Macrophage Depletion Reduces Bone Loss and Alters Inflammatory Responses: A Mouse Peri-Implantitis Model

Aim: To evaluate the impact of macrophage depletion on bone loss and inflammatory responses in a mouse model of peri-implantitis, assessing macrophage depletion potential as a therapeutic strategy. Materials and Methods: Using 6-week-old male C57BL/6 mice, peri-implantitis was induced by placing a silk ligature around osteointegrated dental implants. Mice were divided into three groups: Healthy control (Healthy group); peri-implantitis with liposomal phosphate-buffered saline (PBS group); and peri-implantitis with liposomal clodronate for macrophage depletion (CLOD group). Two weeks after ligature placement, micro-CT, histological and real-time PCR analyses were performed to assess bone density, leukocyte infiltration and cytokine levels. Results: The CLOD group showed a significantly higher bone-to-implant contact (74%) and bone volume relative to total volume (79%) compared to the PBS group (53% and 54%, respectively) and Healthy group (64% and 66%, respectively). Histological analysis revealed significantly reduced leukocyte and macrophage counts in the CLOD group. Additionally, TNF-α and IL-10 levels were significantly decreased in the CLOD group compared with the PBS group. Conclusion: Macrophage depletion effectively reduces bone loss and inflammation in peri-implantitis. This study highlights targeting macrophages as a promising approach for managing peri-implantitis, although further research is needed to optimize therapeutic strategies.