<p>Peri-implantitis, an inflammatory condition caused by bacterial infection around an implant, is currently the leading cause of implant failure. <i>Porphyromonas gingivalis</i> (<i>P. gingivalis</i>), an anaerobic bacterial pathogen associated with periodontitis, is known to play a key role in peri-implantitis. To address this issue, the present study examined the antibacterial properties of silver ion (Ag⁺)-coated titanium implants against <i>P. gingivalis</i> and their ability to prevent bone loss. Ag⁺-coated implants, i.e., Ti implants coated with Ag⁺ ions on a hydroxyapatite film chelated with inositol hexaphosphate, demonstrated significant antibacterial activity against <i>P. gingivalis</i> in the Ti wire configuration in inhibition zone assays (<i>n</i> = 4 per group). Furthermore, in a murine model of ligature-induced peri-implantitis, these implants significantly reduced alveolar bone resorption compared to uncoated titanium controls. This preclinical study suggests that applying an Ag⁺ coating to dental implants is an effective strategy for preventing <i>P. gingivalis</i>–induced peri-implantitis. In the control group, bone loss of 19–25% relative to baseline was observed at day 28, whereas the Ag⁺-coated group exhibited only 15–20% bone loss (<i>n</i> = 8 per group per time point). These findings suggest the potential of Ag⁺ coating as a preventive strategy against peri-implantitis-associated bone loss.</p>