Seven studies compared RANKL and OPG levels in PICF of individuals with mucositis and peri-implantitis [34, 36–38, 42, 44, 46] (Table 4; Table S14); from them, six studies [34, 38, 42, 44] found higher levels of RANKL in peri-implantitis individuals. This evidence concerns the gene TNFSF11 and Peri-Implantitis.