Calcium phosphate cement (CPC) comes as a powder and after mixing it wit water hardens in situ to form hydroxyapatite and is used in dental and craniofacial restorative applications. It consists equimolar amounts of ground Ca4(PO4)2O (tetracalcium phosphate, TTCP) and CaHPO4 (dicalcium phosphate anhydrous, DCPA).

Further readings:
1) http://www.scientific.net/Calcium+Phosphate+Cement+(CPC):+A+Critical+Development+Path.html
2) http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=9663744&dopt=AbstractPlus
3) http://www.blackwell-synergy.com/doi/abs/10.1111/j.1551-2916.2006.01460.x?journalCode=jace

Guy