P-31 Solid-State NMR Study of the Chemical Setting Process of a Dual-Paste Injectable Brushite Cements

The composition and evolution of a brushite-type calcium phosphate cement was investigated by Solid-State NMR and X-ray during the setting process. The cement is obtained by mixing beta-tricalcium phosphate [Ca-3(PO4)(2), beta-TCP] and monocalcium phosphate monohydrate [Ca(H2PO4)(2)center dot H2O, MCPM] in presence of water, with formation of dicalcium phosphate dihydrate or brushite [CaHPO2 center dot 2H(2)O, DCPD]. Analysis of the initial beta-TCP paste has shown the presence of beta-calcium pyrophosphate [Ca2P2O7, beta-CPy] and that of the initial MCPM a mixture of MCPM and dicalcium phosphate [CaHPO4, DCP]. Follow-up of the chemical composition by P-31 Solid-State NMR enables to show that the chemical setting process appeared to reach an end after 20 min. The constant composition observed at the end of the process was similarly determined. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 91 B: 46-54, 2009