90% is achieved for all prepared bone cement samples. A decrease in compressive strength was observed with increase in the liquid phase of the cement, which is attributed to the higher degree of porosity in the set cement. Immersion of bone cement in simulated body fluid (SBF) for up to 7 days resulted in the formation of apatite layer on the surface of cement with Ca/P ratio 1.71, which enhanced the compressive strength from 2.88 to 9.15 MPa. The results demonstrate that bone cement produced from BCP extracted from femur lamb bone can be considered as potential bone substitute for regeneration and repair of bone defects.

Brushite cement containing gelatin: evaluation of mechanical strength and in vitro degradation

Abstract Calcium phosphate cements (CPCs) are potential materials for repairing bone defects, mainly due to their excellent biocompatibility and osteoconductivity. Nevertheless, their low mechanical properties limit their usage in clinical applications. The gelatin addition may improve the mechanical and biological properties of CPCs, but their solubility in water may increase the porosity of the cement during degradation. Thus, the aim of this work was to investigate the influence of gelatin on the setting time, compressive strength and degradation rate of a brushite cement. CPCs were prepared with the addition of 0, 5, 10 and 20 wt% of gelatin powder in the solid phase of the cement. The results indicated that the setting time increased with gelatin. Furthermore, cement with 20 wt% of gelatin had an initial compressive strength of 14.1±1.8 MPa while cement without gelatin had 4.5±1.2 MPa. The weight loss, morphology and compressive strength were evaluated after degradation in Ringer’s solution. According to the weight loss data, gelatin was eliminated of samples during degradation. It was concluded that the presence of gelatin improved CPCs mechanical properties; however, as degradation in Ringer’s solution evolved, cement compressive strength decreased due to gelatin dissolution and, consequently, an increase in sample porosity.

Fabrication of alginate modified brushite cement impregnated with antibiotic: Mechanical, thermal, and biological characterizations

Treatment of postsurgical infections, associated with orthopedic surgeries, has been a major concern for orthopedics. Several strategies including systematic and local administration of antibiotics have been proposed to this regard. The present work focused on fabricating alginate (Alg) modified brushite (Bru) cements, which could address osteogeneration and local antibiotic demands. To find the proper method of drug incorporation, Gentamicin sulfate (Gen) was loaded into the samples in the form of solution or powder. Several characterization tests including compression test, morphology, cytotoxicity, and cell adhesion assays were carried out to determine the proper concentration of Alg as a modifier of the Bru cement. The results indicated that addition of 1 wt% Alg led to superior mechanical and biological properties of the cement. Moreover, Alg addition changed the morphology of the cement from plate and needle-like structures to petal-like structure. Fourier transform infrared spectroscopy results confirmed the successful loading of Gen on the cements, specifically when Gen solution was used, and X-Ray Diffractometer result indicated that Gen caused a decrease in crystalline size. Furthermore, thermal analysis revealed that Gen-loaded sample had more stable structure as the transformation temperature slightly shifted to a higher one. The stability study confirmed the chemical stability and adequate mechanical performance of the cements within 1 month of soaking time. Finally, the addition of Alg has a positive impact on the release behavior at low concentration of Gen solution so that 20% decrease within 2 weeks of release experiment was remarkably detected.

Effect of Baghdadite Substitution on the Physicochemical Properties of Brushite Cements.

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.

In vitro and in vivo evaluation of bioglass microspheres incorporated brushite cement for bone regeneration

Bioglass-calcium phosphate cement (CPC) composite materials have recently received increased attention for bone regeneration purposes, owing to their improved properties in term of biocompatibility and bone ingrowths. In this study, an injectable bone substitute (IBS) system which utilizes bioglass microspheres incorporated into brushite based cement, was evaluated. The microspheres were synthesized with a simple and low sintering temperature process; there was no significant phase difference shown from the powder and good interactivity with cells was obtained. Furthermore, physical properties were optimized in microsphere incorporated brushite cement in order to investigate in vitro and in vivo performance. Accordingly, setting time and compressive strength were hardly altered until a microsphere content of 40% (v/v) was reached. The brushite (BR)/bioglass microsphere (BM) system showed excellent bioactivity to the in-vitro simulated body fluid test: dissolution ions from composite materials influenced apatite growth, countered acidic pH, and increased material degradation. In an in-vitro study with preosteoblasts (MC3T3-E1), BR/BM supported cell adhesion and proliferation, while cell differentiation experiments without osteogenic supplements, demonstrated that BR/BM induced osteogenic differentiation. A post-implantation study conducted in femoral defects showed higher materials degradation and bone formation in BR/BM than in BR. The faster dissolution of bioglass microspheres increased BR/BM composite resorption and hence facilitated bone tissue integration. Our findings suggest that bioglass microspheres incorporated in cement could potentially be used as an injectable bone substitute for bone regeneration applications.

Preparation of brushite cements with improved properties by adding graphene oxide.

Background: Brushite (dicalcium phosphate dihydrate, DCPD) cement as a promising bioactive material for bone tissue engineering is widely used to treat defects. However, relatively poor mechanical properties of brushite cement limit its application in loadbearing conditions. The aim of this study is to investigate the effect of graphene oxide (GO) addition to the physical-mechanical-biological properties of brushite cement.Methods: The brushite types of cement were prepared by mixing β-tricalcium phosphate [β-TCP, Ca3 (PO4)2] and monocalcium phosphate monohydrate [MCPM, Ca(H2PO4)2. H2O]. GO was introduced at 0, 0.5, 2, and 5 wt.% with the liquid. MG63 cells were cultured on the GO/CPC surfaces to observe various cellular activities and hydroxyapatite (HA) mineralization.Results: Based on our results, GO/CPC composites exhibit improvement in compressive strength compared to pure CPC. New Ca-deficient apatite layer was deposited on the composite surface after immersing immersion in SBF for 7 and 14 days. Field emission scanning electron microscope (FESEM) images indicated that pure and GO incorporated brushite cement facilitates cell adhesion. CPC/GO was slightly toxic to cells such that high concentrations of GO decreased the cell viability. Besides, alkaline phosphatase (ALP) activity of cells was improved compared with the pure CPC.Conclusion: Our results highlight the role of graphene oxide that may have great potential in enabling the utility of graphene-based materials in various biomedical applications.

Accelerated Transformation of Brushite Cement into Carbonate Apatite in Biomimetic Solution

Brushite cement has advantages such as fast setting, high reactivity and good injectability over apatitic cements. To induce the bioactivity of brushite cements, the goal was to convert it into a bone-like low crystalline carbonate apatite. To achieve this induced transformation, potassium and magnesium were used as dopants which were claimed to be effective in the literature. The cements were immersed for 2 periods of time: 1 day and 6 weeks in Tas-Simulated-Body-Fluid (Tas-SBF) due to its excellent biomimetic properties with its adjusted HCO3- and Cl- ionic rates according to human-blood-plasma. 5% of potassium (to calcium sites) seemed to be more effective over magnesium modification. The aim of this study is to define an optimal composition in terms of transforming brushite into apatite.

Investigation of Brushite Cement Based on α-Tricalcium Phosphate and Its Composite with Polylactic Framework

Brushite cement based on alpha-tricalcium phosphate (α-TCP) and its composite with polylactide (PL) frame with a Kelvin structure were developed. The composite was obtained by filling the PL frame with liquid cement paste by extrusion. A 30% aqueous solution of magnesium dihydrogen phosphate was used as a cement liquid. The cement phase composition was studied before soaking in a physiological solution: the main phases are dicalcium phosphate dihydrate (DCPD), tricalcium phosphate, and amorphous calcium phosphate. It was found that magnesium does not form a separate phase but, probably, is a part of a DCPD crystal lattice. During soaking of cement in a physiological solution, two processes occur simultaneously, namely, the release of calcium ions into the solution, mostly through the dissolution DCPD, and the precipitation of calcium ions from the solution on the cement surface in the form of apatite, which is confirmed by the data of X-ray phase analysis and microstructure studies. After the exposure in a physiological solution, the apatite phase becomes the main phase and the DCPD content decreases, which is related to the transformation of DCPD into the apatite phase. The solubility was studied in a physiological solution containing a Tris buffer. In the absence of a buffer, the solution pH increased and, as a result, the solubility of the composite increased too. In the presence of a buffer, the solubilities of cement and composite varied insignificantly.

Synergistic Effects of Silicon/Zinc Doped Brushite and Silk Scaffolding in Augmenting the Osteogenic and Angiogenic Potential of Composite Biomimetic Bone Grafts.

Cell instructive scaffolding platforms displaying synergistic effects by virtue of their chemical and physical cues have tremendous scope in modulating cell phenotype and thus improving the success of any graft. In this regard, we report here the development of Si- and Zn-doped brushite cement composited with silk scaffolding that hierarchically emulated the cancellous bone. The composite scaffolds fabricated exhibited an open porous network capable of enhanced osteoblast survival as attested by increased alkaline phosphatase activity and also sustaining osteoclast activity affirmed by tartrate resistant acid phosphatase staining. Moreover, the chemical cues presented by dissolutions products from the composite scaffold enabled the osteoblasts to secrete proangiogenic factors which favored better endothelial cell survival, confirmed through in vitro experiments. Moreover, the efficacy of these composite biomimetic scaffolds was validated in vivo in volumetric femur defects in rabbits, which revealed that these matrices influenced vascular cell infiltration and favored the formation of matured bony plate. Fluorochrome labeling studies and microtomography analysis revealed that at the end of three months, the implanted composite scaffolds had completely resorbed, leaving behind neo-osseous tissue and vouching for clinical translation of these composite matrices as viable and affordable bone-graft substitutes.

Improved Injection Behavior with the Addition of Granulated β-Tricalcium Phosphate in Brushite Bone Cement

To improve the injection behavior of brushite cement, dense β-Ca3(PO4)2 (β-TCP) granules were added to the starting material. The spherical β-TCP granules prepared by spray-drying and subsequent sintering at 1000 ~ 1200°C accounted for fractions of from 0.5 to 0.7 of the total β-TCP. The injection behavior was evaluated by measuring the injected mass divided by the loaded mass of paste in the syringe pump. The injected amount was increased with the increase in the fraction and sintering temperature of β-TCP granules, except at 1200°C. The increase in the fraction of β-TCP and its sintering temperature resulted in a decrease in the plastic limit, which is the volume of water required to liquefy the compact. The rest water could be utilized in the cement with the reduced plastic limit for improved injectability. The amounts of rest water assigned for powdery phase were estimated, and correlated with the injectability of paste. Key words: Bone cement, β-TCP Granule, Injection, Plastic limit, Granular fraction

Effects of Cobalt on Physical and Mechanical Properties and In Vitro Degradation Behavior of Brushite Cement

Cobalt (Co), a vital element in biological functions, induces osteogenesis and angiogenesis at low concentrations. We present the effects of Co and its concentration on the setting time, compressive strength, and degradation behavior of brushite cement (BrC), a potential candidate to fill small bone defects. Addition of Co at up to 1 wt.% decreased the compressive strength in a dose-dependent manner to 1.09 ± 0.21 MPa. The initial setting time decreased in samples with 0.25 wt.% Co from 3.67 ± 0.23 min to 2.21 ± 0.04 min, then increased to 6.80 ± 0.08 min with addition of 1 wt.% cobalt, while a similar trend was found for the final setting time. The stable pH of the buffer during degradation along with phase analysis showing presence of only tricalcium phosphate and dicalcium phosphate dihydrate suggest that the disintegration of the cement is not accompanied by any noticeable chemical reaction. These data show that, although Co significantly affects the setting time and compressive strength, it does not play a critical role in the degradation behavior of BrC.

A ready-to-use acidic, brushite-forming calcium phosphate cement

Premixed calcium phosphate cements have been developed to simplify the usage of traditional calcium phosphate cements and reduce the influence of the setting reaction on the delivery process. However, difficulties in achieving a good cohesion, adequate shelf life and sufficient mechanical properties have so far impeded their use in clinical applications, especially for the more degradable acidic calcium phosphate cements.In this study, a brushite cement was developed from a series of ready-to-use calcium phosphate pastes. The brushite cement paste was formed via mixing of a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with good injectability and adequate shelf life. The MCPM paste was based on a water-immiscible liquid with two surfactants and the β-TCP paste on a sodium hyaluronate aqueous solution. The effect of citric acid as a retardant was assessed. Formulations with suitable amounts of citric acid showed good cohesion and mechanical performance with potential for future clinical applications. Statement of SignificanceAcidic calcium phosphate cements have attracted extensive attention as bone substitute materials due to their ability to resorb faster than basic calcium phosphate cements in vivo. However, traditionally, short working times and low mechanical strength have limited their clinical application. Premixed cements could simplify the clinical use as well as improve property reproducibility, but short shelf lives, low cohesion and low mechanical properties have restricted the development.In this study, an injectable ready-to-use two-phase system consisting of an MCPM paste and a β-TCP paste was developed based on acidic cement. It shows good cohesion, compressive strength and adequate shelf life, which has the potential to be used in a dual chamber system for simplified and fast filling of bone defects in a minimally invasive manner. This will reduce surgery time, decrease the risk of contamination and ensure repeatable results.

Highly flexible and degradable dual setting systems based on PEG-hydrogels and brushite cement

With respect to the composition of natural bone, we established a degradable dual setting system of different poly(ethylene glycol) (PEG)-based hydrogels combined with a brushite cement. The idea was to reinforce the inorganic calcium phosphate mineral phase with an organic, polymeric phase to alter the cement’s properties towards ductility and elasticity. Extremely flexible samples were produced via this dual setting approach with a fully reversible elasticity of the samples containing high molecular weight PEG-based hydrogel precursors. Using the decalcifying agent EDTA, the whole inorganic phase was dissolved due to Ca2+-complexation and dimensionally stable hydrogels were obtained, indicating a homogenous polymeric phase within the composites. This was also confirmed by SEM-analysis, where no discontinuities or agglomerations of the phase were observed. Additional XRD-measurements proved a significant influence of the coherent polymeric matrix on the conversion from β-TCP/MCPA to brushite with a decrease in signal intensity. The results confirmed a parallelly running process of setting reaction and gelation without an inhibition of the conversion to brushite and the formation of interpenetrating networks of hydrogel and cement. The strengths of this newly developed dual setting system are based on the material degradability as well as flexibility, which can be a promising tool for bone regeneration applications in non-load bearing craniomaxillofacial defects. Statement of SignificanceBrushite based calcium phosphate cements (CPCs) are known as bone replacement materials, which degrade in vivo and are replaced by native bone. However, the pure inorganic material shows a brittle fracture behavior. Here, the addition of a polymeric phase can influence the mechanical properties to create more ductile and flexible materials. This polymeric phase should ideally form during cement setting by a polymerization reaction to achieve high polymer loads without altering cement viscosity and it should be degradable in vivo similar to the cement itself. Therefore, we developed a dual setting system based on simultaneous cement setting of brushite and lactide modified poly(ethylene glycol) dimethacrylate (PEG-PLLA-DMA)-based hydrogel. It was evident that the gels form a continuous phase within the cement after radical polymerization with a strong reduction of cement brittleness.

Synthesis and evaluation of a collagen–brushite cement as a drug delivery system

Abstract Calcium phosphate cements are known for their biocompatibility and bioactivity, which has led to a significant increase in their use. They have the advantage of being prepared as a malleable paste that sets in a few minutes and can be easily applied in bone defects. In this research work, 6 brushite cement formulations were prepared and the effect of collagen addition and the release of tetracycline were evaluated. All cements gave a malleable paste that set in 2 or 3 min, resulting in a material with pores of 5–20 μm. The cements showed compression resistance values between 0.8 and 1.7 MPa, and the addition of collagen was the most influential factor in the increase of this property. Up to 40 % of the drug was released after 7 days and the effectiveness of its antimicrobial activity was confirmed.

Setting and hardening process of a wollastonite-based brushite cement

Wollastonite-based brushite cements are used for refractory material applications, but they may also offer prospects for the solidification/stabilization of hazardous waste. These binders are formed by the reaction of wollastonite with an orthophosphoric acid solution containing borax and metallic cations (Al3+, Zn2+). This work provides new insights into their setting and hardening process using a panel of characterization techniques (XRD, NMR, rheology…). A multi-step hydration process is evidenced by the formation of several products: amorphous silica, monocalcium phosphate monohydrate (Ca(H2PO4)2·H2O or MCPM), that precipitates transiently during the first stage of hydration, and brushite (CaHPO4·2H2O) that crystallizes at higher pH (≥3). In addition, an amorphous phosphate phase containing aluminum, calcium and zinc massively precipitates at the beginning of hydration, and gets richer in calcium as hydration progresses. Setting of the cement paste occurs when brushite starts to form. The successive formation of MCPM and brushite is well predicted by thermodynamic modelling.

Reinforcement of Brushite Cement Based on α-TCP by Rigid Polylactide Framework

Brushite cement obtained from α-Ca3(PO4)2 and orthophosphoric acid in the presence of Mg(H2PO4)2 with compressive strength of 18 MPa was armored with a framework with the Kelvin architecture made of polylactide by thermoextrusion 3D printing. It is shown that armoring of cement with polylactide framework allows one not only to increase the compressive strength of such a structure (up to 35 MPa) but also to significantly improve its deformability (up to 15%).

Исследование брушитового цемента на основе альфа-трикальцийфосфата и его композита с полилактидным каркасом

Исследование брушитового цемента на основе альфа-трикальцийфосфата и его композита с полилактидным каркасом

Fe-doped brushite bone cements with antibacterial property

In present research, Fe-doped brushite bone cements were synthesized. The setting time, microstructure and antibacterial property of samples were investigated. The results showed that the setting time of cements was retarded to about 20 min and 123 min, respectively, as iron doping content increasing from 1 mol% to 5 mol% in β-TCP powder. Moreover, Fe-doped cements had much bigger crystal particles and calcium iron phosphate was identified in them. Furthermore, Fe-doped cements performed well in inhibiting the growth of Staphylococcus aureus and Pseudomonas aeruginosa, and larger inhibition halo was obtained with more iron content. Nevertheless, the Fe-loaded cements were not so sensitive to Escherichia coli as to the other two bacteria.

Effects of platelet-rich plasma on biological activity and bone regeneration of brushite-based calcium phosphate cement.

In this study, we focused on identifying the effects of platelet-rich plasma (PRP) on bioactivity and bone ingrowths incorporated into brushite cement. We introduced PRP as a series of substitutions with an aqueous citrate-ion solution, and the optimized cement with PRP showed no disintegration of the paste consistency. Incorporating PRP showed that the setting time decreased with the increasing of PRP ratios, although the compressive strength was not significantly changed. We evaluated in vitro degradation and bioactivity with the simulated body fluid test, and the result showed that adding PRP accelerated the carbonated apatite nucleation and markedly improved the surface reactivity of the cement. The in vitro studies demonstrated that incorporating PRP into the brushite cement improved cell adhesion and proliferation. The in vivo effects of PRP were faster degradation, improved tissue response in the early stage, and bone ingrowths. We demonstrated based on our results of this study, incorporation of PRP into brushite cement could be helpful for improving biological activity of the cement as well as bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2316-2326, 2018.