In vitro characterization of a zinc based bioceramic.

Six different blends of zinc calcium phosphorous oxide ceramics (ZCAP) were prepared by mixing and calcining powders (ZnO:CaO:P2O5) of weight percent ratio: 50:30:20, 48:32:20, 44:20:26, 40:40:20, 30:40:30, and 30:30:40. ZCAP is a resorbable bioceramic and has been used to repair bone defects and deliver drugs in a continuous manner. The chemical composition, porosity, and elements released on exposure to buffered Tris HCl were measured for each blend of ZCAP. The products of mixing and thermal reaction were beta-Ca3(PO4)2, alpha-CaZn2(PO4)2, and 2CaO.P2O5. Free calcium and/or zinc oxide was present in several blends. The components of ZCAP and their volume percentages influenced the interconnected porosity of ZCAP bioceramics. The interconnected porosity for all blends of ZCAP ranged from 35 to 38%. Pore sizes from these six blends of ZCAP ranged from less 1 micron to greater than 100 microns. Results of the 12 hour dissolution study showed that more calcium was released than zinc or phosphorous from all blends of ZCAP. Zinc was released in trace amounts from all blends of ZCAP. Release of phosphorous from the different blends of ZCAP was not detected by the procedures used to detect phosphorous in this investigation. These blends of ZCAP have the potential to be used as bone substitutes and probably long term treatment of zinc deficiency in humans.