Biocompatibility and adhesion of silver nano-coating on titanium dental implants
Objectives: To investigate the adhesion of silver and hydroxyapatite nanocoatings applied to the surface of titanium dental implants; and then to determine the biocompatibility of the coated dental implants with osteoblast cells.
Methods: Ti6Al4V discs were polished and coated with silver nanoparticles (Ag), silver and hydroxyapatite nanoparticles (Ag+nHA) or microparticles (Ag+mHA). The silver and HA coatings were applied using the electroplating and sintering techniques respectively and then examined by electron microscopy. The adhesion of these coatings was measured by a pull-off test according to BS EN ISO 4624:2003 using an Instron 5582 series. The biocompatibility of the coatings was tested with primary human osteoblasts in 24-well microplates (n=9). Cell viability was assessed using the alamar blue assay, lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activities over 7 days. The cell morphology was investigated using scanning electron microscopy (SEM). Ag, Ca, P in the media and cell electrolyte (Na+, K+) concentrations were measured using inductively coupled plasma atomic emission spectroscopy (ICP-OES).
Results: SEM and energy dispersive X-ray spectroscopy (EDS) confirmed that Ti6Al4V discs were successfully coated. Results of pull-off test showed that the adhesion between the coatings and titanium substrate is firm and able to withstand at least 6 Mpa. The findings of the alamar blue assay revealed that all Ag coated discs caused 35% reduction in cell viability, also LDH showed the similar result. ALP activity was below detection limit or slightly higher. SEM images showed that the osteoblast cells on Ag+nHA are healthier and have a better contact than those on Ag and Ag+mHA though less confluent than the control.
Conclusions: Coatings were successfully applied to the substrate and demonstrated an acceptable adhesion. All Ag coated discs can reduce cell viability but Ag+nHA exhibited a better biocompatibility than Ag and Ag+mHA ones.