Calcium phosphate bioceramics research in Latvia

Calcium phosphate bioceramics including glass-ceramics and hydroxyapatite h ave been manufactured and investigated for implantation purposes. Three gla ss systems were selected based on CaO and P2O5 and an inert metal oxide (ei ther Ta2O5, TiO2 or Nb2O5). Different compositions were found giving crysta l phases in a glassy matrix. These glass-ceramics were tested for strength with 4-point bending, and the biocompatibility ascertained using in vitro a nd in vivo tests. The Nb2O5 containing glass-ceramic showed bone apposition and was found to be a suitable material for implantation. Hydroxyapatite w as produced using the wet method and it was found that the pH during the re action and the dispersivity of the Ca(OH)(2) influence the purity of the po wder. The pH was controlled by addition of ammonium hydroxide to the precip itate. Hydroxyapatite sprayed onto grit blasted titanium showed low strengt hs of 20-30 MPa with adhesive failure but was increased to 60-70 MPa with a n intermediate glass layer. Composites of glass-ceramic with hydroxyapatite exhibited a higher strength than hydroxyapatite with a value of 100-120 MP a. (C) 1999 Elsevier Science Limited and Techna S.r.l. All rights reserved.