Physico-chemical and biological properties of novel Eu-doped carbonization modified tricalcium silicate composite bone cement

This paper introduces a novel composite bone cement (Eu:HAp/V-C₃S), which is composed of carbonated tricalcium silicate (V-C₃S) and europium-doped hydroxyapatite (Eu:HAp), and Eu:HAp was generated by hydrothermal synthesis. The physical and chemical properties, mineralization in vitro, biocompatibility and bacteriostasis of the composite bone cement were evaluated. The results show that the Eu:HAp/V-C₃S composite bone cement has good setting properties and a relatively low pH value. The composite bone cement with 0.1 wt% Eu has a higher compressive strength than pure V-C₃S (141.06% higher than pure V-C₃S), which can greatly improve the mechanical properties of the materials. The in vitro immersion test shows that composite bone cement has good mineralization ability. The cell test proves that it has good cell proliferation ability and low cytotoxicity. In addition, the bacteriostatic experiment also verifies that composite bone cement has bacteriostatic effect to some degree. These results indicate that Eu:HAp/V-C₃S composite bone cement is a promising biomedical material.     

Fast setting tricalcium silicate/magnesium phosphate premixed cement for root canal filling

MTA-based root-end filling is a promising therapeutic approach for root repair, however, difficult handling characteristics, presence of toxic elements in the material composition and long setting time are main drawbacks for clinical applications. The purpose of this study was to develop a novel fast setting silicate based premixed cement for endodontic use. The premixed cement contained tricalcium silicate (C3S) as the main constituent for hydration, magnesium phosphate cement (MPC) as setting accelerators and glycerol as water-miscible liquid. The physicochemical properties and antibacterial property of the novel cements were evaluated. Moreover, biocompatible zirconium oxide (ZrO₂) was chosen as radiopacifying agent added into the premixed cement. The radiopacity, physicochemical properties, antibacterial property and cytotoxicity of the radiopaque premixed calcium silicate based cements were evaluated. The setting time of the premixed MPC/C3S cements could be modulated within the range from 70 min to 205 min by adjusting the content of MPC. Meanwhile, the premixed MPC/C3S cement displayed good flowability and injectability when the amount of MPC less than 20%. The addition of ZrO₂ provided the premixed MPC/C3S cement with excellent radiopacity while had no significant effects on the setting time, flowability, film thickness, injectability and washout resistance. Moreover, the premixed cement with or without ZrO₂ had good antibacterial property and cytotoxicity. Our results indicated that the premixed MPC/C3S/ZrO₂ cement could be considered as a promising candidate for application in endodontics owing to its desirable physicochemical properties, antibacterial activity and cytocompatibility, especially relatively short setting time and good sealing ability.     

Fast-setting and high fracture toughness Ce-TZP/tricalcium silicate composite dental cement

For dental materials, a certain defect tolerance would be beneficial. Some Ceria-stabilized zirconia (Ce-TZP) composites are promising dental repair materials, as they have been shown to exhibit an obvious amount of transformation-induced plasticity with almost no dispersion in strength data. The purpose of this study was to design a novel tricalcium silicate (C₃S)-based dental repair material by adding 10 mol.% Ce-TZP to improve fracture toughness and dipotassium hydrogen phosphate (K₂HPO₄) as the setting accelerator. The study evaluated the physicochemical properties, in vitro cell activity, and antibacterial activity of Ce-TZP/C₃S composite cement, and the results revealed that Ce-TZP/C₃S cement showed a fast-setting ability and good washout resistance when the setting time was controlled within 26–43 min. With increasing Ce-TZP content, the mechanical properties, especially the flexural strength and fracture toughness, were gradually enhanced. Additionally, the 30% Ce-TZP/C₃S composite showed good antibacterial activity and in vitro cytocompatibility. The study concluded that 30% Ce-TZP/C₃S composites could be regarded as ideal candidates in the field of dental materials due to their excellent physical and chemical properties, antimicrobial activity, in vitro cytocompatibility, outstanding fracture toughness and fast-setting ability.     

Hydroxyapatite/tricalcium silicate composites cement derived from novel two-step sol-gel process with good biocompatibility and applications as bone cement and potential coating materials

Tricalcium silicate (C₃S) and hydroxyapatite (HAp) composites were fabricated through the sol-gel process. The aim of this research is to improve the biocompatibility of C₃S through HAp addition and study the potential of using this as coating materials. The composites (HAp/C₃S) were characterised by Fourier transform infrared spectrometry, thermal gravity-differential thermal analysis and X-ray diffraction. The working and setting times of cement pastes were tested using Gillmore needle. Mechanical properties were examined by nanoindentation and material testing system. In vitro biocompatibility of the materials were studied by cell attachment and viability of L929 and MG-63 cells. HAp/C₃S as a coating material on gelatin film were measured with the surface roughness and imaged by scanning electron microscope. With the addition of HAp, no undesirable free CaO was detected with the synthesis by the sol-gel preparation. The pH values of HAp added groups were between 7.54 and 8.76, which were much lower than pure C₃S group (pH?=?11.75). For in vitro studies, the presence of HAp could effectively enhance the cell attachment and viability of both L929 and MG-63 cells grown in the extract or directly on the composites. However, the mechanical properties of the composites were impaired as compared to pure C₃S. Lastly, HAp/C₃S cement could be evenly coated on gelatin film. HAp is successfully demonstrated to improve C₃S biocompatibility with this new composites HAp/C₃S. C-75 (75% C₃S and 25% HAp), in particular, has good biocompatibility, relatively high compressive strength and can be uniformly coated onto gelatin film. Thus, C-75 is a promising material for further investigation as a coating on other biopolymers.     

Physicochemical and biological properties of composite bone cement based on octacalcium phosphate and tricalcium silicate

Biocompatible tricalcium silicate (C₃S) bone cement is widely used as dental and bone repair material; however, its long setting time, poor injectability and low initial mechanical properties limit clinical applications. In order to improve C₃S silicate bone cement and its derivatives to play a more important role in tooth restoration, bone defect repair, implant coating and tissue engineering scaffolds, a novel C₃S and octacalcium phosphate (OCP) composite bone cement (OCP/C₃S) was prepared and evaluated for setting time, injectability, anti-flocculation, pH, microstructure, bioactivity and cytotoxicity. The setting time of the OCP/C₃S composite bone cement was controlled within the clinically operable time range (8.3–13.7 min); the cement exhibited good compressive strength, injectability (93.54%), and anti-collapse performance. The 20% OCP/C₃S composite bone cement had a compressive strength of 28.94 MPa, 93% stronger than pure C₃S (14.98 MPa). An in vitro immersion test showed that the composite bone cement had excellent hydroxyapatite forming ability, proper degradation rate, and a low pH value. Cellular experiments confirmed the low cytotoxicity of the composite bone cement and its great capacity for cell proliferation. These results indicate that 20% OCP/C₃S composite bone cement is a promising biomaterial.     

The effect of tricalcium silicate incorporation on bioactivity,injectability, and mechanical properties of calcium sulfate/bioactive glass bone cement

The conventional Polymethyl methacrylate (PMMA) bone cement is not biodegradable and not bioactive to bond with the native bone and causes tissue necrosis resulting from its high exothermic polymerization. Hence, biodegradable bioactive bone cements with suitable setting time and mechanical properties should be introduced. In this study, novel bioactive bone cements containing Calcium Sulfate Hemihydrate (CSH), Bioactive Glass (BG), and Tricalcium Silicate (TSC) were developed. Firstly, CSH and BG binary system was optimized based on preliminary setting and mechanical tests. Secondly, the composite bioactive bone cements were obtained by adding different quantities of TCS to the optimized CS-BG (1.3:1 wt % ratio) system. All groups exhibited desirable handling properties, an initial setting time of lower than 15 min, injectability of greater than 85%, and controlled degradability. Moreover, they demonstrated initial compressive strength values of higher than 12 MPa, superior to trabecular bone. After 28 days of hydration, the compressive strength of the cement containing 30% TCS reached 51.04 MPa. Furthermore, the present bone cements showed favorable bioactivity and bone-bonding ability as a result of calcium carbonate and hydroxyapatite (HA) formation. Furthermore, this novel bone cement exhibited appropriate biocompatibility and mesenchymal stem cell attachment, suggesting its potential for clinical applications.     

纳米SiO_2对硅酸三钙基骨水泥性能的影响

研究纳米SiO2对硅酸三钙(Ca3SiO5,简称C3S)基骨水泥性能的影响。结果表明:纳米SiO2的掺入,可以加快C3S的水化进程,但延缓了浆体的凝结。纳米SiO2与Ca(OH)2反应生成较低n(Ca)/n(Si)的CSH凝胶,降低了固化体中Ca(OH)2的含量。纳米SiO2与Ca(OH)2反应生成的CSH凝胶呈网络交织状结构,既可对固化体起到密实填充作用,又可增强固化体的胶凝性能,从而提高固化体的力学性能。固化体中Ca(OH)2的含量随纳米SiO2掺入量增加而降低;当SiO2掺入量达到6%时,固化体中CSH凝胶的平均n(Ca)/n(Si)开始降低。     

Effects of decalcification on the microstructure and surface area of cement and tricalcium silicate pastes

Thin coupons of white portland cement (WPC) and tricalcium silicate paste were decalcified by leaching in concentrated ammonium nitrate solutions, resulting in calcium-to-silicon molar ratios (C/S) ranging from 3.0 (control) down to 0.3. The microstructure and surface area were measured using both small-angle neutron scattering (SANS) and nitrogen gas sorption. The intensity in the SANS data regime corresponding to the volume fractal C-S-H gel phase increased significantly on leaching, and the total surface area per unit specimen volume measured by SANS doubled on leaching from C/S=3.0 to near C/S=1.0. The nitrogen BET surface area of the WPC pastes, expressed in the same units, increased on decalcification as well, although not as sharply. The primary cause of these changes is a transformation of the high-density “inner product” C-S-H gel, which normally has a low specific surface area as measured by SANS and nitrogen gas sorption, into a morphology with a high specific surface area. The volume fractal exponent corresponding to the C-S-H gel phase decreased with decalcification from 2.3 to 2.0, indicating that the equiaxed 5 nm C-S-H globule building blocks that form the volume fractal microstructure of normal, unleached cement paste are transformed by decalcification into sheetlike structures of increasing thickness.     

In vitro bonelike apatite formation on magnetite nanoparticles after a calcium silicate treatment: Preparation,characterization and hemolysis studies

Bioactive magnetite nanoparticles were prepared successfully by coating magnetite nanoparticles with CaSiO₃ followed by their immersion in simulated body fluid. The Fe₃O₄ nanoparticles (5–10 nm) were synthesized by a co-precipitation technique. In order to prepare core–shell nanocomposites, the nanoparticles were soaked for 1 h in a calcium silicate solution that had been aged for 24 h before using it. The samples were dried in air and then immersed in SBF at 37 °C for 1, 3 and 7 days. The analyses of the samples after the biomimetic process revealed the formation of a bonelike apatite layer on all the samples tested and not a significant change was observed on their original magnetic behavior. Hemolysis test, evaluated as release of hemoglobin, revealed that all the samples showed no hemolytic effects up to 3 mg/ml, indicating no damage of the red blood cell membranes. These bioactive, hemocompatible and superparamagnetic particles may be potential materials for bone cancer treatment by hyperthermia.