Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates

Metallic calcium was never used before as the calcium source in synthesizing bioceramics. Amorphous calcium phosphate (ACP) powders were synthesized at room temperature, in synthetic mineralization solutions which contained Na+, K+, Mg2+, Cl-, HCO3- and HPO42- ions at concentrations similar to those found in human blood plasma, by using calcium (Ca) metal as the only calcium source. The experimental conditions leading to the formation of PCA (cryptocrystalline or poorly crystallized apatite) or CaCO3 powders were also determined when using metallic Ca in aqueous synthesis in the mineralization solutions. The formation of calcium phosphate (Car') in synthesis solutions was immediately initiated by the addition of calcium metal granules (or shots), at appropriate amounts, into the solutions while the solutions were being continuously stirred in glass bottles at room temperature (22 +/- 1 degrees C). The synthesis reactions were reaching completion in less than 30 min with the final solution pH values ranging from 9 to 12, without a necessity for any external pH adjustment in the form of any strong base (such as NH4OH, LiOH, NaOH or KOH) additions. ACP or PCA powders are useful for dentin and enamel re-mineralization applications or orthopedic (bone) defect-filling applications. (C) 2012 Elsevier B.V. All rights reserved.