Mechanical Properties and In Vitro Bioactivity of Ca5(PO4)2SiO4 Bioceramic

Abstract

Pure Ca5(PO4)2SiO4 bioceramic was first prepared by a sol–gel method using triethyl phosphate, tetraethoxysilane, and calcium nitrate tetrahydrate as original materials. Simulated body fluid (SBF) immersion tests revealed that Ca5(PO4)2SiO4 samples had a greater in vitro apatite-forming ability than hydroxyapatite (HA). After soaking Ca5(PO4)2SiO4 samples in the SBF for 1 day, bone-like apatite precipitated on the surfaces and the apatite layer became thicker with increasing the soaking time. However, few bone-like apatites precipitated on the HA samples even after soaking in the SBF for 7 days. The good in vitro bioactivity of Ca5(PO4)2SiO4 samples was attributed to the silanol (Si-OH) groups and greater solubility of Ca5(PO4)2SiO4. In addition, hot-pressed Ca5(PO4)2SiO4 ceramic exhibited lower bending strength and elastic modulus than hot-pressed HA, since the former had a lower relative density than the latter. The results have shown that Ca5(PO4)2SiO4 is a potential candidate material for bone repair.