TLR4 and Peri-Implantitis: Studies have identified key differentially expressed genes (e.g., TLR4, CXCL8, FLT3, and IL1B), immune cell infiltration profiles (e.g., CD4+ T cells and macrophages), and microbiome signatures (e.g., distinct Fusobacterium nucleatum clades) in peri-implantitis [8,9,10].