ABSTRACT
Objective:To investigate the effect of different plasticizers on the compressive strength of injectable calcium sulfate cement (ICSC).Methods:Hydroxymethylcellulose (CMC), methylcellulose (MC), hyaluronic acid (HA), stearic acid (SA) and self-made hemihydrate calcium sulfate were used to mix them, and the compressive strength of the complex was observed after reaction with normal saline; the changes of ICSC's own properties, such as setting time and injectability, were recorded.Results:The compressive strength of calcium sulfate was 21±4.58 mPa, and the final setting time was 3.86 ± 0.09 min. Different concentrations of SA had no significant effect on the compressive strength of calcium sulfate ( F=1.593, P=0.266), but prolonged the setting time ( F=29.868, P=0.000). CMC with different concentrations significantly reduced the compressive strength of calcium sulfate ( F=23.943, P=0.000), and the setting time was prolonged to more than 120 min. Different concentrations of MC can improve the compressive strength of calcium sulfate ( F=4.808, P=0.034), and prolong the setting time ( F=191.192, P=0.000); among them, 1% and 3% MC can significantly improve the compressive strength ( P=0.007, 0.027). Different concentrations of HA can improve the compressive strength ( F=3.818, P=0.058), and prolong the setting time ( F=262.515, P=0.000), of which 3% and 5% were significantly improved ( P=0.026, 0.015), while 1% group was not significantly improved ( P=0.062). In addition, the injectable properties of HA, MC, stearic acid and CMC are better, respectively. Conclusion:SA and CMC can not be used to improve the compressive strength of calcium sulfate, while HA and MC of appropriate concentration can improve the compressive strength of ICSC, and improve the injectable performance, but MC can make the coagulation time more in line with clinical needs.
ABSTRACT
Bioactive glasses (BGs) are a kind of biomaterials with osteoconductive and osteoinductive properties and are able to create a strong bond with host bone and promote osteogenesis after implantation. According to their compositions, bioactive glasses can be classified as silicate BGs, phosphate BGs, and borate BGs. Nowadays, silicate BGs are still the most common, while phosphate BGs and borate BGs have higher dissolution and degradation rates. Melt?quenching and sol?gel process are two basic methods to produce melt?derived BGs and sol?gel BGs, respectively. The latter requires lower heat treatment temperature with higher specific surface area and biological activity. Bioactive glass?ceramics can be obtained by heat treatment, which improves the mechanical strength but slightly reduces the bioactivity. Nano?bioactive glasses with the higher specific surface area can be ob?tained by changing the structure size of the materials by other treatment methods. On this basis, 3D BGs scaffolds can be made, and hybrid BGs scaffolds as well by combining with other biomaterials to obtain the 3D interconnected pores with the hierarchical or bionic structures, to enhance the mechanical strength, osteogenic activity and provide mechanical support suitable for the host bone. However, the bioactivity of BGs depends on the degradation rate, to some extent, which is contradictory to the mechanical strength. An appropriate porosity or controllable degradation rate can be selected to meet the common needs of early support and osteogenesis. In basic studies, it was found that BGs could act on cells by releasing ions or through the macropinocytosis pathway, up?regulating the expression of related genes or promoting osteogenesis. The degradation rates of BGs are related to their struc?tures and compositions, which enables the quantitative prediction of the change of mechanical strength during degradation. Prog?ress has also been made in structural mechanics and testing methods.