Low toxicity of dissolved silver from silver-coated titanium dental implants to human primary osteoblast cells

The controlled release of silver as a biocide from Ag-coated medical implants is desirable. However, the biocompatibility of Ag leachates is poorly understood. This study investigated the toxicity of silver released from the silver plated titanium implants to human primary osteoblast cells; and the effect of cell culture medium on the silver speciation and bioavailability.

METHODS: Ti6Al4V discs were coated with Ag nanoparticles (NPs), silver plus hydroxyapatite (HA) nanoparticles (Ag+nHA), or Ag NPs plus microparticles (Ag+mHA). Primary human osteoblast cells were exposed to the leachates from the various discs for up to 7 days.

RESULTS: the total Ag concentrations released as leachate from the silver-plated titanium discs were 0.7-1.6 mg L -1, regardless of treatment. Cumulative silver release over 7 days was approximately 3 mg L -1 in all treatments. The concentration of total Ag in the cell homogenates from all the Ag-containing treatments was modest, ∼ 0.1 µg mg protein -1 or less at day 7. Cells showed normal healthy morphology with no appreciable leak of LDH or ALP activity into the external media compared to the reference control. Similarly, there was no significant differences (Kruskal Wallis, p > 0.05) in the LDH or ALP activity in the cell homogenate between treatments.

CONCLUSIONS: overall, there was a controlled release of Ag into the external media, but this remained biocompatible with no deleterious effects on the osteoblast cells, which means that the released silver to the peri-implant environment is not toxic making the coating potential for clinical use.