Abstract
Bone-grafts are needed to fill bone defects like bone cavities, and for replacement of diseased or injured bones; and autografts or allografts have up until recently been the only option despite problems like; pain, limited availability and immunogenicity. Synthetic bone replacements have gathered widespread research and industrial attention (like the JRI hip replacement) due to obvious autoimmune advantages, and biomaterials like calcium phosphates have demonstrated promising results in various biomedical applications as alternatives for hard-tissue replacement because of their resemblance with the mineral constituent of the bone. In this study calcium phosphate or hydroxyapatite (HA) with different Ca/P ratios (1.00, 1.33, 1.50, 1.67 and 2.00) were precipitated by a new precipitation method using Tris-HCl buffer. Powders were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). XRD studies of the unheated powders indicate the presence of single-phase HA for all the experimental ratios (1.33, 1.50, 1.67and 2.00). Heating the powders at 850 oC, resulted in the formation of âtricalcium phosphate (â-TCP) which was very obvious in the Ca/P ratios lower than 1.67. SEM of the powder (Ca/P ratio of 1.67) shows particles with plate-like morphology. Heterogeneous granules comprising of spherical and irregularshaped granules were obtained by mixing with an impeller while adding water and rolling the container and by use of glass beads.

Key words: Bone-graft, Calcium phosphate, Hydroxyapatite, Tissue engineering, Biomaterials