Antibacterial Efficacy and Antioxidant Potential of Hafnium-coated Titanium Implants: An In-vitro Assessment

Introduction: Implant related infections and oxidative stress remain major concerns in dental and orthopaedic implantology, often leading to complications and implant failure. Titanium, though biocompatible and widely used, lacks inherent antibacterial and antioxidant capabilities. To overcome these limitations, surface coatings on biomedical implants have gained significant attention for their ability to enhance antibacterial and antioxidant properties, addressing challenges such as infection and oxidative stress. Aim: This study evaluated the antibacterial efficacy and antioxidant potential of hafnium-coated titanium implants through in-vitro experiments. Materials and Methods: The present in-vitro study was conducted at the Saveetha Dental College and Hospitals, Chennai, India, over a duration of three months (March to May 2024) in an in-vitro experimental set-up. Hafnium oxide nanoparticle-coated titanium micro screws (Group A; n=6) were compared with uncoated titanium screws (Group B; n=6) using Zone of Inhibition (ZOI) and bacterial viability tests against S. mutans, E. faecalis, and C. albicans. Antioxidant activity was assessed using the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) radical scavenging assay. Statistical analysis was performed using IBM Statistical Package for Social Sciences (SPSS) Statistics for Windows, version 23.0 (IBM Corp., Armonk, N.Y., USA). Independent sample t-tests were used to compare the mean values of ZOI, Colony Forming Units (CFU) counts, and DPPH scavenging percentages between the two groups. Results: Hafnium-coated titanium implants exhibited significant antibacterial activity, with ZOI values of 13.0±0.5 mm, 24.0±0.6 mm, and 21.0±0.4 mm for S. mutans, E. faecalis, and C. albicans, respectively, outperforming uncoated titanium (11.0±0.4 mm, 22.0±0.5 mm, and 16.0±0.6 mm, respectively). Bacterial viability tests further confirmed the efficacy of hafnium coatings, showing reduced CFU counts (S. mutans: 3.0±0.2×104 CFU/ mL; E. faecalis: 2.5±0.3×104 CFU/mL; C. albicans: 4.0±0.2×104 CFU/mL) compared to uncoated controls. While the DPPH assay revealed moderate antioxidant activity for hafnium-coated surfaces, it was lower than uncoated titanium. Conclusion: These findings suggest that hafnium-coated titanium implants possess enhanced antibacterial properties, likely due to the inhibitory effects of hafnium ions on bacterial growth and biofilm formation. The moderate antioxidant activity indicates potential for reducing oxidative stress, improving implant biocompatibility. This study highlights the promise of hafnium coatings in developing infection-resistant and durable dental and orthopaedic implants. Further research is warranted to optimise coating performance and validate clinical applications.