Osteoblastic cell behaviour on different titanium implant surfaces

The osseointegration of oral implants is related to the early interactions between osteoblastic cells and titanium surfaces. The behaviour of osteoblastic MC3T3-E1 cells was compared on four different titanium surfaces: mirror-polished (Smooth-Ti), alumina grit-blasted (Alumina–Ti) or biphasic calcium phosphate ceramic grit-blasted (BCP–Ti) and a commercially available implant surface (SLA). Scanning electron microscopy and profilometry showed distinct microtopographies. The BCP–Ti group had higher average surface roughness (R_a = 2.5 μm) than the other grit-blasted groups. Hydrophilicity and surfaces energies were determined on the different substrates by dynamic contact angle measurements. The most hydrophilic surface was the Alumina–Ti discs, while SLA was the most hydrophobic. The titanium surfaces were all oxidized as TiO₂ and polluted by carbon contaminants, as determined by X-ray photoelectron spectroscopy. Alumina–Ti samples also exhibited aluminium peaks as a result of the blasting. The BCP–Ti discs contained traces of calcium and phosphorus. MC3T3-E1 cells attached, spread and proliferated on the substrates. For both the SLA and BCP–Ti groups, the entire surface was covered with a layer of osteoblastic cells after 2 days. At high magnification, the cells exhibited cytoplasmic extensions and filopodia. Compared with plastic, cell viability was similar with the Smooth–Ti, slightly lower with the Alumina–Ti and superior with the SLA and BCP–Ti groups. Alkaline phosphatase activity increased with the culture time whatever the substrate. This study shows that BCP-blasting produces rough titanium implants without surface contaminants.