Antimicrobial Behavior of Surface-Treated Commercially Pure Titanium (CpTi) for Dental Implants in Artificial Saliva—In Vitro Study

<b>Background/Objectives</b>:Titanium implant surface modifications enhance osseointegration and prevent microbial colonization, improving implant longevity. Antimicrobial coatings, particularly cerium- and bismuth-doped hydroxyapatite (CeHAp and BiHAp), have gained attention for reducing infection-related complications. This study evaluates the antimicrobial activity of CeHAp and BiHAp coatings on CpTi compared to untreated CpTi in artificial saliva at pH levels of 4.5, 6.5, and 8. <b>Methods</b>: Antibacterial efficacy against <i>Staphylococcus aureus</i> (<i>S. aureus</i>), <i>Escherichia coli</i> (<i>E. coli</i>), and <i>Candida albicans</i> (<i>C. albicans</i>) was assessed using the broth dilution method. Titanium rods coated with test compounds were incubated in inoculated nutrient broth, and microbial inhibition was determined via optical density at 600 nm. A statistical analysis was performed using the Kruskal-Wallis ANOVA test, the median and Interquartile Range were determined for the variables, and a Dwass-Steel-Critchlow-Fligner intergroup pairwise comparison was conducted. <b>Results</b>: The results showed that both the CeHAp and BiHAp coatings demonstrated significant antimicrobial activity against <i>S. aureus</i> (OD = 0.01) at pH 6.5, which was more pronounced than the activity observed against <i>E. coli</i> (OD = 0.05), with the difference being statistically significant (<i>p</i> = 0.001). The least antimicrobial activity was observed against <i>C. albicans</i> (0.21) at pH 8 (<i>p</i> = 0.001). <b>Conclusion</b>: These findings highlight the pH-dependent effectiveness of BiHAp and CeHAp coatings in inhibiting microbial growth. Their application on titanium implants may enhance antimicrobial properties, contributing to improved dental implant success and broader biomedical applications.