Setting reactions involved in injectable cements based on amorphous calcium phosphate

alpha -BSM (R) (bone substitute material) is an injectable cement constituted by a mixture of dicalcium phosphate dihydrate (DCPD, 50%) and amorphous calcium phosphate (ACP, 50%). The setting reaction is due to the fast hydrolysis of the amorphous phase into apatite. DCPD acts as a template, which facilitates apatite nucleation and growth and converts slowly into apatite in a second step. Unlike most other ionic cement, the setting reaction needs warmth to begin and develop. The paste does not harden at room temperature, but only at body temperature. The final product is a nanocrystalline apatite with a low Ca/P atomic ratio (1.45) and a high content of hydrogenophosphate ions and non-apatitic environments. These characteristics create highly bioactive, fast resorbable Ca-P cement, close to bone mineral.