Biocompatibility of silver and hydroxyapatite antimicrobial nanocoatings on titanium alloy dental implants with human gingival fibroblasts

OBJECTIVES: Peri-implantitis compromises soft and hard tissues around dental implants, often leading to implant failure. Antibacterial nanocoatings offer a promising infection control strategy, but maintaining biocompatibility is essential. This study investigated, through a range of assays and analytical techniques, the biocompatibility of antimicrobial silver and hydroxyapatite (HA) nanocoatings applied to titanium implants with human gingival fibroblasts (HGFs).

METHODS: Silver and hydroxyapatite nanocoatings were applied to the surface of titanium alloy specimens using electroplating, deposition and sintering techniques. The biocompatibility of the nanocoatings with HGFs was assessed by measuring cell metabolic activity (alamarBlue), lactate dehydrogenase (LDH) release, collagen production (Sircol assay), and cell morphology (scanning electron microscopy). Nanocoating stability was tested in ultrapure water, Modified Krebs and artificial saliva.

RESULTS: Elevated total Ag+ concentrations were measured in the media released from the silver and HA nanocoatings (1.78 mg/l on day 4 and 1 mg/l by day 7). Electrolytes remained within physiological ranges. The HGFs cultured on the nanocoatings showed normal morphology, intact membranes (LDH < 60 nmol/min/ml), healthy collagen secretion (27.18 - 31.11 µg/ml), and aerobic metabolism at 80% of controls, consistent with biocompatibility.

SIGNIFICANCE: The silver and HA nanocoatings confirmed a sustained Ag+ release, necessary for a strong antimicrobial activity, while maintaining HGFs health and cell functionality. Our previous work has confirmed the strong antimicrobial activity of these nanocoatings when applied to dental implants, and the findings of this study have demonstrated that the implant biocompatibility is not compromised. This suggests that these silver and HA nanocoatings can be safely used to minimise peri-implantitis and prevent implant failure.