Antibacterial performance of biomimetic hydroxyapatite-functionalized titanium surfaces against Staphylococcus aureus...

Peri-implantitis, driven by bacterial biofilm formation on implant surfaces, remains a leading cause of dental implant failure. Surface modification strategies that combine antibacterial properties with biocompatibility are therefore of considerable clinical interest. This in vitro study aimed to evaluate the antibacterial performance of hydroxyapatite (HA)-coated titanium surfaces, produced by radiofrequency (RF) magnetron sputtering with hydrothermal post-treatment, against Staphylococcus aureus and Escherichia coli in single-species and dual-species biofilm models.

Commercially available grade 2 titanium discs were divided into HA-coated (Ti-HA) and uncoated (Ti) groups (n = 8 per group per condition). Biofilm formation was assessed after 24 h of incubation at 37 °C using colony-forming unit (CFU) counts on selective media and optical density (OD) measurements at 630 nm. Statistical analysis included two-way ANOVA on log-transformed CFU data, Mann- Whitney U tests for pairwise comparisons, and Kruskal-Wallis tests for within-surface species comparisons.

Ti-HA surfaces demonstrated substantial antibacterial efficacy across all conditions, with CFU reductions ranging from 97.9% to 99.7% against both S. aureus and E. coli in single and dual species biofilm models (all p < 0.001). Surface type was the dominant determinant of bacterial viability, accounting for 74.1% of total variance (η2 = 0.741). Biofilm optical density measurements corroborated these findings across all conditions. The antibacterial effect was species-dependent, with greater efficacy against Gram-positive S. aureus than Gram-negative E. coli, while the dual species environment did not significantly alter coating performance for either species.

These findings provide proof-of-concept evidence that sputtered HA-coated titanium surfaces offer potent antibacterial activity against single and polymicrobial biofilms. While supporting the potential of this dual-function strategy to combine antibacterial protection with osteoconductivity, clinical translation requires further validation under simulated oral conditions that includes salivary pellicle formation and physiological loading as well as comprehensive in vivo studies.