Injectable biphasic calcium phosphate bone cements (BCPCs) composed of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) have been intensively investigated because of their high rate of biodegradation, bioactivity and osteoconductivity, which can be adjusted by changing the ratio between β-TCP and HA phases after setting. The aim of this study was to evaluate the performance of 1 wt% chitosan fiber additive with biphasic calcium phosphate as an injectable bone cement both in vitro and in vivo. In vitro evaluation of compressive strength, degradation rate, morphology, and cell and alkaline phosphatase activities was done by comparison with bone cement without β-TCP. The in vivo results for micro-CT scanning and histological examinations for three groups (control, BCPC and commercial biphasic calcium phosphate granules) were characterized and compared. After the addition of 20 wt% β-TCP to calcium phosphate cement, the initial and final setting times of the sample were 3.92 min and 11.46 min, respectively, which were not significantly different from cement without β-TCP. The degradation time of the BCPC material was longer than that of calcium phosphate cement alone. The healing process was significantly faster for BCPC than for the control and commercial product groups. Therefore, this is the first evidence that BCPC is an attractive option for bone surgery due to its faster stimulation of healing and faster degradation rate.

This study has investigated the effect of combination of new liquid phase mixture of disodium hydrogen phosphate (Na 2 HPO 4 ) and polyacrylic acid (PAA) on the compressive strength, setting time, bioactivity, and cytotoxicity of biphasic calcium phosphate cement. The PAA was known as one of water-soluble and biocompatible polymers to improve the mechanical performances of the bone cement, but it usually inhibits the phase conversion to hydroxyapatite after the cement has already set.The aim of this work was to evaluate the incorporation of the mixture of PAA and Na 2 HPO 4 into biphasic cement. We have found the crucial concentration for adding PAA/Na 2 HPO 4 at 30:70 v/v% to enhance the mechanical strength, cell viability, and maintain bioactivity. The phase composition and crosslinking reaction between PAA and alpha-tricalcium phosphate (α-TCP) powder were detected by XRD and FTIR techniques. The beta-tricalcium phosphate (β-TCP) was added in the formula to achieve the biphasic cement, which composed of β-TCP and apatite/calcium deficient-hydroxyapatite (CD-HA) in the final product. The biphasic granule commercial product was used as comparison in the cell viability test. This work had been confirmed that the cement was a nontoxic material. Therefore, our results suggest that the PAA/Na 2 HPO 4 could be beneficial for further clinical applications. K E Y W O R D Sbiopolymer, bone cement, calcium phosphate cement, polyacrylic acid, polymeric cement

Natural rubber compound (NRC) was blended with biodegradable poly(butylene succinate) (PBS) with PBS/NRC weight ratios of 100/0, 97/3, 94/6 and 90/10. The PBS/NRC blends were melt mixed using an internal mixer at 145°C. Mechanical properties and melt flow index of the blends were investigated. The results showed that the percentage elogation at break and impact strength of the blends impoved when NRC was added. On the other hand, the Young’s modulus and tensile strength of the blends decreased with an increase in the amount of NRC. The melt flow index of the blends continuously decreased with an increase in NRC content. This implied that NRC increased the viscosity of the blends. Moreover, the fractured surface morphology of PBS/NRC blends showed a good dispersion of NRC particles in PBS matrix. The average particle size of NRC was 2-5 μm.

Apatite wollastonite glass ceramic (AW-GC) (34.2% SiO2, 44.9% CaO, 16.3%P2O5, 4.6% MgO, 0.5% CaF2) was added into a brushite bone cement, which composed of β-tricalcium phosphate (β-Ca3(PO4)2, β-TCP) and monocalcium phosphate monohydrate (Ca (H2PO4)2H2O, MCPM) in powder phases. Cement was prepared using a 3 β-TCP:2 MCPM in weight ratio. To evaluate the effect of AW-GC on the mechanical strength and degradability of brushite bone cement, the powder phases and 1 wt.% of chitosan dissolved in 5 wt.% of citric acid solution were mixed and soaked in simulated body fluid solution at 37 °C for 1, 3, 5,7 and 14 days, respectively. The compressive strength and setting time of AW-GC added in brushite bone cement were studied and compared with pure brushite cement. The pH values increased with addition of AW-GC. Additionally, the obtained brushite bone cements were characterized by XRD, SEM techniques.