In vitro biological effects of titanium rough surface obtained by calcium phosphate grid blasting

Surface roughness modulates the osseointegration of orthopaedic and dental titanium implants. High surface roughness are currently obtained by blasting of titanium implants with silica or aluminium oxide abrasive particles. This process may cause the release of cytotoxic silicium or aluminium ions in the peri-implant tissue. To generate a biocompatible roughened titanium surface, we currently develop an innovative grid-blasting process using biphasic calcium phosphate (BCP) particles. Titanium alloy (Ti6Al4V) discs were either polished, BCP grid-blasted or left as-machined. BCP grid-blasting created an average surface roughness of 1.57 +/- 0.07 microm compared to the original machined surface of 0.58 +/- 0.05 microm. X-ray photoelectron spectroscopy indicated traces of calcium and phosphorus and relatively less aluminium on the BCP grid-blasted surface than on the initial titanium specimen. Scanning electronic microscopy observations and measurement of mitochondrial activity (MTS assay) showed that osteoblastic MC3T3-E1 cells were viable in contact with the BCP grid-blasted titanium surface. In addition, our results indicate that MC3T3-E1 cells expressed ALP activity and conserved their responsiveness to bone morphogenetic protein BMP-2. The overall results clearly indicate that this calcium phosphate grid-blasting technique increases the roughness of titanium implants and provides a non-cytotoxic surface with regard to mouse osteoblasts.