Effects of spherical tetracalcium phosphate on injectability and basic properties of apatitic cement

Although injectability through syringe is one of the key advantages of apatite cement (AC), injectability of current AC is not satisfactory for its clinical use. In this investigation, therefore, effects of powder shape on injectability were studied using spherical tetracalcium phosphate (s-TTCP) prepared with plasma melting method. Bulk density of AC using s-TTCP (s-AC) showed larger value than AC using irregular TTCP (i-TTCP) (i-AC). Also we found better injectability when we used s-TTCP. However, diametral tensile strength of set s-AC was significantly lower than i-AC. X-ray powder diffraction analysis revealed limited transformation to apatite in the case of set s-AC. To avoid the drawback due to plasma melting method, s-TTCP was again heated to 1500 degree for four hours and quenched to room temperature (q-TTCP). AC using q-TTCP (q-AC) transformed to apatitic mineral and showed the similar DTS value with i-AC. We concluded, therefore, spherical powder is very useful to improve the injectability of AC. Also, we found re-heat treatment of TTCP is useful if s-TTCP is prepared using plasma melting method.