Tailoring brushite for in situ setting bone cements

Current strategies in developing calcium phosphate bone substitutes are focused towards in situ setting of the cements under physiological conditions with adequate mechanical properties, which can be tailored to be resorbable by controlling structure and composition. In this study we report the formulation of brushite cements at both physiological and ambient temperature and its effect on the structure and properties. In addition the influence of using both, an alkaline and acidic retardant on the setting and ageing of the cements are reported. Monosodium citrate (pH 3.5 ± 0.1) or trisodium citrate (pH 8.3 ± 0.1) solutions were used at retardants at 23 °C and 37 °C, which clearly indicated that both these parameters influenced strength and microstructure. The ageing of the cements indicated some conversion to monetite, which was predominant in cements formulated at physiological temperature. The results clearly show that the microstructure, resorbability and strength of these in situ setting cements can be manipulated by compositional and temperature ranges to provide wider application as bone substitute materials.