Macroporous coating of silver-doped hydroxyapatite/silica nanocomposite on dental implants by EDTA intermediate to improve osteogenesis, antibacterial, and corrosion behavior

Coating a titanium (Ti) implant with hydroxyapatite (HA) increases its bioactivity and biocompatibility. However, implant-related infections and biological corrosion have restricted the success of implant. To address these issues, a modified HA nanocomposite (HA/silica-EDTA-AgNPs nanocomposite) was proposed to take advantage of the sustained release of silver nanoparticles (AgNPs) and silicate ions through the silica-EDTA chelating network. As a result, a uniform layer of nanocomposite, compared to HA as the gold standard, was formed on Ti implants without fracture and with a high level of adhesion, using plasma electrolytic oxidation (PEO). Bioactivity assessment evidenced a shift in the surface phase of the Ti implant to generation of beta-tricalcium phosphate, a more bioresorbable material than HA. Metabolic activity assessments using human dental pulp stem cells revealed that Ti surfaces modified by the new nanocomposite are superior to bare and HA-modified Ti surfaces for cell attachment and proliferation<i>in vitro</i>. In addition, it successfully inhibited bacterial growth and induced osteogenesis on the implant surface. Finally, potentiodynamic polarization behavior of Ti implants before and after coating confirmed that a thick oxide interface layer on the modified Ti surface acts as an electrical barrier and protects the substrate layer from corrosion. Therefore, the HA/silica-EDTA/Ag nanocomposite presented here, compared to HA, can better coat Ti dental implants due to its good biocompatibility and osteoinductive activity, along with improved biological stability.