Setting Time Of Calcium Phosphate Cement Research Articles

Improving osteogenesis of calcium phosphate bone cement by incorporating with manganese doped β-tricalcium phosphate.

Lack of osteogenic capacity limits the bone repair effect of calcium phosphate cement (CPC). In present work, bivalent manganese ion (Mn2+) doped β-tricalcium phosphate (Mn-TCP) was incorporated into CPC to enhance its osteogenic ability. The incorporation of Mn-TCP promoted the hydration reaction of CPC. The presence of Mn2+ made the hydration products finer. When adding 10wt% Mn-TCP in CPC (Mn-CPC-1), the setting time of CPC was shortened, whereas the strength and injectability were not changed. Mouse Bone marrow mesenchymal stem cells (mBMSCs) on Mn-CPC-1 and CPC with 20wt% Mn-TCP (Mn-CPC-2) presented better adhesion and spreading behaviors. Besides, Mn-CPC-1 promoted the gene levels of ALP, Col-I and OC while Mn-CPC-2 promoted the gene levels of Runx2 and OC. Cellular behaviors were related to two points: one was the increase of adsorption capacity of proteins (e.g. BSA) after changing the surface properties of bone cements; and the other was the biological role of Mn2+ released from CPC in osteogenesis. All the results indicated that CPC incorporated with 10wt% Mn-TCP has good osteogenesis and proper physicochemical properties, which will be a prospective biomaterial applying in the area of bone regeneration.

Effect of methotrexate on the mechanical properties and microstructure of calcium phosphate cement.

Calcium phosphate cement (CPC) is widely used as an antitumor bone-filling material. Methotrexate (MTX) is recognized as an effective chemotherapy medicine. The current study examined the effects of MTX on the mechanical properties and microstructure of CPC. Methotrexate-loaded CPC at mass ratios of 0%, 0.1%, 0.2%, and 0.5% were designated as groups A, B, C, and D, respectively, and were pressed into precast cylindrical molds. Solidification time, axial compressive strength, transverse compressive strength, and rotational tensile strength were measured, and scanning electron microscopy images were captured before and after MTX-CPC microstructure changes occurred. Average initial and final setting times increased gradually with increasing drug concentration, but this increase was not significant among the groups. Average axial transverse compressive strength and rotational tensile strength of groups B and C were not significantly different from those of group A (P>.05); however, there was a significant difference in these properties between groups A and D (P<.05). Scanning electron microscopy observations showed a porous crystalline structure. The addition of MTX to CPC does not significantly affect the basic crystal structure and setting time of CPC. Adding MTX at mass ratios of 0.1% and 0.2% to CPC does not lead to a significant difference in mechanical strength and can therefore be applied in clinical practice. This study may shed some light on the future application of MTX-loaded CPC in the treatment of bone defects after tumor excision.

Microstructure and properties of alendronate-loaded calcium phosphate cement

Calcium phosphate cement (CPC), as an injectable bone substitute material is significant in bone defect treatment. Drugs and biological molecules are often incorporated into CPC to promote the healing of bone defects and treat some bone diseases. In this work, alendronate (ALN)-loaded CPC was prepared and the influences of the content of ALN on the setting time, microstructure of hydrate porosity, mechanical strength, in vitro drug release, rheological properties and injectability of CPC were systematically investigated. The results showed that the addition of ALN had no effect on the final hydration product of CPC. The setting time of CPC was prolonged, while the prolonging effect became weak when the larger amount of ALN was added. With the increment of ALN content, the hydroxyapatite crystals of cured CPC became smaller, and the hydrated CPC became more compact with lower porosity, which resulted in the improvement of compressive strength of CPC with a drug-loaded amount less than 1wt%. The injectability was dramatically improved due to the addition of ALN, which was corresponding to the decrease of viscosity. The thixotropy of the CPC slurry was promoted with increasing the ALN content, which could enhance the stability of the slurry. However, it was worth noting that an inverted thixotropic loop appeared when the drug content was higher than 3.0wt%. During the in vitro drug release, the initial burst release turned up for all formulations and the degree of burst release was different from each other. This work would allow advances in understanding the effect of ALN on the setting process and physical and chemical properties of CPC, and we should think over the appropriate content when adding ALN into CPC.

Effect of Silk Fibroin on the Properties of Calcium Phosphate Cement

To improve the physicochemical properties of calcium phosphate cement (CPC), silk fibroin (SF) in the different forms were added into CPC. The structure of the composites was studied by X-ray diffraction. The setting time was investigated by ISO Cement Standard Consistency Instrument. Scanning Electron Microscope was used to observe the surface morphology. Mechanical properties of samples were tested by Instron Universal Testing Machine. The results indicated that acicular crystal of hydroxyapatite (HA) was formed in the hardening body of both CPC with SF and the pure CPC. Addition of SF had no significant effect on the structure of SF/CPC composite. The setting time of CPC with SF was significantly shorter than that of the pure CPC (30.3 mins). The setting time of CPC by adding silk fibroin powder I (SFP) and silk fibroin fiber (SFF) was greatly shortened, which was only 11.7 minutes. The setting time of CPC with SFP decreased approximately by 1/3, while the setting time of the CPC with SFF decreased nearly by 1/2. With the adding of SF, the compressive strength of CPC increased significantly. There was a distinct increase in the work-of-compressive of CPC with the adding of SFF.

Physicochemical properties of TTCP/DCPA system cement formed in physiological saline solution and its cytotoxicity

In this paper, the physicochemical properties and cytotoxicity of calcium phosphate cement (CPC), prepared by mixing cement powders of tetracalcium phosphate (TTCP) and dicalcium phosphate (DCPA) with a cement liquid of physiological saline solution, were investigated. The microstructure evolution of various hardened cement bodies and their hydration crystals as a function of immersion time in similar physiological fluids, physiological saline solution (0.9% NaCl), or simulated body fluids (SBF), were also studied. Results show that the setting time of CPC is in the range of 12-15 min, which meets the clinical application demands. We also found that the mean compressive strength of the CPC samples immersed in SBF for 3 days is 104+/-10 MPa which reaches the transverse compressive strength, 106-133 MPa, of human long bone. The results obtained from both the X-ray powder diffraction analyses (XRD) and scanning electron microscopy (SEM) observations indicated that a reinforcing effect of some remaining TTCP particles in the early stages of immersion is mainly responsible for the increase in the initial strength. Although the CPC failed to keep this high level when immersed for a longer time, the initial reinforcing effect of the remaining TTCP particles provides advantages for clinical applications. This would be effective when the material is loaded at the very beginning of the implantation, especially for the material used as a fixation, which requires a certain initial strength in the early stages of the implantation. The cytotoxicity results showed that the relative growth rate (RGR%) of L929 cells on the CPC samples using physiological saline solution as a cement liquid was slightly superior to that of the samples using the 0.5 mol/L phosphate acid solution as the cement liquid. This was most likely caused by the pH difference between the two CPC samples immersed in a DMEM-BFS medium.