Characterization of the novel calcium phosphate/sulfate based bone cements

Calcium phosphate cements (CPCs) are a family of self-setting, bone repair materials. CPCs possess excellent biocompatibility, surgical handiness and adequate mechanical properties but reveal slow resorption in vivo. Currently, very interesting group of CPCs are biomaterials composed of a-tricalcium phosphate (a-TCP, a-Ca3(PO4)2) and calcium sulfate. Calcium sulfate hemihydrate (CSH, CaSO40.5 H2O) posses a long clinical history in different fields of medicine and is widely recognized as a safe, fast setting and resorbable implant material. The main goal of this study was to investigate how different factors influence the phase composition and physico-chemical properties of the new, cement-type material on the basis of a-TCP, CSH and anhydrous dicalcium phosphate (DCP, CaHPO4). In presented work two different powder phase compositions and three liquid phases were used to produce new bone substitutes. XRD results showed that obtained materials, after setting and hardening, consisted of α-TCP, DCP, DCPD (CaHPO42H2O), HA and bassanite phases. Initial (I) and final (F) setting times of the cement pastes were determined with Gillmore needles and differed in the range of 4-14 min (I) and 10-30 min (F). Increase in the amount of CSH in the powder component resulted in shortening of setting time. Microstructure of cements was evaluated on the fractured samples by scanning electron microscopy (SEM) and the porosity via mercury porosimetry. Open porosity of the final materials was similar for all investigated compositions. Compressive strength depended on the composition and increased steadily over a period of maturation. The results obtained suggest that calcium phosphate/sulfate bone cement has the potential to be applied for bone augmentation.